Search Results (5)

Producing Class A biosolids is a beneficial way to reuse wastewater treatment solids, but most conventional processes are energy-intensive and expensive. There is growing interest in the use of low-cost, low-tech (LCLT) Class A biosolids treatment processes, especially at small water resource recovery facilities (WRRFs). This study used a holistic sustainability assessment to examine the environmental, economic, and social sustainability of conventional and LCLT processes at small WRRFs. The technologies studied were Direct Heat Drying, Composting, Lagoon Storage, Air Drying, and Temperature-Phased Anaerobic Digestion (TPAD). Environmental impacts were determined by conducting life-cycle assessments for all technologies, which is described in detail in prior published work. Economic impacts were quantified with a life-cycle cost assessment approach over a 25-year time horizon. Potential social impacts of each process were assessed by investigating case studies and surveys of social response to biosolids and estimating a relative impact score in a number of categories reported to be important to stakeholders in this technical domain. Impacts were normalized and compared to assess the best processes under a range of weighting scenarios. TPAD and Air Drying were the most sustainable processes when all domains were weighted equally. TPAD was projected to have low environmental and social impacts, which made up for its relatively high lifetime cost. Air Drying was the least expensive process in our analysis and had a modest environmental footprint, but there is potential for higher social impacts if the process is not sited and maintained properly. Because different communities are likely to prioritize or weight environmental, economic, and social impacts differently, a three-component mixing diagram was used to illustrate that Air Drying (economic), TPAD (environmental), or Direct Heat Drying (social) could become the preferred biosolids treatment process depending on which of the three sustainability domains was prioritized in the analysis. Full article

The sustainable management of organic waste is a global priority due to its environmental impact and the increasing pressure on urban and rural systems, particularly in regions with limited technological infrastructure. This study introduces and validates a comprehensive methodology based on Digital Twins (DTs) to optimize production and service systems in organic waste management. The methodology includes contextual and propositional phases and is built on a modular three-layer architecture (physical, cloud, and virtual) that enables real-time monitoring, simulation, and feedback. It was validated through a field implementation in a composting facility in Cajamarca, Colombia. The results showed a 10% increase in composting efficiency and a monthly gain of 1200 kg of compost. A statistical analysis confirmed a significant increase in process efficiency (p < 0.001) and a reduction in performance variability (p < 0.01). The return on investment reached 18,957.6% using low-cost technology. These findings demonstrate the viability and adaptability of the proposed methodology for low-tech environments and support its potential for scaling in circular economy applications across waste management and agriculture. Full article

Producing Class A biosolids that can be distributed or land-applied without restriction is a beneficial way to reuse wastewater treatment solids. For small water resource recovery facilities (WRRFs) in particular, low-cost, low-tech (LCLT) processes may be an appealing alternative to conventional technologies for producing Class A biosolids, such as processes to further reduce pathogens (PFRPs). Conventional Class A biosolids treatment processes tend to be energy-intensive and involve complex equipment and operations. However, a systematic comparison of the overall sustainability of conventional processes and LCLT alternatives for producing Class A biosolids to aid decision makers in selecting treatment processes is not readily available. Therefore, this study used life cycle assessments to compare five Class A biosolids treatment processes, including three conventional processes—Composting, Direct Heat Drying, and temperature-phased anaerobic digestion (TPAD)—and two LCLT processes—Air Drying, and long-term Lagoon Storage followed by Air Drying—on the basis of their environmental impacts. The environmental impacts were normalized to facilitate a comparison of the processes. The results indicate that Composting and Direct Heat Drying had the most significant environmental impacts, primarily from the biogenic emissions during Composting and the natural gas requirements for Direct Heat Drying. In comparison, TPAD and Air Drying had the lowest environmental impacts, and Lagoon Storage had intermediate impacts. Thus, LCLT processes may be more sustainable than some, but not all, conventional PFRPs. Full article

Urban agriculture is sprouting throughout the world nowadays. New forms of urban agriculture are observed such as rooftop farming. In the case of low-tech rooftop farming projects, based on recycled urban waste, one of the key issues is the type of substrate used, as it determines the functions and ecosystem services delivered by the green roof. Using a five year experimental trial, we quantified the food production potential of Technosols created only with urban wastes (green waste compost, crushed wood, spent mushroom), as well as the soil fertility and the potential contamination of food products. Regarding food production, our cropping system showed promising results across the five years, in relation with the high fertility of the Technosols. This fertility was maintained, as well as the nutrients stocks after five cropping years. Most of the edible crops had trace metals contents below existing norms for toxic trace metals with nevertheless a concern regarding certain some trace metals such as Zn and Cu. There was no trace metal accumulation in the Technosols over time except for Zn. This study confirmed that constructing Technosols only from urban wastes is a suitable and efficient solution to design rooftops for edible production. Full article

This paper presents a three-year pilot experience of a new municipal waste management system developed in Navarre, Spain that integrates composting and hens. The aim of this new system is to motivate the general public to participate more in waste prevention programs. The Composter-Henhouse (CH) is a compact facility comprised of a henhouse and three composters. This is shared by 30 families who provide the organic part of their kitchen waste to feed the hens. Hens help speed up the composting process by depositing their droppings and turning the organic residue into compost. This study assesses the CH in terms of treatment capacity, the technical adequacy of the composting process, the quality and safety of the compost obtained and some social aspects. Over three years, the CH has managed nearly 16.5 tons of organic waste and produced approximately 5600 kg of compost and more than 6000 high-quality fresh eggs. No problems or nuisances have been reported and the level of animal welfare has been very high. The follow up of the composting process (temperature, volume reduction and compost maturity) and a physicochemical and microbiological analysis of the compost have ensured the proper management of the process. The level of involvement and user satisfaction has been outstanding and the project has presented clear social benefits. Full article