Municipal Wastewater Treatment Sludge Research Articles

Turkey’s Municipal Solid Waste and Urban Waste Water Treatment Sludge Electrical Energy Potential

The role of indigenous and renewable energy resources is crucial for countries that want to be less dependent on foreign countries. Renewable energy resource power plants have many advantages when compared with other resources. They make countries less energy dependent and they also have environmentally friendly technologies when compared with other resources. Turkey is a country that has an abundance of renewable energy resources and biomass is one of the most promising energy resources in renewables. The goal of this paper is to determine Turkey’s electricity potential based on industrial wastes i.e. municipal solid waste (MSW) and urban wastewater treatment sludge potential, using applicable electricity generation methods. In this attempt, electrical energy potential of these resources has been found by using applicable waste to energy methods, technical and economical parameters. Electrical energy potential of Biogas (Landfill gas included) based on these resources is an amount of 6.73 billion kWh/year. Municipal solid waste (MSW) and dried municipal wastewater treatment sludge electrical energy potential is an amount of 23.81 billion kWh/year. Based on the resources stated; using the biogas and biomass energy values, calculations resulting in primary energy potentials; the installed capacity for gas-motor systems, gas turbine systems (Simple cycle), gas & steam turbine systems (combined) and boiler – steam turbine systems have been determined.

Higher concentrations of microplastics in runoff from biosolid-amended croplands than manure-amended croplands

Land-applied municipal biosolids, produced from municipal wastewater treatment sludge, contributes to microplastics contamination in agroecosystems. The impacts of biosolids on microplastic concentrations in agricultural soil have been previously investigated, however, the potential for microplastics transport from biosolid-amended croplands has not been previously quantified. In this study, manure and biosolids were applied to field plots, runoff was collected following natural precipitation events and the potential of bacterial biofilm to grow on different microplastic morphologies was investigated. Higher concentrations of microplastics were detected in runoff from plots with land-applied biosolid in comparison with manure-amended and control plots. Fibers and fragments were the most frequently detected plastic morphologies in runoff, correlated with their decreased surface roughness. The potential of biosolids to contribute to microplastic contamination to U.S. surface waters was quantified which is among the first to quantify the potential for nonpoint source microplastic contamination of surface waters adjacent to agricultural production areas.

Biodegradation of Propylene Glycol Wastewater Using Bacterial Consortia Isolated from Municipal Wastewater Treatment Sludge–Process Kinetics and Optimization

Propylene glycol (PG), commonly used in the food, cosmetics and pharmaceutical industries and considered non-PBT, is still an emerging contaminant of concern due to its widespread use. In this study, an isolate of a bacterial consortium obtained from an effluent treatment plant, MC1S, was used to degrade PG. The growth kinetics of the isolate was studied under aerated and non-aerated conditions. The isolate was able to effectively grow in saline water under aerated conditions using PG as the substrate. Using response surface methodology (RSM), the effect of pH, salinity, PG concentration, phosphate and nitrate concentration on cell growth and PG degradation was investigated. The isolated bacterium, MC1S, was capable of degrading PG with a maximum of 79% COD reduction observed and was able to withstand comparatively high salinity of the medium. Solution pH and salinity were the most important parameters affecting degradation. Salinity less than 0.1 M and pH close to 8 appeared to be the optimum conditions for PG degradation. HPLC analysis of the treated sample appeared to show the presence of three daughter products. Using RSM, a quadratic equation model between COD reduction and the process variables was developed. The results indicated that aerobic treatment of PG under specific conditions was the best approach for the specific isolate.

Fate of per- and polyfluoroalkyl substances (PFAS) during hydrothermal liquefaction of municipal wastewater treatment sludge

PFAS sorbed to sludge degrade to varying degrees when sludge is subjected to hydrothermal liquefaction for production of liquid fuel.

Mixed culture polyhydroxyalkanoate (PHA) synthesis from nutrient rich wet oxidation liquors

Organic waste residues can be hydrothermally treated to produce organic acid rich liquors. These hydrothermal liquors are a potential feedstock for polyhydroxyalkanoate (PHA) production. We investigated the effect of dissolved oxygen concentration and substrate feeding regimes on PHA accumulation and yield using two hydrothermal liquors derived from a mixture of primary and secondary municipal wastewater treatment sludge and food waste. The enriched culture accumulated a maximum of 41% PHA of cell dry weight within 7 h; which is among the highest reported for N and P rich hydrothermal liquors. Recovered PHA was 77% polyhydroxybutyrate and 23% polyhydroxyvalerate by mass. The families Rhodocyclaceae (84%) and Saprospiraceae (20.5%) were the dominant Proteobacteria (73%) in the enriched culture. The third most abundant bacterial genus, Bdellovibrio, includes species of known predators of PHA producers which may lead to suboptimal PHA accumulation. The PHA yield was directly proportional to DO concentration for ammonia stripped liquor (ASL) and inversely proportional to DO concentration for low strength liquor (LSL). The highest yield of 0.50 Cmol PHA/Cmol substrate was obtained for ASL at 25% DO saturation. A progressively increasing substrate feeding regime resulted in increased PHA yields. These findings demonstrate that substrate feeding regime and oxygen concentration can be used to control the PHA yield and accumulation rate thereby enhancing PHA production viability from nutrient rich biomass streams.

Comparison of Scenedesmus acuminatus and Chlorella vulgaris cultivation in liquid digestates from anaerobic digestion of pulp and paper industry and municipal wastewater treatment sludge

Two microalgae, Chlorella vulgaris and Scenedesmus acuminatus, were batch cultivated separately in two types of diluted liquid digestates. The first digestate (ADPP) was obtained from a mesophilic laboratory digester treating biosludge from a pulp and paper industry wastewater treatment plant. The second digestate (ADMW) was collected from a full-scale mesophilic anaerobic digester treating-mixed municipal wastewater treatment sludge. The highest biomass production (as volatile suspended solids, VSS), 8.2–9.4 g L−1, was obtained with S. acuminatus in ADPP. C. vulgaris in ADMW had the lowest biomass production, reaching 2.0 g L−1. Both microalgae removed ammonium efficiently from ADPP (99.9% removal) while the final ammonium removal efficiencies from ADMW with S. acuminatus and C. vulgaris were only 44.0 and 23.8%, respectively. The phosphate removal efficiencies from both ADPP and ADMW were higher than 96.9% with both microalgae. The highest carbohydrate content (60.5%) was obtained with S. acuminatus cultivated in ADPP. Scenedesmus acuminatus in ADPP showed one of the highest biomass production yields that have been reported for microalgae in real wastewater-derived nutrient sources. Consequently, this combination is promising for developing biorefinery and biofuel applications in the pulp and paper industry.

Benthic communities in inland salinized waters with different salinities and nutrient concentrations and the ecology of Chironomus aprilinus (Diptera: Chironomidae) in the Czech Republic

The macrozoobenthos in saline pools at dumps in a former coal mining area was studied over a period of two years. Due to specific environmental conditions these pools are unique in the Czech Republic. Extremely high values of salinity (up to 11‰) along with a low concentration of dissolved phosphorus (0.01-0.1 mg.l-1) are typical of some of the water in this area. The pools were grouped into three categories based on their conductivity values and treated using cow dung, municipal wastewater treatment sludge and inorganic NPK (nitrogen-phosphorus-potassium) fertilizer at doses recommended for carp ponds. The application of fertilizer had a positive effect on the density and biomass of all the groups in the macrozoobenthos. The highest and the lowest increases in macrozoobenthos biomass were recorded after the application of NPK and cow dung, respectively. However, the application of fertilizer had no effect on the diversity of macrozoobenthos. Chironomus aprilinus, recorded in the Czech Republic for the first time, inhabited all pools with conductivity ranges of between 5,000-16,000 µS.cm-1. The density of C. aprilinus larvae increased with increasing salinity reaching a maximum of about 17,083 ind.m-2 (biomass - 82 g.m-2). Analysis of C. aprilinus phenology revealed a bivoltine pattern with the summer generation of larvae reaching a maximum in June-July and the overwintering generation in October to November.

Enhanced biogas production from anaerobic co-digestion of municipal wastewater treatment sludge and fat, oil and grease (FOG) by a modified two-stage thermophilic digester system with selected thermo-chemical pre-treatment

Anaerobic co-digestions with fat, oil and grease (FOG) were investigated in two-stage thermophilic (55 °C) semi-continuous flow co-digestion systems. One two-stage co-digestion system (System I) was modified to incorporate a thermo-chemical pre-treatment of pH = 10 at 55 °C, which was the best pre-treatment condition for FOG co-digestion identified during laboratory-scale biochemical methane potential (BMP) testing. The other two-stage co-digestion system (System II) was operated without a pre-treatment process. The anaerobic digester of each digestion system had a hydraulic retention time (HRT) of 24 days. An organic loading rate (OLR) of 1.83 ± 0.09 g TVS/L·d was applied to each digestion system. It was found that System I effectively enhanced biogas production as the thermo-chemical pre-treatment improved the substrate hydrolysis including increased COD solubilization and VFA concentrations. Overall, the modified System I yielded a 25.14 ± 2.14 L/d biogas production rate, which was substantially higher than the 18.73 ± 1.11 L/d obtained in the System II.

The influence of temperature and moisture contents regimes on the aerobic microbial activity of a biosolids composting blend.

To understand the relationships between temperature, moisture content, and microbial activity during the composting of biosolids (municipal wastewater treatment sludge), well-controlled incubation experiments were conducted using a 2-factor factorial design with six temperatures (22, 29, 36, 43, 50, and 57 degrees C) and five moisture contents (30, 40, 50, 60, and 70%). The microbial activity was measured as O2 uptake rate (mg g(-1) h(-1)) using a computer controlled respirometer. In this study, moisture content proved to be a dominant factor impacting aerobic microbial activity of the composting blend. Fifty percent moisture content appeared to be the minimal requirement for obtaining activities greater than 1.0 mg g(-1) h(-1). Temperature was also documented to be an important factor for biosolids composting. However, its effect was less influential than moisture content. Particularly, the enhancement of composting activities induced by temperature increment could be realized by increasing moisture content alone.

Discovery of a 137Cs Hot Particle in Municipal Wastewater Treatment Sludge

Analysis of primary treatment sludge from a municipal wastewater treatment plant revealed elevated 137Cs concentrations in one sample. This elevated activity was associated with a radioactive particle that, when isolated and quantified, was found to contain 1.82 kBq of 137Cs. Additional analysis indicated an absence of alpha activity, and energetic beta radiation, if present, was less than the 137Cs activity. The particle was approximately 50 microns in diameter, appeared not to be an aggregate, and was nonmetallic.

Quantitative extraction of linear alkylbenzenesulfonates using supercritical carbon dioxide and a simple device for adding modifiers

Quantitative extraction of anionic surfactants, linear alkylbenzenesulfonates (LAS), from soil, sediment, and municipal wastewater treatment sludge was achieved using a simple apparatus for the preparation of high concentrations of organic modifiers in supercritical CO 2. The method allows several different modifiers to be tested without the necessity of mixing modifiers in the pump or purchasing pre-mixed fluids. Of the several modifiers tested, methanol yielded the best extraction efficiencies, and >90% recoveries of LAS were achieved using a 30-min extraction at 380 atm with ca. 40 mol % methanol in CO 2. Extraction efficiency versus time plots for 14C-labeled and native LAS showed good agreement, indicating that the spiked LAS was representative of the native LAS.

State Programs to Control Municipal Sludge

State controls on the disposal and utilization of municipal wastewater treatment sludge are cataloged and analyzed. Data gathered through reviews of documented state regulations and guidelines, and supplemented by contacts with state officials, is summarized for sludge landfilling, landspreading, distribution and marketing, thermal processing, ocean dumping, and lagoons/stockpiling. Results point to the states' track record of following federal leads in developing sludge management programs. State programs are noted to focus on the more common disposal and utilization practices of landfilling and landspreading, while other widely practiced operations, including distribution of marketing of sludge, remain largely uncontrolled.