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Article

Assessing the Environmental Impacts of the Black Soldier Fly-Based Circular Economy and Decentralized System in Singapore: A Case Study

by
Remondah R. Ramzy
1,*,
Vartika Goenka
1,
Marco A. El-Dakar
2 and
Janice Ser Huay Lee
1,3,*
1
Asian School of the Environment, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
2
Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
3
Earth Observatory of Singapore, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
*
Authors to whom correspondence should be addressed.
Sustainability 2025, 17(13), 6115; https://doi.org/10.3390/su17136115
Submission received: 14 May 2025 / Revised: 28 June 2025 / Accepted: 29 June 2025 / Published: 3 July 2025
(This article belongs to the Special Issue Achieving Environmental Sustainability through Waste Management and Energy Conversion)
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Abstract

Food waste management is a major global issue, and alternative protein sources like insect farming offer a sustainable solution. This study investigated the environmental impacts of black soldier fly larvae (BSFL) production using a Life Cycle Assessment (LCA), evaluating its role in both protein production and food waste treatment. The assessment considered three functional units: FU1 (1 kg of dried larvae), FU2 (per kg of protein), and FU3 (treatment of 1 ton of food waste). The results indicate that larvae rearing is the largest contributor to emissions in FU1 (46% of 18.51 kg CO2 eq). In FU2, BSFL protein shows a higher climate impact (49.41 kg CO2 eq) than fishmeal or soybean meal but requires significantly less land. FU3 demonstrates that BSFL-based composting can achieve net negative emissions (~−24.8 kg CO2 eq), outperforming conventional waste treatment. An optimized scenario (Scenario A) shows marked improvements across all units compared to a Business-as-Usual case, including a 79% reduction in FU1 emissions and a 577% increase in FU3 carbon savings. These findings underline the environmental advantages of BSFL systems, especially in Singapore, and support their potential as sustainable alternatives for protein production and food waste management.

1. Introduction

Singapore is heavily reliant on imported food products, with over 90% of its food being imported from 170 countries [1]. Despite the diversified import sources, Singapore is susceptible to rising food insecurity from the disruption of food chain supplies during the COVID-19 pandemic and the inflation of food prices. Additionally, the consumption patterns and growing population in Singapore have led to a near constant and increasing amount of generated food waste. The total amount of food waste generated in 2023 was 755,000 tons, with a recycling rate of approximately 18% in 2022 and 2023 [2]. While there has been governmental support for increasing recycling efforts, it has proven to be insufficient in combating food waste [3].
Singapore’s food waste management is largely centralized, relying on incineration and landfilling since 1972 [4]. While widely adopted due to its efficiency and convenience, this system has limited sustainability. Past efforts, such as a centralized anaerobic digestion (AD) facility in Tuas (2008–2011), and recent NEA-led initiatives, like co-digestion and on-site treatment systems, aim to improve recovery and reduce the environmental impact [5]. However, decentralized methods like composting and vermicomposting remain limited, and most food waste still ends up in waste-to-energy plants, contributing to the strain on Semakau Landfill.
Hence, there is a need for innovative techniques for the effective processing of food waste. One such technique that has received attention is insect-based food waste treatment [6,7], such as using black soldier flies (BSFs) due to their low economic and environmental footprint [8].
Hermetia illucens, commonly known as BSF, has gained popularity due to its potential as a protein source, replacing traditional sources such as fishmeal and soybean meal [9,10] in the aquaculture and livestock sector. BSF larvae are rich in nutrients, require minimal land and water to cultivate, and can thrive on organic waste streams, making them an attractive alternative to traditional livestock and aquaculture feed [11,12].
The use of BSF larvae (BSFL) in fish feed has environmental benefits for the aquaculture industry. Being a major food-producing sector, this industry uses large quantities of fishmeal and fish oil, recognized for their beneficial and essential nutrients like proteins, amino acids, and fats [13]. However, anthropogenic activities, such as overfishing to meet the increasing demands of fishmeal [14], and shortages of fish oil have established a need for alternative protein sources such as BSFL as a partial or full replacement for fishmeal [15]. The environmental benefits of BSFL have been established using the Life Cycle Assessment (LCA) methodology. This approach has consistently shown that black soldier fly production generates significantly lower greenhouse gas emissions and requires less land and water compared to traditional livestock farming, making it a more sustainable option for animal feed production [16]. A literature search on Google Scholar shows that despite the abundance of studies considering the life cycle of BSFL production and use in aquaculture (228 studies), few studies are based in the tropics, with even fewer conducted in Southeast Asia (22 studies), leading to a misrepresentation of the potential for global BSFL production. For instance, a study in Indonesia assessed the global warming potential (GWP) of a BSF waste treatment facility and found that the direct CO2-equivalent emissions were 47 times lower than those from composting. The Life Cycle Assessment (LCA) indicated that composting had double the GWP of BSF treatment based on a functional unit of 1 ton of biowaste (wet weight) [17]. Additionally, research in West Java, Indonesia, evaluated the environmental impacts of BSF bioconversion for dried larvae production. The LCA revealed that the production of prepupae had the highest environmental impact, followed by dried BSF production, with significant contributions to global warming potential, acidification, and terrestrial eutrophication [18]. These studies collectively underscore the potential for BSF larvae rearing in tropical climates, providing a solid foundation for the relevance of our research in Southeast Asia.
Therefore, the aim of this study is to develop an LCA of the bioconversion of post-consumer food waste to BSFL in Singapore, from the raw materials of food waste to its use in the aquaculture industry. The LCA is considered an efficient method for investigating the environmental profile of insect-based products, as it provides a comprehensive analysis of a product’s environmental footprint across its entire life cycle [19]. The method allows for a multicriteria evaluation across various impact categories linked to a product’s life cycle, such as natural resources, emissions, and land usage, complying with the ISO 14040 and 14044 standards, while enabling these evaluations to be conducted at a system level [20].
This study was conducted in the BSF facility at “Sustainability @ Tampines” in Singapore, which is referred to herein as the Tampines facility, a community-based facility that aims to spread awareness of the advantages of recycling food waste. The facility offers a circular economy system with four stages: the residents provide their food waste, which is fed to BSF, leading to by-products such as BSFL and frass; the frass is packaged as fertilizer, while the BSFL are fed to the on-site tilapia pond [21]. While current research on the LCA of BSF suggests the need for implementing such studies at full-scale industrial facilities for accurate assessments of the environmental impacts [22], the Tampines BSF facility presents a unique scenario that incorporates a decentralized small-scale system integrated within a residential area. Including the residents in the process of food waste collection promotes the principles of a circular economy using BSF.
This LCA study evaluates whether the decentralized facility represents an optimal BSF system by (1) examining the environmental performance of the decentralized model implemented at the Tampines BSF facility; (2) comparing the environmental performance of the BSF-derived feed with traditional feed sources, such as fishmeal and soybeans; and (3) comparing the environmental performance of BSF treatment for food waste with traditional waste management methods. These results will determine whether decentralized BSF facilities can be effectively integrated into other parts of Singapore, contributing to a more sustainable and circular waste management system.

2. Materials and Methods

2.1. Site Description and BSF Facility

Singapore’s community-based circular ecosystem, Sustainability @ Tampines Park, is a closed-loop model for recycling food waste (Figure 1) located in the township of Tampines.
The ecosystem comprises a 327.46 square meter black soldier fly (BSF) facility and a 537.3 square meter tilapia fish farm. This pilot project uses BSF larvae to upcycle food waste from the residents (Figure 1) and soya pulp residue, where the larvae are then used to feed the tilapia fish. The BSF frass is utilized as fertilizer for the community farm’s vegetable production. As an incentive, the participants who contribute their food waste receive “Green currency” rewards for their contributions, redeemable for food and program purchases. Our study was conducted at the Tampines BSF facility covering a period of eight months.

2.2. Life Cycle Assessment

This study employed the standardized LCA methodology, adhering to the ISO 14040 [24] and ISO 14044 [25] conventions. The LCA approach comprised four key stages: goal and scope definition (Section 2.2.1), system boundary (Section 2.2.2), Life Cycle Inventory (LCI, Section 2.2.3), and Life Cycle Impact Assessment (LCIA, Section 2.2.4). By following this structured approach, the study ensured a comprehensive and transparent assessment of the environmental impacts, including, but not limited to, climate change, freshwater and marine eutrophication, water scarcity, human health damage, and ecosystem quality damage.

2.2.1. The Goal and Scope of the Study

The LCA employed a multi-faceted methodology to capture the diverse environmental impacts associated with insect production. It incorporated three distinct assessment perspectives, each based on a specific functional unit (FU):
FU1: Production of 1 kg (dry matter) of BSFL. This unit served as a reference point to enable a direct comparison with data from the scientific literature and other insect production systems.
FU2: Supply of 1 kg of protein incorporated into the aquaculture feed for the fish farm. This was used for evaluating the environmental impacts of BSF compared to soybean meals or fishmeal as protein sources in the feed of aquatic species (more details in the Supplementary Materials).
FU3: Processing 1 ton of food waste from Tampines. This FU compared the environmental impacts of the BSF treatment with alternative food waste treatments.
The BSF larvae were assumed to replace soybean meal or fishmeal where it was a credit in the FU3. The protein content of soybean meal is 53.9% DM [26], and the Ecoinvent process for fishmeal assumes 63–65% DM. These values were used to adjust the respective processes accordingly. Firstly, we calculated the amount of protein in the dry matter BSF larvae and then calculated the amount needed to replace the soybean meal (53.9% protein) and fishmeal (63–65% protein) by using the following equations:
T h e   a m o u n t   o f   p r o t e i n   ( k g )   =   T h e   a m o u n t   o f   d r y   m a t t e r   B S F   l a r v a e   ( k g ) T h e   a m o u n t   o f   d r y   m a t t e r   B S F   l a r v a e   t o   g i v e   1   k g   p r o t e i n   ( k g ) T h e   a m o u n t   o f   s o y b e a n   m e a l   n e e d e d   ( k g )   =   T h e   a m o u n t   o f   p r o t e i n   i n   B S F   l a r v a e   ( k g ) 0.539 T h e   a m o u n t   o f   f i s h m e a l   n e e d e d   ( k g )   =   T h e   a m o u n t   o f   p r o t e i n   i n   B S F   l a r v a e   ( k g ) 0.64

2.2.2. System Boundary

The system boundary for this LCA encompassed the full cradle-to-gate life cycle of BSF larvae production for aquaculture feed. The boundary included the following stages: (1) food waste sourcing and collection (FWC), (2) BSF larvae rearing (LR), (3) larval processing (LP), (4) product management and distribution of BSF larvae (PM), and (5) administrative support operations (ASOs) (Figure 2). Key metrics such as growth rates and diet composition were measured, along with the collection of the larvae and remaining frass.

2.2.3. Frass as a Co-Product and Application of the Avoided Burden Approach

Alongside the main product, the BSF rearing process also yields frass, a nutrient-rich by-product that can be used as an organic fertilizer or soil conditioner. When applied in agriculture, frass can replace conventional inputs such as synthetic nitrogen fertilizers.
To account for this in the LCA, the avoided burden (or system expansion) method was applied, following the approach described by [27]. The avoided product (AvPr) represents the conventional resource that is displaced through frass utilization. This substitution was applied across all functional units. In the case of FU1 and FU2, the frass was treated as a co-product, with system expansion used to reflect its environmental credit. For FU3, the frass was a primary output and credited accordingly to reflect its role in circular waste management.
According to [28], the final frass was assumed to contain 0.025 kg of nitrogen (N), 0.0202 kg of potassium (K), and 0.0057 kg of phosphorus (P) per 1 kg of dry matter. To account for the substitution of the traditional fertilizers by frass, these nutrient contents were converted into equivalent fertilizer product amounts based on the typical nutrient concentrations using the following equations, according to the amount of frass in each FU:
A m m o n i u m   n i t r a t e   e q u i v a l e n t   ( k g )   =   N i t r o g e n   i n   f r a s s   k g   ×   A m o u n t   o f   f r a s s   i n   e a c h   F U 0.34 T S P   e q u i v a l e n t   ( k g )   =   P h o s p h o r u s   i n   f r a s s   ( k g )   ×   A m o u n t   o f   f r a s s   i n   e a c h   F U 0.20 K C l   e q u i v a l e n t   ( k g )   =   P o t a s s i u m   i n   f r a s s   ( k g )   ×   A m o u n t   o f   f r a s s   i n   e a c h   F U 0.60

2.2.4. Life Cycle Inventory (LCI)

The Life Cycle Inventory phase involved the collection and quantification of all relevant inputs and outputs associated with the BSF larvae production system (Supplementary Materials). The system was evaluated based on three distinct functional units. For each functional unit, the material flows (e.g., food waste, water), energy consumption (e.g., electricity), and co-products (e.g., frass) were identified and quantified.
The foreground data collection for the LCA of the BSF larvae was conducted through weekly site visits to the Tampines facility, where the data were gathered through observations, measurements, and interviews with personnel. Detailed descriptions of the measurement procedures, instruments used, and data processing methods are provided in the Supplementary Materials (see Supplementary Materials, Section S1).

2.3. Life Cycle Impact Assessment (LCIA)

In this study, a prospective consequential LCA study was followed to assess the production of DBSFL to allow system expansion and the allocation of fertilizer credits via frass use. The study employed the SimaPro v9.6.0.1 software, developed by PRé Consultants. Data for the upstream production processes were obtained from the Ecoinvent 3.1 database (Ecoinvent, Zurich, Switzerland) [29]. IMPACT World+ was used for the calculation to quantify the environmental impacts; it considers midpoint categories and the impacts on ecosystem and human health as well as regional perspectives [30].

2.4. Scenario Analysis for Improvement

To evaluate the potential for environmental improvement, a scenario analysis was conducted using the three previously defined functional units as the Business-as-Usual (BAU) baseline.
In Scenario A (SA), three operational adjustments were implemented to improve the environmental performance of the BSF facility. First, the usage of the waste collection machine was reduced by 40%, limiting its operation to essential tasks only. Second, the air conditioning in the rearing room was restricted to 8 h per day, primarily during peak temperature periods, to reduce energy consumption while maintaining larval health. Third, the use of the freezer was discontinued entirely, thereby eliminating the energy demands associated with this appliance while still preserving the core functionality of the facility.

3. Results

Three areas are addressed in this section: (1) a comparison of insect production across the different processes; (2) a protein-level comparison between the insect larvae, soybean meal, and fishmeal; and (3) an assessment of the BSF-based composting relative to the traditional food waste treatment methods. The most significant impact categories and the associated production process are depicted in Figure 3. Additional data can be found in the Supplementary Materials.

3.1. Comparison of Insect Production Across Different Processes (FU1)

3.1.1. Environmental Impacts at the Midpoint Level for FU1

The environmental impacts of producing 1 kg of DBSFL from food waste are presented in Table S2, which summarizes the midpoint impact categories. Figure 3 presents the top impact categories and highlights which processes contributed the most to each category. Overall, the LR process indicated the greatest environmental impacts, while the PM process indicated the lowest impacts in most categories. The climate change impact of the DBSFL production was substantial, with 1.85 × 101 kg CO2 eq/FU1 generated at the midpoint indicator level. A closer examination reveals that the LR process was the primary contributor, responsible for 46% of the total CO2 emissions, followed by the FWC process (18%). Meanwhile, the other processes combined accounted for 36% of the emissions.
Digging deeper into the LR process, we found that the electricity consumption and the transportation of eggs were the key drivers behind its greenhouse gas emissions (Figure 3). Moreover, the highest amounts of “Fossil and nuclear energy use” and “Freshwater ecotoxicity” were recorded for the LR process (1.53 × 102 MJ deprived, 2.73 × 103 CTUe/FU1, Figure 3). Although the LR process was the dominant contributor to most of the midpoint impact categories, the ASO process had the highest contribution to “Water scarcity” (Figure 3).

3.1.2. Environmental Impacts at the Endpoint Level for FU1

The effects of BSF production from food waste on human health (HH) and ecosystem quality (EQ) are presented in Table S3, where producing 1 kg of DBSFL from food waste damaged 8.19 × 10−5 DALY /FU1 of human health.
The results show that the LR process contributed 48% for both HH and EQ. According to Table S3, the data reveal that “Climate change, long term” was the most significant contributor in all processes, followed by “Climate change, short term” (Figure S1).

3.2. Protein-Level Comparison Between BSF, Soybean Meal, and Fishmeal (1 Kg Protein, FU2)

3.2.1. Environmental Impacts at the Midpoint Level for FU2

The midpoint environmental impacts per 1 kg of protein show that the BSF protein generally had significantly higher environmental burdens than fishmeal and soybean across most categories (Table S4). BSF stands out with particularly high values in climate change (4.94 × 101 kg CO2-eq short term/FU2), fossil and nuclear energy use (8.64 × 102 MJ deprived/FU2), and freshwater ecotoxicity (1.6 × 104 CTUe/FU2). By contrast, fishmeal and soybean consistently showed lower impacts, with some categories even showing negative values, suggesting potential environmental credits, such as ozone depletion and particulate matter for fishmeal. While BSF performed better in land transformation (2.13 × 10−3 m2·yr arable) and freshwater eutrophication (negative value), it had higher burdens in nearly all toxicity- and energy-related categories.

3.2.2. Environmental Impacts at the Endpoint Level for FU2

The endpoint analysis revealed that BSF protein production had significantly higher impacts on both human health and ecosystem quality compared to fishmeal and soybean protein (Table S5). The total damage to human health from the BSF protein was 2.18 × 10−4 DALY/FU2, substantially greater than that from soybean (1.63 × 10−5 DALY) and fishmeal, which showed a net negative value (−1.35 × 10−5 DALY), indicating a possible offset or environmental credit. The BSF impacts were especially high in the categories related to climate change, particulate matter, and human toxicity. In terms of ecosystem quality, BSF again showed the highest burden, with a score of 5.88 × 101 PDF·m2·yr, followed by soybean (2.12 × 101) and fishmeal (2.13). The major contributors to the ecosystem impact of BSF included climate change, marine acidification, and freshwater ecotoxicity, with long-term climate change alone accounting for 3.03 × 101 PDF·m2·yr. Although the BSF protein showed slightly lower impacts in land transformation and eutrophication categories compared to soybean, its overall environmental footprint at the endpoint level remained significantly higher across most metrics.

3.3. Assessment of BSF-Based Composting Relative to Traditional Food Waste Treatments

3.3.1. Environmental Impacts at the Midpoint Level for FU3

Table S6 presents the midpoint impact categories associated with the treatment of 1 ton of food waste through BSF processing, composting, and open dumping. BSF treatment demonstrated clear environmental advantages in several key categories, including climate change impacts (both short and long term), where it resulted in net negative emissions of approximately −24.8 kg CO2 eq, compared to the significant emissions from composting and especially open dumping (up to 665 kg CO2 eq). Additionally, BSF showed reduced impacts or net benefits in areas such as mineral resource use, photochemical oxidant formation, and freshwater and terrestrial acidification. By contrast, open dumping consistently showed the highest environmental burden across most categories, particularly in freshwater ecotoxicity (4.82 × 105 CTUe) and climate change. Composting generally lay between BSF and open dumping in terms of environmental performance but still incurred positive impacts in nearly all categories.

3.3.2. Environmental Impacts at the Endpoint Level for FU3

The data in Table S7 compare the endpoint environmental impact scores of three treatment methods—BSF processing, composting, and open dumping—for 1 ton of food waste across both human health and ecosystem quality. The BSF treatment consistently showed lower or even beneficial impacts in multiple categories. For instance, it led to a net reduction in climate-change-related short-term health impacts (−2.04 × 10−5 DALY) and human toxicity cancer (short-term: −4.81 × 10−6 DALY), indicating potential health co-benefits. By contrast, open dumping resulted in the highest damage across nearly all human health categories, particularly in climate change (5.43 × 10−4 DALY) and total human health burden (5.97 × 10−4 DALY).
In terms of ecosystem quality, BSF again demonstrated favorable outcomes, with significant reductions in categories such as land transformation (−4.37 × 10−1 PDF·m2·yr) and terrestrial acidification (−3.23 PDF·m2·yr). Open dumping, however, exhibited the most severe ecosystem degradation, especially in freshwater ecotoxicity (2.79 × 102 PDF·m2·yr) and total ecosystem quality impact (4.28 × 102 PDF·m2·yr). Composting, while less harmful than dumping, still contributed substantially to several impact categories.
On the other hand, the single scorer results (expressed in EUR2003) for the treatment of 1 ton of food waste (FU3), presented in Figure S2, showed a stark contrast in environmental costs across BSF, composting, and open dumping. Overall, the BSF treatment exhibited the lowest environmental cost, with negative or near-zero values in several categories, indicating potential environmental benefits or minimal harm.

3.4. Scenarios Analysis

A comparative analysis between the BAU and SA reveals a substantial reduction in climate change (short-term) impacts across all three functional units. For FU1, representing the production of 1 kg of dried BSF larvae, the emissions decreased by 79%, dropping from 18.51 to 3.96 kg CO2 eq. FU2, which considered impacts per kilogram of protein, experienced a 63% reduction, falling from 49.41 to 18.14 kg CO2 eq. Most notably, FU3, which assessed the treatment of 1 ton of food waste, showed a dramatic shift from −24.80 to −167.95 kg CO2 eq, representing a 577% increase in net carbon savings (Figure 4).

4. Discussion

Despite the growing interest in BSFL production, there is a scarcity of environmental impact analyses focusing on the utilization of food waste as a substrate in this process [31], especially in Southeast Asia. The tropical climate of Southeast Asia offers unique challenges and opportunities for such production systems, making the findings of this study highly relevant to countries with similar environmental conditions. Furthermore, this study focuses on a community-oriented facility. By prioritizing community well-being, the facility contributes not only to sustainable agricultural practices but also to the creation of meaningful employment and the empowerment of local populations.

4.1. Comparison Across Insect Production Process

According to multiple sources [32,33,34,35], utilizing low-value food side streams or manure can have sustainable benefits. Many studies have shown that food systems have a large environmental impact that is linked to their carbon footprint and CO2 emissions [36,37,38].
The environmental impacts of producing 1 kg of dried BSF larvae were influenced significantly by the LR process, which contributed the largest share of impacts across several categories, particularly in climate change and energy use. This finding is consistent with other studies in the field of insect farming, such as [39,40], which highlight the energy intensity of insect farming as a major determinant of environmental burden. Numerous studies have consistently shown that the rearing stage is the primary contributor to midpoint impact categories throughout the life cycle of BSF and other insect production. For instance, ref. [41] investigated the LCA for mealworm production, ref. [42] studied the LCA of BSF production, and [22] mentioned that larvae rearing was the most energy-intensive stage, using twice as much energy as processing. The energy required for maintaining the optimal conditions for larvae rearing was a key factor driving the high CO2 emissions observed in this study. Specifically, electricity consumption and the transportation of eggs were identified as the primary contributors to greenhouse gas emissions. This agrees with [43], who mentioned that energy use is a critical component in insect rearing. Studies in the European context highlight the crucial role of electricity consumption and energy source selection in determining the environmental impacts of insect meal production [22,41]. The rearing of larvae and processing of raw materials are particularly energy-intensive steps, and the choice of energy sources has a profound effect on the sector’s environmental performance and significantly contributes to GWP [43].
The FWC process also plays a role in contributing to CO2 emissions (18%), though to a lesser extent compared to larvae rearing. This suggests that, while the food waste collection process has a smaller direct impact, its influence on the overall environmental footprint of BSF production should not be overlooked. Previous research, such as that by [44], also shows that the feedstock collection and preprocessing stages can contribute to the overall environmental impact, depending on the waste sourcing methods and transportation efficiency.
The current study reports a significantly higher energy usage of 324 MJ/kg of dried BSF larvae compared to [42] in South Africa, who reported 85 MJ/kg. This substantial increase in energy consumption can be attributed to the broader system boundaries and smaller production scale in our case study. However, the improved scenario in our analysis (94 MJ/kg) is notably lower than several previously reported values. For example, ref. [32] estimated 148.4 MJ/kg in West Africa, and [39] reported 99.6 MJ/kg for insect protein meal production in Germany. On the other hand, our results are higher than those of [45] (26 MJ/kg) and [45] (15.1 MJ/kg) for 1 kg of insect protein. Similarly, ref. [41] found that producing 1 kg of fresh mealworm larvae required 24.29 MJ, while producing 1 kg of larvae meal required 141.29 MJ. The authors of [40] reported 33.68 MJ/kg for fresh mealworm larvae, and ref. [43] estimated an exceptionally high 9329 MJ/ton for dried housefly larvae meal.
At the endpoint level, the environmental impacts of BSF production on HH and EQ are notably high, especially in terms of long-term climate change impacts. The LR process remains the primary contributor to these damages, aligning with the observed CO2 emissions in the midpoint-level analysis. These findings echo those of [46], who found that insect farming, while generally more sustainable than traditional livestock farming, still poses significant risks to both human health and ecosystem quality due to the energy requirements of the production system. The long-term climate change impact is particularly significant, likely due to the emission of greenhouse gases during the rearing phase, where both electricity use and transportation are critical.
Additionally, the fossil and nuclear energy use and freshwater ecotoxicity associated with the LR process are significant contributors to the environmental burdens. These findings highlight the need for targeted interventions aimed at improving the energy efficiency of BSF production and minimizing the use of fossil fuels in energy generation. The authors of [47] also pointed out that reducing the reliance on non-renewable energy sources would be a key strategy for improving the environmental profile of insect farming.

4.2. Protein-Level Comparison Between Insect Larvae, Soybean Meal, and Fishmeal

Studies such as [48] demonstrate that dried maggot larvae have comparable effects to commercial feed on the growth and nutrient quality of Nile tilapia. Moreover, according to [49], the fish readily accepted experimental diets containing 100% BSF meal replacement. While BSF protein production may exhibit higher environmental impacts in categories such as energy use and greenhouse gas emissions, it also offers notable nutritional benefits. BSF meal typically contains 35–45% crude protein and has a favorable amino acid profile, including essential amino acids like lysine and methionine [10]. Furthermore, the fatty acid composition can be varied in BSFL with different organic waste usages [50]. By comparison, fishmeal offers a slightly higher protein content but is associated with overfishing and marine ecosystem degradation, while soybean meals, though lower in environmental impact, often lack certain essential amino acids and are linked to deforestation. However, the environmental impacts of producing BSF protein are notably higher than those of both fishmeal and soybean meals across a wide range of impact categories, particularly in areas related to climate change, fossil and nuclear energy use, and freshwater ecotoxicity. These results align with previous studies, such as those by [51,52], who reported that although insect larvae have a relatively low land-use impact, the energy consumption associated with their production remains a significant environmental challenge. The high energy demands of the larvae rearing process (which contributes heavily to BSF’s environmental burden) suggest that the energy intensity of the farming process is a critical factor influencing the overall environmental performance of insect-based proteins.
Our results (49.4 kg CO2 eq per 1 kg of insect protein) showed higher emissions than the production of 1 kg of insect protein in Germany, which was 15.1 kg CO2 eq [39]. Additionally, the emissions were also higher than those reported in a study from South Africa, which recorded 6 kg CO2 eq per 1 kg of insect meal [42]. The higher emissions observed in our study compared to those studies may be attributed to the smaller scale and lower efficiency of the decentralized BSF facility assessed. Unlike large-scale commercial operations, which benefit from economies of scale, streamlined logistics, and optimized energy use, smaller facilities often face higher per-unit emissions due to less efficient energy consumption, transportation constraints, and limited process integration.
By comparison, fishmeal and soybean meals consistently show lower environmental impacts across most categories. The negative values in certain categories for fishmeal, such as ozone depletion and particulate matter, suggest that fishmeal production may provide potential environmental credits, likely due to the high nutrient density of fishmeal and, possibly, the recycling of by-products from the fishing industry. This aligns with the findings from studies like [43], who noted that fishmeal, while not without its own environmental impacts, generally has a more favorable profile compared to insect-based proteins in categories such as land use and toxicity. Moreover, our results align with those of [45], who found that BSF-larvae-fed food and feed products have higher environmental impacts than traditional protein sources. The authors of [53] noted that multiple studies have found that insect-based feeds and pet foods may, in some cases, result in greater environmental impacts compared to the conventional alternatives. According to [54], producing insect protein could result in significantly higher climate impacts, potentially up to 13.5 times greater than soybean protein and 4.2 times higher than fishmeal.
However, BSF protein does show some advantages, particularly in land transformation and freshwater eutrophication. While these categories remain less impactful for BSF compared to fishmeal, they demonstrate that insect farming has a more efficient use of land and potentially fewer impacts on freshwater resources than some traditional animal feed sources. The negative freshwater eutrophication value observed for BSF might suggest that certain aspects of the insect production process, such as organic waste utilization as feed, could provide some mitigation of the environmental impact, as seen in studies that advocate the use of food waste as a key feedstock for insect larvae [28]. Based on [55], the BSF system’s environmental impacts, including GWP and EU effects, surpass those of soybean meals, with the majority of the carbon footprint derived from transporting food waste and from the drying process. Our results from the Singapore case study show that BSFL protein production outweighs the emissions from soybean meal due to the energy-intensive BSF rearing process with a low production of BSFL, not from the transportation of food waste as demonstrated by [22].

4.3. Assessment of BSF-Based Composting Relative to Traditional Food Waste Treatment Methods

BSFL treatment offers key advantages over traditional methods like landfilling, incineration, anaerobic digestion (AD), and composting. Landfilling and incineration have high emissions and low resource recovery. AD and composting recover nutrients but are slower and produce lower-value outputs. By contrast, BSFL can quickly convert food waste into valuable protein and organic fertilizer [50]. It also works well in both centralized and decentralized systems. While the energy use can be high, BSFL provides an efficient and sustainable solution aligned with circular economy goals.
The comparison of BSF-based composting to traditional food waste treatment methods, such as composting and open dumping, reveals that BSF processing presents significant environmental advantages across several impact categories. As observed in our analysis, BSF treatment demonstrates net negative emissions in climate change impacts, both in the short term and long term, with an estimated reduction of approximately −24.8 kg CO2 eq. This is in stark contrast to composting, which has positive emissions, and open dumping, which shows substantial emissions (up to 665 kg CO2 eq). These findings align with those of [56], who highlighted that insect-based waste treatment technologies, like BSF, have the potential to reduce greenhouse gas emissions compared to traditional waste management practices. BSF stands out in its ability to convert organic waste into a valuable resource (protein) while simultaneously mitigating emissions, thus offering both environmental and economic benefits [57].
When comparing BSF to open dumping, the differences in the environmental impacts become even more pronounced. Open dumping consistently shows the highest environmental burden, especially in categories like freshwater ecotoxicity and climate change. This is consistent with findings from [58], which report that open dumping is one of the most harmful waste management practices, with severe impacts on both human health and ecosystem quality. The BSF system, on the other hand, not only mitigates the harmful effects of food waste but also avoids the severe contamination risks associated with open dumping, which further supports the conclusion that BSF offers a more sustainable alternative to waste disposal.
These findings are consistent with those of [59], who examined the environmental and economic aspects of various food waste treatment methods in Singapore. Yin’s study found that BSF treatment outperforms other options, including incineration, anaerobic digestion (with incineration or composting as digestate treatment), and Biomax Rapid Thermophilic Digestion, in key impact categories such as acidification potential, global warming potential, eutrophication potential, and human toxicity.

4.4. Scenarios for Improvement

In Scenario A, three operational adjustments were implemented to demonstrate how targeted interventions could improve the environmental performance of the BSF facility. These changes were selected based on practical feasibility and observations from the case study site. First, the operation of the waste collection machine was reduced by 40%, limiting its use to essential tasks and thereby lowering the fuel consumption. Second, the air conditioning in the rearing room was restricted to 8 h per day during peak temperature periods to reduce the electricity use while maintaining suitable conditions for larval development. Third, the use of the freezer was discontinued entirely, eliminating a major source of energy demand without compromising the core functions of the facility. These modifications addressed the most energy-intensive components of the system and reflect realistic improvements that could be adopted in similar decentralized BSF operations.
The findings indicate a clear environmental benefit of transitioning from the BAU to SA, particularly in the context of integrated food waste management and insect-based protein production. These improvements reflect not only changes in emission profiles but also a shift toward more circular and resource-efficient systems.
The use of food waste as a primary feedstock in SA plays a crucial role in reducing the environmental impacts. This aligns with prior studies that emphasize the carbon mitigation potential of diverting organic waste from landfills to valorization pathways. For instance, ref. [60] demonstrated that the bioconversion of food waste via BSF larvae significantly reduced the methane emissions compared to anaerobic digestion or composting.
Additionally, the increased environmental efficiency per unit of protein supports the broader argument that insect farming can complement or replace conventional animal agriculture in certain applications. Several LCA studies, including [53], report that insect-derived protein typically incurs lower GHG emissions and land-use demands compared to beef, pork, or even poultry, particularly when reared on low-value waste streams.
What sets Scenario A apart is not just the reduction in absolute emissions but the capacity to deliver net negative climate impacts in some cases. This reinforces the concept of BSF-based systems as not only low-impact but potentially climate-positive, especially when the system boundaries account for the avoided impacts from waste management. Similar conclusions were drawn by [59,61], who found that BSF systems could act as carbon sinks when integrated with composting or biochar production.
While these results are promising, they are sensitive to contextual variables such as local electricity grids and larval processing methods. Comparative studies across regions, like those by [62], highlight how differences in the energy mix and waste composition can significantly alter the environmental profile of BSF systems. Therefore, the broader adoption of this model should consider regional optimization and policy support to maximize the sustainability gains.

4.5. Establishing Decentralized BSFL Facilities

Implementing decentralized BSF facilities in urban areas presents both challenges and opportunities. Key challenges include the limited space availability, odor and pest control, the regulatory hurdles, and the need for consistent food waste quality. Energy demand and public acceptance can also pose barriers, especially in densely populated areas. However, there are notable opportunities. Decentralized BSF systems can reduce transportation emissions, lower food waste at the source, and enhance local food security by producing protein and fertilizer close to where they are needed.
Having decentralized BSFL facilities that are in close proximity to food waste sources, such as the one from our case study in Singapore, and that use a waste collection machine eliminates the need for food waste transportation. This reduces emissions from the transport process of waste collection, thereby minimizing the environmental impact of the diet provision for DBSFL production. The feed production process, particularly the procurement of raw materials, is shown to be the main contributor to the environmental impacts in the baseline insect production scenario [39]. Our results concur with those of [63], who identified diet provision, particularly insect feed, as the primary driver of the environmental impacts in non-manure diets, with the notable exceptions of fossil resource use potential and particulate matter formation potential.
Singapore’s initiatives to integrate decentralized BSF larvae facilities harness food waste as a nutrient-rich feedstock, converting it into valuable resources. Strategically locating these facilities in industrial estates (Jurong, Changi) [64], waste management hubs (Tuas, Senoko) [65], agricultural areas (Kranji, Lim Chu Kang) [66], and urban farms has enhanced Singapore’s waste management ecosystem. Moreover, this community-based waste collection initiative also served an educational purpose by raising awareness about sustainable waste management. It encouraged public participation, promoted a culture of environmental responsibility, and inspired Singaporeans to adopt eco-friendly practices and contribute to a cleaner, greener future. With supportive policies and proper planning, decentralized BSF facilities can become a viable and sustainable component of urban waste management strategies.
While this study focuses on environmental impacts, the economic feasibility of BSF-based systems is a crucial factor for large-scale adoption. Previous studies have shown that the production costs are influenced by factors such as the facility scale, energy use, labor, and feedstock availability [67,68,69,70,71]. The revenue potential comes from both larvae (as feed or food) and frass (as fertilizer), making BSF systems attractive in circular economy models. However, the upfront capital investment and operational costs remain challenges, particularly for decentralized facilities. Future work should incorporate a techno-economic assessment to complement the environmental analysis and guide implementation strategies.

4.6. Study Limitations

This study has several limitations that should be considered. Firstly, the environmental impact data for fishmeal, soybean meal, and conventional food waste treatment methods were obtained from the Ecoinvent v3.8 database due to the lack of site-specific data. While Ecoinvent provides reliable and widely accepted datasets, these may not accurately reflect the current technologies or regional conditions in Singapore, which could have affected the precision of the comparative assessments. Secondly, the BSF production system was modeled using a combination of primary data and literature sources, which may have introduced variability in the data quality and system boundaries across scenarios.
The assumptions regarding consistent food waste composition and stable BSF rearing conditions may not have captured the operational variability in real-world systems. Additionally, the analysis focused solely on the environmental impacts, excluding the social and economic considerations that are crucial for holistic sustainability assessments. The functional units used did not account for differences in protein quality or bioavailability, which may influence the true comparability of BSF larvae with conventional protein sources. Lastly, the long-term environmental benefits such as soil health improvements from BSF compost application were not fully quantified. Future studies should aim to integrate comprehensive primary data, explore regional variability, and expand the scope to include dynamic modeling and multi-dimensional sustainability metrics.

5. Conclusions

This study conducted a Life Cycle Assessment (LCA) of black soldier fly (BSF)-based systems in Singapore, focusing on three key applications: insect protein production, protein source comparison, and organic waste management. The findings show that larvae rearing is the most environmentally impactful stage, primarily due to the electricity consumption for climate control and drying processes.
When comparing BSF-derived protein with conventional protein sources, BSF protein demonstrated higher environmental impacts in terms of climate change potential and cumulative energy demand. However, it outperformed fishmeal and soybean meal in land-use efficiency and eutrophication potential. A scenario analysis further revealed that energy-efficient configurations, such as Scenario A, significantly reduce the environmental burdens, suggesting that BSF protein production can be environmentally viable if energy use is minimized.
BSF technology presents a promising waste management solution, especially for decentralized urban systems. However, its environmental viability as a protein source depends heavily on energy optimization. These findings suggest key actions for policymakers and practitioners, including supporting decentralized BSF facilities through regulations, incentives, and streamlined licensing. Integrating BSF into urban waste management, investing in energy-efficient infrastructure, and promoting community education can improve the sustainability and operational performance. Future development should focus on enhancing energy efficiency, scaling integrated systems, and maximizing resource recovery to fully realize the sustainability potential of BSF-based circular economy models.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/su17136115/s1. Figure S1: Single Score Environmental Impacts on Human Health and Ecosystem Quality per 1 kg of BSF Dry Matter Produced, by IMPACT World Endpoints; Table S1: Energy and Material Flow; Table S2: Process-specific midpoint environmental impacts to produce 1 kg of BSF larvae (dry matter). Impact intensity is color-coded by row, from dark green to red to indicate the lower/higher indicators where dark green is the lowest and red is the highest; Table S3: The endpoint environmental impact scores for each process contributing to the production of 1 kg of BSF larvae on a dry matter basis; Table S4: Midpoint Environmental Impacts per 1 kg of Protein: BSF vs. fishmeal and soybean. Impact intensity is color-coded by row from dark green to red to indicate the lower/higher indicators where dark green is the lowest and red is the highest; Table S5: Endpoint Environmental Impact Scores per 1 kg of Protein: BSF, fishmeal, and soybean; Table S6: Midpoint impact categories for different treatments of one tonne of food waste. Impact intensity is color-coded by row from dark green to red to indicate the lower/higher indicators where dark green is the lowest and red is the highest; Table S7: Endpoint environmental impact scores for different treatments of one tonne of food waste; Figure S2: Single Score Environmental Impacts on Human Health and Ecosystem Quality per 1 ton food waste treatments, by IMPACT World Endpoints. References [72,73] are cited in the supplementary materials.

Author Contributions

Conceptualization, R.R.R., M.A.E.-D. and J.S.H.L.; methodology, R.R.R. and J.S.H.L.; software, R.R.R.; validation, R.R.R.; formal analysis, R.R.R. and M.A.E.-D.; investigation, M.A.E.-D.; data curation, R.R.R.; writing—original draft preparation, R.R.R., M.A.E.-D. and V.G.; writing—review and editing, R.R.R., V.G. and J.S.H.L.; visualization, R.R.R.; supervision, J.S.H.L.; project administration, J.S.H.L.; funding acquisition, J.S.H.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was jointly funded by the National Research Foundation of Singapore (NRF2020-THE003-0003/A00085140000) and the Ministry of Education Singapore (A00044240000).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding authors.

Acknowledgments

The authors thank Jonathan Poh and Wei Zhe Teo from Otolith Enrichment for providing data on sustainability-Tampines park’s project.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
BSFBlack soldier fly
BSFLBlack soldier fly larvae
LCALife Cycle Assessment
LCILife Cycle Inventory
LCIALife Cycle Impact Assessment
FUFunctional unit
FWCFood waste source and collection
LRLarvae rearing
LPLarval processing
PMProduct management and distribution of BSF larvae
ASOAdministrative support operations
AvPrAvoided product
BAUBusiness-as-Usual
SAScenario A
DBSFLDried black soldier fly larvae
HHHuman health
EQEcosystem quality
DALYDisability-adjusted life year
PDF·m2·yrPotentially disappeared fraction per square meter per year
GWPGlobal warming potential
EUEuropean Union

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Figure 1. (a) Site map for BSF at Tampines, modified from en.wikipedia [23]; (b) BSF rearing facility overview, (c) larval rearing tray, (d) food waste collection machine, and (e) aquaculture farm adjacent to the BSF facility (Source: R. Ramzy).
Figure 1. (a) Site map for BSF at Tampines, modified from en.wikipedia [23]; (b) BSF rearing facility overview, (c) larval rearing tray, (d) food waste collection machine, and (e) aquaculture farm adjacent to the BSF facility (Source: R. Ramzy).
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Figure 2. The system boundary (--) for the Life Cycle Assessment of BSF larvae production. Activities in the foreground system are shown in black and background activities are shown in gray, with credits for avoidance and arrows representing exchanges.
Figure 2. The system boundary (--) for the Life Cycle Assessment of BSF larvae production. Activities in the foreground system are shown in black and background activities are shown in gray, with credits for avoidance and arrows representing exchanges.
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Figure 3. An environmental impact breakdown by process for producing 1 kg of BSF dry matter. The y-axis represents the different processes, where FWC indicates food waste sourcing, LR indicates larvae rearing, LP indicates larval processing, PM indicates product management, and ASO indicates administrative support operations.
Figure 3. An environmental impact breakdown by process for producing 1 kg of BSF dry matter. The y-axis represents the different processes, where FWC indicates food waste sourcing, LR indicates larvae rearing, LP indicates larval processing, PM indicates product management, and ASO indicates administrative support operations.
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Figure 4. Comparison of climate change (short-term) impacts between Business-as-Usual (BAU) and Scenario A (SA) across three functional units.
Figure 4. Comparison of climate change (short-term) impacts between Business-as-Usual (BAU) and Scenario A (SA) across three functional units.
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MDPI and ACS Style

Ramzy, R.R.; Goenka, V.; El-Dakar, M.A.; Lee, J.S.H. Assessing the Environmental Impacts of the Black Soldier Fly-Based Circular Economy and Decentralized System in Singapore: A Case Study. Sustainability 2025, 17, 6115. https://doi.org/10.3390/su17136115

AMA Style

Ramzy RR, Goenka V, El-Dakar MA, Lee JSH. Assessing the Environmental Impacts of the Black Soldier Fly-Based Circular Economy and Decentralized System in Singapore: A Case Study. Sustainability. 2025; 17(13):6115. https://doi.org/10.3390/su17136115

Chicago/Turabian Style

Ramzy, Remondah R., Vartika Goenka, Marco A. El-Dakar, and Janice Ser Huay Lee. 2025. "Assessing the Environmental Impacts of the Black Soldier Fly-Based Circular Economy and Decentralized System in Singapore: A Case Study" Sustainability 17, no. 13: 6115. https://doi.org/10.3390/su17136115

APA Style

Ramzy, R. R., Goenka, V., El-Dakar, M. A., & Lee, J. S. H. (2025). Assessing the Environmental Impacts of the Black Soldier Fly-Based Circular Economy and Decentralized System in Singapore: A Case Study. Sustainability, 17(13), 6115. https://doi.org/10.3390/su17136115

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