Wastewater treatment systems and terrorism

Energy and water autarky of wastewater treatment and power generation systems

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

Integrated Life Cycle Assessment and Life Cycle Cost Assessment based fuzzy multi-criteria decision-making approach for selection of appropriate wastewater treatment system

Microplastics from sewage and wastewater treatment facilities can be discharged into rivers and oceans, and the treatment facilities themselves can be a point source of microplastic pollution. The microplastic detection status and methods were compared in Miwon, Cheongju, Jecheon, and Chungju sewage treatment facilities in Chungcheongbuk-do. Samples were collected from the inlet, filtration facility, and discharge of Miwon Sewage Treatment Facility, a Porous Substrate Bioreactor (PSBR) construction corporation. Additionally, the inlet, first settling tank, final settling tank and outlet samples were taken from three sewage treatment facilities (Cheongju, Jecheon, and Chungju), which use bioreactor transformation processes. In the results, raw water showed a range of 232-1,510 pieces/L, and effluent water showed a range of 0.7-6.7 pieces/L. All four sewage treatment facilities showed high treatment efficiency of 98.5-99.9%. The treatment processes showed high removal efficiency in the order of CNR (97.0%) > PSBR (95.9%) > NPR (91.5%) > SMART3 (70.3%). As a study was conducted on only one sewage treatment facility for each process, additional research is necessary.

In recent times, the research trend has shifted towards identifying sustainable energy resources. Bioenergy generation employing wastewater and micro-organisms might be a potential solution to achieve this goal. In microbial fuel cells (MFC), the energy stored in the chemical bonds of contaminants present in wastewater is utilized by the micro-organisms for their metabolism in redox conditions. Furthermore, in this process, free electrons are released into the system, which are captured by the electrodes resulting in the generation of electricity in the external circuit. Hence, the system provides wastewater treatment along with bioenergy generation. However, the system finds difficulty in degrading recalcitrant organic compounds, such as pharmaceuticals and other emerging contaminants, which is possible in constructed wetland (CW) systems. However, CWs require a large footprint area. Recently, combined CW and MFC systems are being used for this purpose due to their resilience and capacity to produce electricity and provide a high level of wastewater treatment. Combined CW-MFC has been found to be more useful than either system alone by complimenting their issues as the redox conditions required for the proper functioning of the MFC system are available in the CW system. Furthermore, the high diversity of micro-organisms present in MFC improves the treatment efficiency of the CW system. This study involves the application of a combined CW-MFC system for the treatment of wastewater and the production of bioelectricity using Lemna minor as macrophyte species. Graphite plates were used as the anode and cathode for electricity production. In order to test the system's effectiveness in terms of removing recalcitrant organic compounds, synthetic wastewater was spiked with 5 mg/L of sulfamethoxazole. The influence of various parameters, such as electrode spacing, the substrate to water depth ratio, and the initial COD concentration of wastewater, was studied. Considerably high removal of around 99% for sulfamethoxazole and 90% for COD removal were observed, along with the production of 133 mV of voltage. It was observed that with the increase in initial COD concentration and substrate to water depth ratio, COD removal also increased. However, an increase in electrode spacing and substrate to water depth ratio after a certain limit showed a negative effect on voltage generation. The entire system could effectively generate bioenergy and treat the sulfamethoxazole-contaminated wastewater.Keywords- Constructed wetlands, Microbial fuel cell, Lemna minor, Emerging contaminants, Bioelectricity

Energy balance performance of municipal wastewater treatment systems considering sludge anaerobic biodegradability and biogas utilisation routes

The present research was conducted to assess the feasibility of biological treatment of a typical wastewater (WW) stream in Multan, Pakistan, using daily trends of WW characteristics and to design a wastewater treatment (WWT) system for that stream. The pH (5.8-6.2), temperature (24-30 °C), biological oxygen demand (BOD5: 128-265 mg/L), ultimate BOD (BODu: 227-438 mg/L), BOD/total Kjeldahl nitrogen (BOD5/TKN:5.9-11.2), BODu/BOD5 (1.6-2.0), carbonaceous BODu/nitrogenous BODu (CBODu/NBODu:1.6-2.8) of the WW was found to support the biological WWT. The inclusion of NBOD also indicated the need for nitrification-denitrification. The linear regression analysis of volatile suspended solids (VSS) with total suspended solids (TSS) indicated the high content of organic solids, which also made the WW suitable for biological treatment. The BOD/COD (chemical oxygen demand) <0.8 indicated the requirement for biomass acclimation. The major process units of the WWT system developed included a primary clarifier, cascade aeration, trickling filter, adsorption filter and chlorination contact tank. During the validation of design procedures, considerable removal of TSS (91%), TDS (46%), BOD5 (88%), COD (87%) was observed over the 15 week operational period of the secondary WWT system. The WWT system developed was appropriate as a sustainable WWT system that consumed less energy and had lower operational costs.

This study was concerned with the economics of supplying an area with water suitable for human consumption. The area chosen for study was the Upper Pawcatuck River Basin in Rhode Island, which has the largest ground water reservoirs in the state. Since the people within and adjacent to the Basin depend exclusively on water from these ground water reservoirs, this study investigated a means of preserving the quality of the ground water so that other methods of supplying water, which might be more costly, would not have to be developed. These other methods would be necessary if the ground water were allowed to become polluted.

Laundry wastewater can be treated in a small-scale aerobic wastewater treatment (WWT) system utilizing a microbubble generator (MBG). However, removing pollutants, precisely chemical oxygen demand (COD), is often low, especially under high wastewater load conditions. This study aims to improve the WWT system’s performance by incorporating an attached growth system. The research was conducted in a small-scale WWT system with a volume of 832 L in Cokrodiningratan, Code Riverbank, Yogyakarta, treating real wastewater from a nearby laundry shop. Experiments were performed batch-wise for one week with suspended and nylon-fabric-attached growth systems. Wastewater samples from the WWT system were taken and analyzed for COD concentrations. Results indicate that the attached growth system outperforms the suspended growth system. During operation, the suspended growth system achieved a COD removal rate of approximately 78% (temperature range of 26-28°C, a pH level of 6.3-7.1, and influent COD: 377.5 mg/L). In contrast, with the introduction of attachment media under similar batch operation conditions (temperature range: 26-28°C, pH level: 6.4-7.4, influent COD: 755.5 mg/L), the COD removal efficiency increased to 94%. The incorporation of attachment media led to a notably stable performance outcome.

Soil-based onsite wastewater treatment systems (OWTS) are becoming more important for the treatment and disposal of wastewater in areas that do not have central wastewater collection and treatment systems. However, there are concerns that OWTS may have adverse effects on public health and environment. The purpose of this study is to treat wastewater using a natural soil column in order to evaluate treatment system performance. Wastewater was applied to two different natural soils at different flow rates of 9, 18 and 36 L/day. The treatment performances of wastewater and geotechnical properties of the natural soils were examined. As a result of this study, the percentage of COD and SS removal in wastewater after soil column filtration ranged from 36.2% to 80.5% and 84.4% to 97.9% respectively. pH values of wastewater after the filtration were measured at between 7.75 and 8.12. TP and TN removal rates were found in the range of 23.9-76.8% and 12.4-83.0%, respectively. The column effluent water was classified as both 'high hardness class' in terms of hardness and 'polluted water' in terms of conductivity. Column effluent water was found in 'low, medium, and high hazard' classes in terms of SAR. Whereas the PL values of the natural soils were found to increase by up to 4.8% in the filtration area, specific gravity decreased by nearly 1.1%. The values of LL, PI, maximum dry density, optimum water content, and permeability changed depending on the soil type. The UCS of the natural soils after wastewater filtration decreased by about 5.9%. It was concluded that natural soils have positive effects on treatment of wastewater in a short time.

Novel approaches of flocculant application in sewage treatment

Bio‐electro‐Fenton processes use biological electrons produced from bioelectrochemical systems to treat wastewater. The most significant advantages of bio‐electro‐Fenton systems are high effectiveness, low toxicity, gentle operation conditions, environmentally friendly treatment without sludge accumulation and energy conservation. Though promising, bio‐electro‐Fenton systems still face several challenges, such as high power density, H2O2 concentration, cathode materials, Fe2+ concentration and pH. This review comprehensively discusses the mechanisms of bio‐electro‐Fenton systems. Then, structural configurations are critically reviewed, including microbial fuel cells coupled with electro‐Fenton systems, microbial electrolysis cells coupled with electro‐Fenton systems and other bioelectrochemical systems coupled with electro‐Fenton systems. Furthermore, recent advances in bio‐electro‐Fenton systems for wastewater treatment are introduced, including dye solution, pharmaceuticals and personal care products, oily wastewater, landfill leachate and other pollutants. In addition, the current challenges and specific future prospects of bio‐electro‐Fenton, such as possible mechanisms for improving the power output, electrode materials that are potentially useful, self‐designed electrodes and methods of maintaining circumneutral pH values, are also explored. Heretofore, great progress in bio‐electro‐Fenton has been made, but further improvements are still needed in order to make this system more economical and practical. © 2020 Society of Chemical Industry

Antibiotic contamination attracts growing concerns because of their deleterious effects on the ecosystem and human health. In this study, 43 antibiotics in wastewater from a variety of sources and water of the Yangtze River in Chongqing City in western China were measured. Thirty compounds were detected, and their concentrations were highest in leachates from the municipal solid waste treatment facilities (landfills and incineration plants) with total concentrations of 3584-57,106ng/L. The total concentrations in influents of municipal and industrial wastewater treatment plants (WWTPs) were comparable (401-7994ng/L versus 640-8945ng/L). The concentrations in raw sewage from swine farms (with a total of 10,219-39,195ng/L) and poultry farms (1419-36,027ng/L) were noticeably higher than those from other farms (54.0-5516ng/L). Fluoroquinolones were the dominant antibiotics contributing over 50% in all the sources, and sulfonamides and imidazole fungicides contributed 3.2-34%, whereas tetracyclines and macrolides had minor contributions. The overall antibiotic removal rates were highest in solid waste treatment facilities (88% on average), comparable between municipal and industrial WWTPs (61%), and lowest in animal farms (39%). The mass loads to the investigated municipal WWTPs via influent wastewater ranged from 7.80 to 1531kg/year (53.2-2482μg/day per capital). The influent mass loads to the industrial WWTPs and farms were 3.7-50kg/year and 0.9-5437g/year, respectively. We estimated that the mass inventories of antibiotics from these sources to the environment via effluent discharges were approximately 2044kg for municipal WWTPs, 61kg for industrial WWTPs, and 34kg for animal farms in the whole city. Antibiotic concentrations in the Yangtze River water were substantially low (< 492ng/L, with a mean of 57.8ng/L) suggesting dissipation during the movement.

Occurrence and removal of PPCPs in municipal and hospital wastewaters in Greece

Aging wastewater collection and treatment systems have not received as much attention as other forms of infrastructure, even though they are vital to public health, economic growth, and environmental quality. Inflow and infiltration (I&I) are among potentially widespread problems facing central sewage collection and treatment systems, posing risks of sanitary system overflows (SSOs), system degradation, and water quality impairment, but remain poorly quantified. Whole-system analyses of I&I were conducted by regression analyses of system flow responses to rainfall and temperature for 93 wastewater treatment plants in 23 counties in eastern North Carolina, USA, a coastal plain region with high water tables and generally higher rainfalls than the continental interior. Statistically significant flow responses to rainfall were found in 92% of these systems, with 2-year average I&I values exceeding 10% of rainless system flow in over 40% of them. The effects of rainfall, which can be intense in this coastal region, have region-wide implications for sewer system performance and environmental management. The positive association between rainfall and excessive I&I parallels the effects of storm water runoff on water quality, in that excessive I&I can also drive SSOs, thus confounding water quality protection efforts.