Search Results (54)

To address the slow growth rate of photosynthetic bacteria (PSB), this study introduces pantothenic acid as a biological enhancing factor. The effects of pantothenic acid on PSB proliferation and its effectiveness in treating high-concentration ammonia–nitrogen wastewater were systematically evaluated. Additionally, the effects of different culture conditions, including dark aeration, darkness, light exposure, and light aeration, on PSB growth were investigated. The results show that optimal PSB growth was achieved with 20 mg/L of pantothenic acid; however, higher concentrations of pantothenic acid inhibited bacterial growth. The addition of pantothenic acid also significantly enhanced the performance of PSB in treating high-concentration organic wastewater, increasing the removal rates of COD, ammonia nitrogen, total phosphorus, and total nitrogen to 43.0%, 94.0%, 49.7%, and 51.0%, respectively. Furthermore, a synergistic effect between dark aeration and light exposure was observed. When the time of light and dark aeration was set at 1:1, the highest PSB yield was recorded, and the removal efficiencies of COD, ammonia nitrogen, total nitrogen, and total phosphorus increased to 71.4%, 95.3%, 57.1%, and 74.7%, respectively. Through the introduction of pantothenic acid and optimization of culture mode, the rapid growth of PSB and highly efficient treatment of organic wastewater were achieved, providing a new approach for advanced wastewater treatment and resource utilization. Full article

Sanitary landfill leachate treatment was evaluated using magnetite-catalyzed ozone, an upflow anaerobic sludge blanket (UASB) reactor, and microalgae, both individually and in combination, to improve biodegradability and remove organic matter, solids, metals, and nutrients. Leachates were characterized before and after each treatment, and their impacts on methanogenic activity, aerobic toxicity, and the BOD₅/COD ratio were assessed. Magnetite-catalyzed ozone pretreatment enhanced biodegradability, enabling an optimal coupling point with the UASB at 40 min when the specific methanogenic activity reached 0.22 g CH₄-COD/(gVSS·d). The UASB achieved COD removal rates of up to 75%, but high concentrations were maintained in the effluent with low ammoniacal nitrogen and phosphorus removal rates. Microalgae promoted nutrient removal, reducing total nitrogen and phosphorus by up to 65% and 70%, respectively, although with lower efficiency in terms of organic matter removal. Process coupling demonstrated that ozonation followed by UASB application improved anaerobic degradation, whereas the use of microalgae after biological treatment optimized the final effluent quality. Despite the improvements achieved, the final values for some parameters still exceeded the discharge limits, indicating the need for operational adjustments or additional treatments to ensure effective purification. Full article

This study presents the long-term performance evaluation of a full-scale hybrid membrane bioreactor (MBR)–nanofiltration (NF) system for the treatment of high-strength municipal landfill leachate from the Istanbul–Şile Kömürcüoda facility. Over a 16-month operational period, influent and effluent samples were analyzed for key parameters, including chemical oxygen demand (COD), ammonium nitrogen (NH₄⁺-N), total phosphorus (TP), suspended solids (SS), and temperature. The MBR unit consistently achieved high removal efficiencies for COD and NH₄⁺-N (93.5% and 98.6%, respectively), while the NF stage provided effective polishing, particularly for phosphorus, maintaining a TP removal above 95%. Seasonal analysis revealed that the biological performance peaked during spring, likely due to optimal microbial conditions. To support intelligent control strategies, artificial neural network (ANN) models were developed to predict effluent COD and NH₄⁺-N concentrations using influent and operational parameters. The best-performing ANN models achieved R² values of 0.861 and 0.796, respectively. The model’s robustness was validated through RMSE, MAE, and 95% confidence intervals. Additionally, Principal Component Analysis (PCA) and Random Forest algorithms were employed to determine the parameter importance and nonlinear interactions. The findings demonstrate that the integration of hybrid membrane systems with AI-based modeling can enhance treatment efficiency and forecasting capabilities for landfill leachate management, offering a resilient and data-driven approach to sustainable operation. Full article

Pollution caused by N and P is a significant contributor to water eutrophication. While traditional biological treatment processes can remove some N and P elements from water, the effluent quality often fails to meet the stringent requirements of sensitive areas. The autotrophic denitrification’s simultaneous nitrogen and phosphorus removal pro-cess, known for its low operating cost and minimal sludge production, has garnered considerable attention from researchers. In this study, natural pyrite was used for the removal of nitrogen and phosphorus in a denitrification system, and the underlying mechanisms were elucidated. The results indicate that the N and P removal efficiency was influenced by empty bed contact time (EBCT) and the pH value. The highest NO₃⁻-N removal rate of 90.24% was achieved at an EBCT of 8 h, while the PO₄³⁻-P removal rate reached 81.58% at an EBCT of 12 h. The addition of a carbon source enhanced the synergistic autotrophic/heterotrophic denitrification, significantly improving phosphorus removal with an increasing C/N ratio. Microbial characteristics analysis revealed that, at the phylum level, Chlorobiota, Bacteroidota, and Chloroflexota played a crucial role in heterotrophic autotrophic denitrification. At the genus level, Thauera, Aridibacter, and Gemmatimonas were key players in heterotrophic denitrification, while Thiobacillus, Rhodoplanes, and Geobacter were associated with autotrophic denitrification. Full article

In this study, we aimed to investigate the effects of coagulants and dissolved organic matter (DOM) on the biological toxicity of nano-zinc oxide (nZnO) to key microorganisms involved in biological phosphorus removal during sewage treatment. Polyaluminum chloride and polyferric chloride were selected as coagulants, whereas fulvic acid, glucose, and aspartic acid represented the DOM. The mechanisms through which these chemicals influence nZnO toxicity were also investigated. The results show that polyaluminum chloride and polyferric chloride effectively reduced nZnO toxicity in phosphorus-accumulating organisms, demonstrating their detoxification effects. Similarly, fulvic acid and glucose mitigated nZnO toxicity, whereas aspartic acid displayed dual effects: detoxification at low concentrations and enhanced toxicity at high concentrations. These findings highlight the dual role of sewage treatment additives in enhancing traditional pollutant removal and mitigating the nanoparticle-induced inhibition of microbial biochemical processes. This study clarified the interactions between coagulant chemicals, DOM, and nanoparticles in sewage treatment, offering insights into the regulatory mechanisms that improve treatment efficacy and reduce ecological risks. Full article

An integrated hybrid system was developed, incorporating sedimentation, anaerobic digestion, biological filtration, and a two-stage hybrid subsurface flow constructed wetland, horizontal subsurface flow constructed wetland (HSSFCW) and vertical subsurface flow constructed wetland (VSSFCW), to treat rural sewage in southern Jiangsu. To optimize nitrogen and phosphorus removal, the potential of six readily accessible industrial and agricultural waste byproducts—including plastic fiber (PF), hollow brick crumbs (BC), blast furnace steel slag (BFS), a zeolite–blast furnace steel slag composite (ZBFS), zeolite (Zeo), and soil—was systematically evaluated individually as substrates in vertical subsurface flow constructed wetlands (VSSFCWs) under varying hydraulic retention times (HRTs, 0–120 h). The synergy among substrates, plants, and microbes, coupled with the effects of hydraulic retention time (HRT) on pollutant degradation performance, was clarified. Results showed BFS achieved optimal comprehensive pollutant removal efficiencies (97.1% NH₄⁺-N, 76.6% TN, 89.7% TP, 71.0% COD) at HRT = 12 h, while zeolite excelled in NH₄⁺-N/TP removal (99.5%/94.5%) and zeolite–BFS specializing in COD reduction (80.6%). System-wide microbial analysis revealed organic load (sludges from the sedimentation tank [ST] and anaerobic tanks [ATs]), substrate type, and rhizosphere effects critically shaped community structure, driving specialized pathways like sulfur autotrophic denitrification (Nitrospira) and iron-mediated phosphorus removal. Annual engineering validation demonstrated that the optimized strategy of “pretreatment unit for phosphorus control—vertical wetland for enhanced nitrogen removal” achieved stable effluent quality compliance with Grade 1-A standard for rural domestic sewage discharge after treatment facilities, without the addition of external carbon sources or exogenous microbial inoculants. This low-carbon operation and long-term stability position it as an alternative to energy-intensive activated sludge or membrane-based systems in resource-limited settings. Full article

This study investigates the influence of varying nitrogen-to-phosphorus (N:P) ratios on the growth, nutritional composition, and nutrient removal efficiency of Wolffia globosa under controlled laboratory conditions. Six treatments with N:P ratios of 1:3, 1:2, 1:1, 2:1, 3:1, and a control were evaluated. The findings indicate that a balanced N:P ratio (1:1) promotes optimal growth, resulting in the highest biomass yield and specific growth rate (SGR = 0.120 g/day). In contrast, a nitrogen-rich ratio (3:1) enhanced protein accumulation and phosphorus removal, while the 2:1 ratio favored nitrogen uptake. These results reflect underlying physiological responses, including nitrogen assimilation and phosphorus uptake mechanisms regulated by nutrient balance. A trade-off was observed between biomass production and phosphorus removal efficiency, suggesting that different N:P ratios may be suited to specific application goals. This study contributes to a more comprehensive understanding of how macronutrient balance affects growth and metabolism in W. globosa and offers practical implications for optimizing its use as both a sustainable protein source and a biological agent for nutrient remediation in wastewater treatment systems. Full article

Purple phototrophic bacteria (PPB) offer a sustainable approach for biological wastewater treatment while simultaneously producing valuable by-products such as polyhydroxyalkanoates (PHAs). This study investigates the effects of continuous light wavelengths over a two-stage nutrient reduction setup on PHA accumulation in a mixed PPB culture grown on fuel synthesis wastewater (FSW). The first stage promoted biomass production under nutrient availability, while the second stage targeted the enhancement of PHA accumulation through nitrogen (N) or phosphorus (P) reduction. Biomass growth remained stable under P reduction but significantly increased under N reduction. The results showed that organics removal efficiency decreased under nutrient reduction, particularly under P reduction, while N reduction conditions enhanced P uptake from the media. Maximum PHA accumulation reached 12.6% CDW under N reduction and 10.0% CDW under P reduction. Light type played a dominant role, with a full-spectrum light that included ultraviolet (UV) and infrared (IR) promoting the highest PHA accumulation, whereas white light with far-red wavelengths (700–770 nm) enhanced biomass growth. These findings highlight the potential of optimizing light conditions and nutrient availability to enhance PHA biosynthesis, paving the way for improved bioplastic production from wastewater streams. Full article

The discharge of wastewater into bodies of water and subsoil poses a serious pollution problem. In many neighborhoods or districts, there are often no wastewater treatment systems due to the high costs involved, which may compromise human health. Constructed wetlands (CWs) offer an ecological solution to improve water quality and enable its reuse. They promote the removal of contaminants through physical, chemical, and biological processes. The objective of this study was to evaluate Canna hybrids, Zingiber spectabile, and Alpinia purpurata—ornamental plants not typical of wetlands—regarding their function as phytoremediators and their growth under such conditions. Utilizing CWs with ornamental plants for water treatment in neighborhoods could improve the adoption of this ecotechnology. To this end, eight cells were built: two were controls (without plants), two contained Canna hybrids, two had Zingiber spectabile, and two included Alpinia purpurata, all designed for a hydraulic retention time of three days. Inlet and outlet water samples were collected biweekly for six months. The results showed that the cells with Canna hybrids and Zingiber spectabile removed from 40 to 70% of total nitrogen and phosphorus. In terms of organic matter, measured as COD and TSS, the removals ranged from 55 to 90%. In contrast, cells with Alpinia purpurata demonstrated removal rates of only 30 to 50%, which were statistically lower (p ≤ 0.05), indicating a slower adaptation to wetland conditions. This slower adaptability is directly related to the growth of the species, as Alpinia purpurata also exhibited the lowest growth rates. The study concluded that using CWs with the studied ornamental plants is a viable alternative for treating wastewater and, at the same time, they may add a commercial value to the vegetation. Additionally, they can enhance the aesthetic landscape with colorful flowers that attract birds and insects and the treated water could be utilized to irrigate sports areas or urban planters. Full article

The issue of environmental pollution caused by wastewater discharge from fruit juice production has attracted increasing attention. However, the cost-effectiveness of conventional treatment technology remains insufficient. In this study, a gravity-driven membrane bioreactor (GDMBR) was developed to treat real fruit juice wastewater from secondary sedimentation at pressures ranging from 0.01 to 0.04 MPa without requiring backwashing or chemical cleaning, with the aim of investigating flux development and contaminant removal under low-energy conditions. The results demonstrate an initial decrease in flux followed by stabilization during long-term filtration. Moreover, the stabilized flux level achieved with the GDMBR at pressures of 0.01 and 0.02 MPa was observed to surpass that obtained at 0.04 MPa, ranging from 4 to 4.5 L/m⁻² h⁻¹. The stability of flux was positively associated with the low membrane fouling resistance observed in the GDMBR system. Additionally, the GDMBR system provided remarkable efficiencies in removing the chemical oxygen demand (COD), biological oxygen demand (BOD), ammonia (NH₄⁺-N), and total nitrogen (TN), with average removal rates of 82%, 80%, 83%, and 79%, respectively. The high biological activity and microbial community diversity within the sludge and biofilm are expected to enhance its biodegradation potential, thereby contributing to the efficient removal of contaminants. Notably, a portion of total phosphorus (TP) can be effectively retained in the reactor, which highlighted the promising application of the GDMBR process for actual fruit juice wastewater based on these findings. Full article

Phosphorus (P) discharge from anthropogenic sources, notably sewage effluent and agricultural runoff, significantly contributes to eutrophication in aquatic environments. Stringent regulations have heightened the need for effective P removal technologies in wastewater treatment processes. This paper provides a comprehensive review of current P removal methods, focusing on both biological and chemical approaches. Biological treatments discussed include enhanced biological P removal in activated sludge systems, biological trickling filters, biofilm reactors, and constructed wetlands. The efficiency of microbial absorption and novel biotechnological integrations, such as the use of microalgae and fungi, are also examined. Chemical treatments reviewed encompass the application of metal salts, advanced oxidation processes such as chlorination, ozonation, and the Fenton reaction, as well as emerging techniques including the Electro-Fenton process and photocatalysis. Analytical methods for P, including spectrophotometric techniques and fractionation analyses, are evaluated to understand the dynamics of P in wastewater. This review critically assesses the strengths and limitations of each method, aiming to identify the most effective and sustainable solutions for P management in wastewater treatment. The integration of innovative strategies and advanced technologies is emphasized as crucial for optimizing P removal and ensuring compliance with environmental regulations. Full article

When using runoff infiltration devices to remove nitrogen and phosphorus pollutants from urban runoff, the quality of the effluent is affected by the length of dry spells between rain events. This study presents a novel analysis of how these dry periods impact the device’s effectiveness in removing pollutants and the resulting biological succession within the filter. Our analysis examines nitrogen and phosphorus removal in a rainwater filtration context, providing new insights into how dry period duration influences infiltration system performance. The results indicate that biological processes have a significant impact on reducing total nitrogen (TN) and total phosphorus (TP) contents under different drying periods. A 3-day drying period is most effective for reducing TN through biological processes, while a 7-day period is best for TP reduction. This suggests that moderately extending the drying period improves TP removal efficiency but does not enhance TN removal. The dominant bacterial phylum responsible for denitrification and phosphorus removal is Proteobacteria, with Pseudomonas and Acinetobacter as the leading genera. As the drying period lengthens, the dominant genera shift from Pseudomonas to Massilia. At a 3-day drying period, denitrification primarily occurs through Pseudomonas on the surfaces of maifanite and zeolite. At a 7-day dry-out period, Acinetobacter is mainly responsible for phosphate removal on maifanite surfaces. However, after a 14-day dry-out period, both biomass and bioactivity of Pseudomonas and Acinetobacter decrease, leading to reduced efficiency in removing nitrogen and phosphorus pollutants from runoff infiltration devices. These results aid in developing runoff infiltration devices for specific scenarios and offer crucial guidance for regulating runoff pollution control technologies. Full article

The work presents the concept of aerobic granular sludge (AGS) and its potential for wastewater treatment. The work also evaluates the condition of the SBR (Sequencing Batch Reactor) type of municipal wastewater-treatment plant (WWTP) after its reconstruction into a system with AGS. The WWTP parameters achieved before and after reconstruction were compared. Operational measurements of the process during the individual phases of the treatment process showed a balanced concentration profile of the monitored parameters in the span of the semicontinuous cycle. Laboratory tests showed that the sludge from the WWTP has nitrification and denitrification rates comparable to the rates achieved for flocculent sludge, and it is also comparable to the nitrification and denitrification rates of AGS with size of granules below 400 µm. Despite the fact that complete sludge granulation was not achieved, the results measured at the WWTP confirmed the advantages of the AGS concept. Neither anaerobic nor anoxic conditions were identified in the SBR during the individual phases of operation, yet high removal efficiencies of ammonia and nitrate nitrogen and orthophosphate phosphorus were achieved. The concentration of ammonia and nitrate nitrogen at the WWTP effluent was below 5 mg/L, and the concentration of phosphorus was below 0.5 mg/L. Full article

With the emphasis on climate change and society’s goals of carbon neutrality, wastewater treatment plants (WWTPs) are facing new challenges to be more sustainable and particularly to reduce their greenhouse gas (GHG) emissions. In addition, the increasingly stringent discharge standard, especially the phosphorus removal target, also puts lots of pressure on WWTPs. The key solution is to tailor and/or optimize the phosphorus management strategies to balance removal targets and sustainability. As such, the present study systematically summarizes and analyzes different phosphorus management approaches and their impacts on the costs and operation of whole plants. The summary shows that precipitate scaling is a common issue that can be alleviated by proper phosphorus management strategies and operation optimization. Biological phosphorus removal and chemical phosphorus removal processes have their respective advantages and disadvantages. Most importantly, each phosphorus removal process probably has countering impacts on wastewater and sludge treatment lines. Thus, the evaluation of a specific phosphorus removal process should consider all factors in choosing a suitable technology, which is also true for phosphorus recovery, and the recovery from incineration ash seems to be a trend that is more feasible from a regulatory perspective. Full article

Recovering phosphorus (P) through combustion from waste streams, like wastewater sludge and animal manure, offers a promising solution. This research explores the P release patterns in different ashes derived from secondary raw materials, using a long-term soil incubation lasting 160 days. The study evaluated the P release dynamics in five types of ashes from enhanced biological phosphorus removal (EBPR) systems and pig slurry burned at different temperatures. According to the results, a primary effect was observed on P bioavailability during the initial incubation period. All tested ashes release more than 50% of the total P applied between days 5 and 10. Ashes from EBPR exhibited higher P release than those from pig manure, indicating ash origin as a key factor in P release. Additionally, combustion temperature was crucial, with higher temperatures resulting in increased P release rates. Furthermore, the Pearson correlation revealed a strong relationship between the characteristics of the ashes and the amount of P release. Overall, these findings suggest that ashes could be a valuable P-source for agriculture avoiding the process of wet chemical P extraction, thus reducing both economic and environmental costs. Full article