Energy, economic and environmental feasibility of energy recovery from wastewater treatment plants in mountainous areas: A case study of gharyan city – LIBYA

Wastewater treatment plants that are located in high places can provide opportunities for generating sustainable energy, by installing hydroturbines at inlet and exit pipes of wastewater treatment plants, as well as exploiting the sludge resulting from the treatment process as a source for generating biogas, which can be used to generate electric power. Then the treated water is used to irrigate ornamental trees in the roads, gardens and forests, as well as the residues of the fermentation process are used as organic fertilizer and to improve the quality of agricultural soil. In this research, a hybrid system consisting of a hydroelectric station and an electric generator working on biogas was proposed at the wastewater treatment plant in Gharyan. This is because the city is distinguished by its high location, about 713 m above sea level. . The obtained results showed that the proposed hybrid renewable energy system will provide the wastewater treatment plant an electric power of 490 kW, which is sufficient to cover 87.5% of the plant's electrical energy consumption. The amount of treated water was about 13,000 m3/day, and the amount of organic fertilizer was about 17 tons/day. The investment value was estimated at about $1,478,000, and the leveized cost of energy LCOE was estimated at about 2.88 ¢/kWh. The annual net profit from the proposed system is estimated at $307,765/year, and the payback time money at 3.44 years. The proposed system will prevent the release of an annual amount of CO2 gas estimated at 1,886 tons.

As an important grain production area in China, the Northeast Black Soil Region has experienced many problems, such as soil degradation, fertility decline, and grain yield reduction, in recent years. Optimizing fertilizer management is an important measure to maintain and enhance soil fertility. However, improper fertilizer application could aggravate nutrient losses and greenhouse gas N2O emissions, thus leading to soil degradation and environmental pollution. The objectives of the present study were to investigate the response of N2O emission from black soil to long-term application of organic and chemical fertilizers and the key controlling factors. Soil samples （0-20 cm） were collected from a total of nine treatments, including organic fertilizer as the primary treatment （M0- no organic fertilizer； M1- low organic fertilizer； M2- high organic fertilizer） and chemical fertilizer as the secondary treatment （CK- no fertilizer； N- chemical nitrogen fertilizer； NPK- chemical nitrogen, phosphorus, and potassium fertilizer）, in a long-term experiment （32 years） on the black soil of Gongzhuling, Jilin Province. The soil samples were incubated at 25℃ with 65% field water holding capacity for 21 days, and N2O emission and soil physico-chemical biological properties were determined. The results showed that long-term application of organic and chemical fertilizers notably increased N2O emissions from black soil. Compared to those from the M0CK treatment [（0.25±0.01） mg·kg-1, in terms of N, the same as below], the cumulative N2O emissions from the only organic fertilizer treatment significantly increased by 361%-456% [（1.17±0.02） mg·kg-1 and （1.41±0.02） mg·kg-1 for the M1CK and M2CK treatments, respectively]. Furthermore, the N2O emissions strongly increased with increasing organic fertilizer application amounts. Cumulative N2O emissions were significantly higher in the chemical fertilizer treatments by 96%-236% [（0.49±0.01） mg·kg-1 and （0.84±0.03） mg·kg-1 for the M0N and M0NPK treatments, respectively] compared to those in the M0CK treatments. Moreover, the increased N2O emissions due to fertilizers application were significantly larger in the M0NPK relative to M0N treatments. The positive effects of chemical fertilizer application on N2O emission decreased under organic fertilizer amendments （M1 and M2）, indicating that organic fertilizer application alleviated increased N2O emission because of chemical fertilization. The application of organic fertilizers significantly increased bulk soil, aggregate organic carbon （SOC）, total nitrogen （TN）, and soil microbial carbon and nitrogen contents. The application of organic combined with chemical fertilizers further increased SOC and TN contents in bulk soil and aggregates. Pearson correlation and path model analyses showed that the N2O emission was positively correlated with soil carbon and nitrogen fractions and microbial carbon and nitrogen contents among organic and chemical fertilizer treatments. Long-term application of organic and chemical fertilizers strongly regulated N2O emissions via affecting the distribution of carbon and nitrogen contents in soil fractions and changing microbial biomass and substrate availability. In conclusion, the application of organic fertilizers could significantly facilitate N2O emission by increasing the available soil carbon and nitrogen pools as well as microbial carbon and nitrogen contents. The application of organic fertilizers mitigated the positive effects of chemical fertilizers on N2O emissions. Appropriate amounts of organic fertilizers should be used when applying chemical fertilizers, in order to balance the comprehensive effects of fertility improvement with nitrogen loss and greenhouse gas emissions.

On a deeper understanding of data-driven approaches in the current framework of wastewater treatment: looking inside the black-box

Water scarcity is a global challenge faced by millions of people, and it has a negative impact on the ecosystem, public health, and financial stability. Water demand and supply management becomes critical, especially in areas with limited access to clean, safe water. Wastewater and water treatment infrastructure is essential for maintaining environmental integrity and protecting human health. However, water treatment plants in South Africa face various complex obstacles brought on by institutional setups, practical limitations, and environmental concerns, including water quality. This study investigated the institutional arrangements, operational challenges, and environmental concerns that water and wastewater treatment plants face in the Vhembe District Municipality, South Africa. A qualitative study was conducted in Limpopo province, where employees from 12 water and wastewater treatment plants were interviewed, and the data were analyzed thematically. The data were arranged into five major themes using thematic analysis: understanding water and wastewater treatment systems, educational and demographic profile, water quality assessment, operational performance and regulatory compliance, and water volume in waterworks plants. Staff attitudes, institutional and operational challenges, and the current condition of treatment plants were all comprehensively portrayed using Ostrom’s IAD Framework. It was found that workers generally understand water treatment processes, but inconsistencies and a lack of transparency in monitoring water quality were noted, with many parameters from SANS 241 not being tested consistently. A significant educational gap among workers was also observed. Insufficient capacity, load-shedding, limited resources, and inadequate infrastructure prevented treatment plants from meeting daily water needs, worsened by institutional and socio-economic factors. Similar challenges were noted in countries like China, Ethiopia, India, Pakistan, Malaysia, Brazil, and Libya. To enhance water management efficiency and compliance, the study recommends more training, standardized procedures, proactive maintenance, and stakeholder involvement.

Deciphering the antibiotic resistome and microbial community in municipal wastewater treatment plants at different elevations in eastern and western China

Hybrid wastewater treatment system based in a combination of high rate algae pond and vertical constructed wetland system at large scale

Advanced wastewater treatment processes and novel technologies are adopted to improve nutrient removal from wastewater so as to meet stringent discharge standards. Municipal wastewater treatment plants are one of the major contributors to the increase in the global greenhouse gas (GHG) emissions and therefore it is necessary to carry out intensive studies on quantification, assessment and characterization of GHG emissions in wastewater treatment plants, on the life cycle assessment from GHG emission prospective, and on the GHG mitigation strategies. Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants summarises the recent development in studies of greenhouse gases’ (CH4 and N2O) generation and emission in municipal wastewater treatment plants. It introduces the concepts of direct emission and indirect emission, and the mechanisms of GHG generations in wastewater treatment plants’ processing units. The book explicitly describes the techniques used to quantify direct GHG emissions in wastewater treatment plants and the protocol used by the Intergovernmental Panel on Climate Change (IPCC) to estimate GHG emission due to wastewater treatment in the national GHG inventory. Finally, the book explains the life cycle assessment (LCA) methodology on GHG emissions in consideration of the energy and chemical usage in municipal wastewater treatment plants. In addition, the strategies to mitigate GHG emissions are discussed. The book provides an overview for researchers, students, water professionals and policy makers on GHG emission and mitigation in municipal wastewater treatment plants and industrial wastewater treatment processes. It is a valuable resource for undergraduate and postgraduate students in the water, climate, and energy areas; for researchers in the relevant areas; and for professional reference by water professionals, government policy makers, and research institutes. ISBN: 9781780406305 (Print) ISBN: 9781780406312 (eBook) ISBN: 9781780409054 (ePUB)

Towards circular food production systems: Identification of chemical, microbial, and physical food safety hazards in municipal sludge and excess aerobic biomass of the food industry.

Energy, exergy and economic analysis of a novel geothermal energy system for wastewater and sludge treatment

Total concentrations and fractions of Cd, Cr, Pb, Cu, Ni and Zn in sewage sludge from municipal and industrial wastewater treatment plants

Sewage sludge processing and management in small and medium-sized municipal wastewater treatment plant-new technical solution

Municipal wastewater treatment plants (WWTPs) in Gauteng, South Africa, are inadequately designed or optimized to effectively remove microplastics (MPs), resulting in approximately 80% of wastewater being discharged into aquatic ecosystems with insufficient treatment. This study evaluates the prevalence and abundance of MPs in municipal WWTPs and their subsequent introduction into receiving water bodies. Comprehensive sampling was conducted across three municipal WWTPs in the Emfuleni region of Gauteng province from October 2022 to July 2023. Initial MP identification and quantification were performed using light microscopy, while scanning electron microscope energy-dispersive X-ray spectroscopy (SEM/EDS) was employed to identify non-plastic particles and perform elemental analysis. The findings reveal significant seasonal variability in MP concentrations. The highest influent and effluent concentrations were recorded during October (spring), with influent values of 142 MPs/ℓ (WWTP 1), 124 MPs/ℓ (WWTP 2), and 132 MPs/ℓ (WWTP 3), and effluent concentrations of 120 MPs/ℓ (WWTP 1), 63 MPs/ℓ (WWTP 2), and 89 MPs/ℓ (WWTP 3). Conversely, the lowest MP concentrations were observed during April (autumn), with influent concentrations of 114 MPs/ℓ (WWTP 1), 141 MPs/ℓ (WWTP 2), and 78 MPs/ℓ (WWTP 3), and effluent concentrations of 99 MPs/ℓ (WWTP 1), 53 MPs/ℓ (WWTP 2), and 86 MPs/ℓ (WWTP 3). Fibers and filaments constituted the dominant MP morphology, primarily derived from polyester, nylon, and acrylic synthetic textiles. Dark-colored MPs, especially black, blue, and red particles, were predominant in the wastewater samples. This study underscores the critical role of WWTPs as conduits for MP contaminants into the environment and highlights the urgent need to develop and implement improved MP removal technologies in wastewater treatment systems. MP production is estimated to account for approximately 15–20% of total global plastic production, corresponding to an annual generation of approximately 52.5–80 million metric tons of MP. By addressing MP pollution, this research directly contributes to sustainability by promoting the protection of freshwater ecosystems, reducing anthropogenic pressures on aquatic biodiversity, and supporting the principles of sustainable development. The findings align with global and regional goals to enhance water quality management and promote sustainable urbanization practices in line with the United Nations Sustainable Development Goals (SDGs).

The study was carried out to determine the effect of organic and inorganic fertilizers on tomato yield and soil quality. The study was performed in a randomized complete block design consisting of 7 treatments with 3 replications in the research farm, Shaikh Zayed University, Khost, Afghanistan. The fertilizers treatments were T1, organic fertilizer (5 t/ha); T2, organic fertilizer (10 t/ha); T3, urea (150 Kg/ha); T4, urea (200 Kg/ha); T5, mixed fertilizers (organic fertilizer 3 t/ha + urea (100 Kg/ha); T6, mixed fertilizers (organic fertilizer 6 t/ha + urea (70 Kg/ha) and T7 a control. Results indicate that applications of inorganic fertilizers with a combination of organic fertilizers increased tomato yield and improves the nutrient status of the soil. T5 showed the highest yield of tomato and followed by T4 treatment, which were 33.1 and 31.7 t/ha respectively. The lower yield were obtained in T7 and T1 treatments. The highest plant heights (205.0 and 199.0 cm) were obtained in T5 and T4 respectively, while the lowest plant heights were obtained in T1 treatment and followed by T7 treatment. Similarly, we found that a combination of both inorganic and organic fertilizers application also is the best strategy to improve soil nutrients, maintain soil fertility. Soil P2O5 and K2O, where the highest amounts were obtained in T5 and followed by T6, which were 26.5, 22.5 and 44.5 and 41.5 mg/L respectively. The control treatment had the lowest amount of P2O5 and K2O. Therefore, this study suggests that an appropriate amount of organic fertilizer with inorganic fertilizer not only increased tomato yield but also improve soil fertility.

Perfluorinated compounds (PFCs) have drawn much attention due to their environmental persistence, ubiquitous existence, and bioaccumulation potential. Wastewater treatment plants (WWTPs) are fundamental utilities in cities, playing an important role in preventing water pollution by lowering pollution load in waste waters. However, some of the emerging organic pollutants, like PFCs cannot be efficiently removed by traditional biological technologies in WWTPs, and some even increase in effluents compared to influents due to the incomplete degradation of precursors. Hence, WWTPs are considered to be a main point source in cities for PFCs that enter the aquatic environment. However, the mass flow of PFCs from WWTPs has seldom been analyzed for a whole city. Hence, in the present study, 11 PFCs including series of perfluoroalkyl carboxylic acids (PFCAs, C4-C12) and two perfluoroalkyl sulfonates (PFASs, C6 and C8) were measured in WWTP influents and effluents and sludge samples from six municipal WWTPs in Tianjin, China. Generation and dissipation of the target PFCs during wastewater treatment process and their mass flow in effluents were discussed. All the target PFCs were detected in the six WWTPs, and the total PFC concentration in different WWTPs was highly influenced by the population density and commercial activities of the corresponding catchments. Perfluorooctanoic acid (PFOA) was the predominant PFC in water phase, with concentrations ranging from 20 to 170 ng/L in influents and from 30 to 145 ng/L in effluents. Concentrations of perfluoroalkyl sulfonates decreased substantially in the effluent compared to the influent, which could be attributed to the sorption onto sludge, whereas concentrations of PFOA and some other PFCAs increased in the effluent in some WWTPs due to their weaker sorption onto solids and the incomplete degradation of precursors. Perfluorooctane sulfonic acid (PFOS) was the predominant PFC in sludge samples followed by PFOA, and their concentrations ranged from 42 to 169 g/kg and from 12 to 68 g/kg, respectively. Sludge-wastewater distribution coefficients (log K(d)) ranged from 0.62 to 3.87 L/kg, increasing with carbon chain length of the homologues. The mass flow of some PFCs in the effluent was calculated, and the total mass flow from all the six municipal WWTPs in Tianjin was 26, 47, and 3.5 kg/year for perfluorohexanoic acid, PFOA, and PFOS, respectively.

This paper presents the cost optimization of an urban drainage and wastewater treatment system. The mixed sewer urban drainage (including combined sewer overflows and retention basins), the activated sludge wastewater treatment plant (WWTP), and the permissible loading of the receiving water were optimized simultaneously by the nonlinear programming approach. For this purpose, the integrated optimization model OPTIMALWWT was developed. The economic objective function of the defined investment and operational costs is subjected to rigorous design and ecological constraints. A practical example of the cost optimization of an existing urban drainage and WWTP, located in Slovenia, is presented to demonstrate the efficiency of the proposed method. For each of the two different design approaches, three different optimization cases were carried out for three different technological alternatives. As a result, the optimal technological process was finally selected for the reconstruction of the system, as a result of its suitable costs and operational safety.