Central Wastewater Treatment Plant Research Articles

Beneath Biscayne Bay

To improve the reliability and resiliency of one of its most critical wastewater components, the Miami-Dade Water and Sewer Department replaced more than a mile of aging force main used to convey flows to its Central District Wastewater Treatment Plant. Installation of the new force main required constructing two large vertical shafts and a large-diameter tunnel beneath a portion of Florida’s Biscayne Bay.

Vitellogenin concentrations in feral Danish brown trout have decreased: An effect of improved sewage treatment in rural areas?

Feminization of male and juvenile fish because of exposure to estrogens or estrogenic chemicals in effluents from central wastewater treatment plants (WWTPs) is a worldwide issue of concern. Intersex and induction of the female yolk protein, vitellogenin, in male and juvenile fish are robust biomarkers for estrogenic exposure, and feminized fish have been observed downstream of WWTP outlets in many countries. Danish central WWTPs reduce effluent estrogenicity effectively by advanced sewage treatment, and feminizations have not been observed downstream of central WWTP outlets. However, between 2000 and 2004, investigations of Danish streams not receiving sewage from central WWTPs revealed a high variation in vitellogenin concentrations of male juvenile brown trout (Salmo trutta); some individuals had high concentrations, probably as a result of estrogenic point sources, and the plasma concentration was >50 ng mL-1 in 79% of the juvenile males. The streams were reinvestigated in 2010 to 2016, and the average male level had decreased to a hitherto unseen baseline level; in 2010 only 0.7% (one individual) of the males had a vitellogenin concentration >50 ng mL-1 , which could indicate that the estrogenicity of the streams decreased after 2004. We examined possible estrogenic sources in streams unaffected by central WWTP effluents, and found that the reduced vitellogenin levels are most likely explained by a national effort to improve on-site wastewater treatment in scattered houses not connected to central WWTPs. Environ Toxicol Chem 2018;37:839-845. © 2017 SETAC.

DEVELOPMENT OF A COMPUTER PROGRAMME FOR THE DESIGN OF MUNICIPAL WASTEWATER TREATMENT FACILITIES Part 5: Secondary Clarifier

A computer programme was developed using Fortran programming language utilizing IBM-PC compatible microcomputers to design a secondary clarifier in a centralised municipal wastewater treatment plant. The programme is used to design the dimension and capacity of four circular secondary clarifiers including the influent and effluent structure to satisfy the specified design criteria such as the detention time, the overflow rate, solid-loading rates and weir loading. The programme was written in a subroutine called from the main programme which also be able to call other subroutines for designing other facilities in the treatment plant. The programme runs successfully given the right input data. The results are easy to interpret and automatically appear either on the computer screen or in an output file

Full-scale wastewater treatment plant simulation for real-time optimization

Abstract A dynamic simulation model has been developed and validated for the 1.4 million p.e. capacity Budapest Central Wastewater Treatment Plant to support intensification, process development and risk assessment. By the integration of both the biological and physico-chemical processes the technological design of separated units becomes possible as well as the exploration of the connections within the system. The calibration of the model parameters for an operating treatment plant is the key requirement for the proper application of dynamic simulation tool to optimize operational and maintenance conditions and specify the potential development areas. We have done a one-year period of validation which included sensitivity analysis and the simulation of time intervals in the same way as in the calibration process. At the same time we investigated the suitability of the simulation system for real-time operation optimization. As conclusion we ascertained that due to the computational power necessity of a properly detailed model, it is not applicable for real-time operation optimization, nevertheless it is suitable for the detection of the system reactions for long-term changes of the influent load. This means that a properly functioning model is applicable for indicating the development directions.

Pollution control and cost analysis of wastewater treatment at industrial parks in Taihu and Haihe water basins, China

It is becoming increasingly important to control the discharge of industrial wastewater from industrial parks in order to reduce water pollution. In this study, a comprehensive investigation of water treatment at industrial parks in two large basins in China was carried out, involving comparative and correlation analysis of wastewater quality, pollutant removal, sludge production and cost. In both basins, the average influent chemical oxygen demand, ammonia, and total nitrogen at the centralized wastewater treatment plants in chemical parks were higher than those in comprehensive parks. Anaerobic-anoxic-oxic and anoxic-oxic were the most widely used treatment processes at both comprehensive and chemical parks in the two basins—similar to municipal wastewater treatment plants in China. The operating costs of centralized wastewater treatment plants in the comprehensive and chemical parks comprised the following components: electricity > labor > chemical costs. Reductions in chemical oxygen demand, ammonia and total nitrogen and total phosphorus in the centralized wastewater treatment plants in the parks led to an average reduction of 28% in total pollutants in municipal and industrial wastewater in the two basins. These results could have supports for the design and optimization of wastewater treatment processes, as well as for evaluation of how centralized wastewater treatment plants can help to control water pollution.

Ammonium removal in landfill leachate using SBR technology: dispersed versus attached biomass.

Large concentrations and oscillations of ammonium nitrogen (NH4+-N) in municipal landfill leachate pose considerable constraints to its further treatment in central wastewater treatment plants. The aim of this study was to evaluate and optimize two technologies for the pre-treatment of 600 L/day of landfill leachate: in particular, to optimize their operational conditions for NH4+-N removal up to a level appropriate for discharge to sewers, i.e. <200 mg/L. Both technologies were based on a sequencing batch reactor (SBR), with two different biomass processes: (A) SBR with dispersed/flocculated biomass and (B) SBR with biomass attached to carriers. The results revealed that both technologies successfully reduced the NH4+-N from 666 mg/L (on average) at the inflow to below 10 mg/L at the outflow with alkalinity adjustment in a 12-hour cycle. Both technologies achieved 96% removal efficiencies for NH4+-N. However, SBR with dispersed biomass showed higher flexibility under varying conditions due to the shorter adaptation time of the biomass.

The impact of temporal variability of excess sludge characteristics on the effects obtained in the process of its ultrasonic disintegration

ABSTRACTThis paper aimed to indicate the characteristics of excess sludge, which have the greatest impact on the effects obtained during its ultrasonic disintegration (UD). The direct and technological effects observed after sludge disintegration and anaerobic digestion (AD) depend on the factors affecting the quality of its matrix and simply on the parameters of a disintegrator. Sludge samples originate from a Central Waste Water Treatment Plant in Gliwice, and were collected after mechanical thickening by a monthly period. This approach allowed to observe the temporal changes of sludge characteristics, in a continuous manner. To evaluate the achieved disintegration effects, the following indicators were used: degree of disintegration (DDCOD) and the author's indicators describing the direct and technological effects of UD (IDi, ITi, ITd), based on the changes in the sludge characteristics. Disintegration was carried out by means of an ultrasonic device equipped with a thin sonotrode. AD was conducted under mesophilic conditions for 20 days. Statistical analysis confirmed that the most important parameters of sludge, which determine obtained effects, were total and volatile solids, capillary suction time, concentration of chemical oxygen demand and pH value. The investigations have also showed that the increase in sludge temperature during its disintegration has a significant impact on the magnitude of other effects obtained in the process.

Comparison of N2O Emissions and Gene Abundances between Wastewater Nitrogen Removal Systems.

Biological nitrogen removal (BNR) systems are increasingly used in the United States in both centralized wastewater treatment plants (WWTPs) and decentralized advanced onsite wastewater treatment systems (OWTS) to reduce N discharged in wastewater effluent. However, the potential for BNR systems to be sources of nitrous oxide (NO), a potent greenhouse gas, needs to be evaluated to assess their environmental impact. We quantified and compared NO emissions from BNR systems at a WWTP (Field's Point, Providence, RI) and three types of advanced OWTS (Orenco Advantex AX 20, SeptiTech Series D, and Bio-Microbics MicroFAST) in nine Rhode Island residences ( = 3 per type) using cavity ring-down spectroscopy. We also used quantitative polymerase chain reaction to determine the abundance of genes from nitrifying () and denitrifying () microorganisms that may be producing NO in these systems. Nitrous oxide fluxes ranged from -4 × 10 to 3 × 10 µmol NO m s and in general followed the order: centralized WWTP > Advantex > SeptiTech > FAST. In contrast, when NO emissions were normalized by population served and area of treatment tanks, all systems had overlapping ranges. In general, the emissions of NO accounted for a small fraction (<1%) of N removed. There was no significant relationship between the abundance of or genes and NO emissions. This preliminary analysis highlights the need to evaluate NO emissions from wastewater systems as a wider range of technologies are adopted. A better understanding of the mechanisms of NO emissions will also allow us to better manage systems to minimize emissions.

Treatment of high organic carbon industrial wastewater using photocatalysis process

In Thailand, agricultural machinery manufacturing companies are known to generate high organic carbon wastewater from painting and leak testing processes. Chemical oxygen demand (COD) value in leak test wastewater is found to be in the range of 3000–5000mg/l. In this study, three scales including lab-scale, pilot-scale and industrial-scale photocatalytic reactors were developed to investigate the efficiency of wastewater treatment. In lab-scale, the 800ml reactors were set up to optimize the best condition for pH and TiO2 loading. The results suggested that the pH had no effects on the COD removal, whereas the COD removal efficiency was increased by TiO2 loading. The highest COD removal efficiency of 85% was found at the TiO2 loading of 1g/l. The 200l reactor of pilot-scale and the 3000l reactor of industrial-scale were established and continuously operated for 30days. The results revealed that the COD removal efficiency was >90%, and the COD concentration was reduced to 250–300mg/l in the treated wastewater. The COD value of treated wastewater met the standard set by the Industrial Estate Authority of Thailand to discharge into a central wastewater treatment plant, which verified the successful implementation of process to the actual industrial wastewater.

Chemical fingerprinting of saline water intrusion into sewage lines.

High salinity in sewage sludge can affect not only the operation of wastewater treatment plants (WWTPs) but also the quality of treated water generated, thereby limiting its downstream reuse. Using data on geochemical parameters, both for the central WWTP in Abu Dhabi, UAE, and literature values for potential regional saline water sources (e.g., shallow groundwater and regional Arabian Gulf seawater), a variety of chemical fingerprinting diagnostic ratios were calculated and plotted in order to determine the source of salinity in the municipal sewage. Data were compared with data from a regional WWTP that was not impacted by salinity. Monitoring data demonstrated persistently elevated levels of salinity in the municipal wastewater arriving at the central WWTP from the city. Dilution/concentration analysis using a conductivity vs. chloride plot showed both potential sources, i.e. Arabian Gulf seawater and coastal hypersaline groundwater, as feasible sources of wastewater salinization. Further diagnostic analysis using a Panno Plot indicated that coastal groundwater was the only likely source of salinization of municipal sewage. Additional confirmation of the identity of the source and the extent of mixing using different lines of evidence like stable isotope ratios is recommended for future study.

Sustainability of decentralized wastewater treatment technologies

In many Countries, small communities are required to treat wastewater discharges to increasing standards of lesser environmental impacts, but must achieve that goal at locally sustainable costs. While biological membrane treatment (membrane bio-reactors (MBRs)) is quickly becoming the industry standard for centralized wastewater treatment plants, and would also be ideally suited also for small plants potentially subject to relatively large hydraulic load variations, its investment and operating costs are usually high for that class of applications. Consequently, small treatment plants are generally configured as anoxic or aerated biological tanks with little sedimentation, making them quite susceptible to hydraulic loads transient and sludge quality changes. As an alternative, Constructed Wetlands Systems (CWSs) are gradually and successfully being introduced in many Countries. CWSs are designed to utilise the natural functions of wetland vegetation, soils and their microbiological populations to treat wastewater. Pretreatment occurs by filtration and settling, followed by bacterial decomposition in a natural-looking lined marsh. A new technology, a new type of membrane-like aerobic reactor initially designed for the degradation of hydrocarbon-derived groundwater contaminants, was recently tested for treating domestic, with performance similar to that of MBRs. Examples from the above applications are illustrated and compared in this paper. The paper also discusses merits and drawbacks of the various illustrated technologies, in view of their sustainability potential, and according to the new development paradigms for urban water systems, that encourage the development of local water-cycle clusters with local reuse and recycle of the resource, and possible local recovery of energy and/or materials.

Comparison of Fenton process and adsorption method for treatment of industrial container and drum cleaning industry wastewater

ABSTRACTThe present study aims to explore the characterization of industrial container and drum cleaning (ICDC) industry wastewater and treatment alternatives of this wastewater using Fenton and adsorption processes. Wastewater derived from ICDC industry is usually treated by chemical coagulation and biological treatment in Turkey and then discharged in a centralized wastewater treatment facility. It is required that the wastewater COD is below 1500 mg/L to treat in a centralized wastewater treatment facility. The wastewater samples were characterized for parameters of pH, conductivity, COD, BOD5, TSS, NH3-N, TN, TOC, TP, Cd, Cr, Cu, Fe, Ni, Pb, Zn, and Hg. Initial COD values were in the range of 11,300–14,200 mg/L. The optimum conditions for Fenton treatment were 35–40 g/L for H2O2, 2–5 g/L for Fe2+, and 13–36 for H2O2/Fe2+ molar ratio. The optimum conditions of PAC doses and contact times in adsorption studies were 20–30 g/L and 5–12 h, respectively. Removal efficiencies of characterized parameters for the three samples were compared for both Fenton and adsorption processes under optimum conditions. The results suggest that these wastewaters are suitable for discharge to a centralized wastewater treatment plant.

A Study to Distinguish Between Wastewater Treatment Plants in Rural Egypt

Several wastewater treatment plants technologies have been set up in the Egyptian villages; however, the most efficient and economical technology hasn't been determined. This research aims to distinguish between the wastewater treatments plants which are used in rural Egypt to find out the best between them. The data about Centralized and Decentralized wastewater treatment plants which are used in rural Egypt using group of factors has been collected to distinguish between the characterizations of these plants by doing a questionnaire to evaluate the weight of these factors. The questionnaire has been given to experts to evaluate the factors for getting relative weights of them. Expert evaluated the factors according to his importance by choosing a mark from the lowest value one to the highest value ten. After receiving the results of the questionnaire from the experts, the data were processed to find out the best group of results of these plants. The largest percentage of Relative Weights of factors is Efficiency, followed by Costs, Average load removed, Specific surface area, Average flow and Average population. The best three centralized wastewater treatment plants were from the aerobic treatment.

Investigation of dissolved N&lt;sub&gt;2&lt;/sub&gt;O production processes during wastewater treatment system in Ulaanbaatar

Nitrous oxide (N2O) is an increasing greenhouse gas in the troposphere and a potential destroyer of stratospheric ozone layer. Wastewater treatment plant (WWTP) is one of the anthropogenic N2O sources because inorganic and organic nitrogen compounds are converted to nitrate (NO3-, in the case of standard system) or N2 (in the case of advanced system) by bacterial nitrification and denitrifcation processes in WWTP. These major processes can be distinguished by isotopocule analysis. In order to reveal production mechanisms of N2O in a standard wastewater treatment, we made water sampling at the central WWTP in Ulaanbaatar. The water samples collected from seven stations including biological reaction tanks were measured for concentration and isotopocule ratios of dissolved N2O and other inorganic nitrogen. Dissolved N2O concentration was extremely higher than that expected under atmospheric equilibrium (about 9 nmol/l) at all stations, indicating that this system is a potential source of N2O. It showed a gradual increase with the progress of biological reaction and the highest concentration (335.7 nmol/l) was observed at station N5-4 of the aeration tank when the DO was 5.7 mg/l. Nitrification by nitrifying bacteria could actively occur by the concentration of NH4+ decreased whereas NO2- and NO3- showed a temporal and monotonic increase, respectively, under high DO concentration. Although the reported values of site preference (SP) of N2O, the difference in 15N/14N ratio between central (α) and terminal (β) nitrogen, produced via NO2- reduction (SP(ND)), including both nitrifier and denitrifier denitrification, and NH2OH oxidation (SP(HO)) ranged from -10.7‰ to 0‰ and 31.4‰ to 36.3‰, respectively, the observed SP at aeration tank was close to SP(ND) rather than SP(HO). It was ranged from 0.4‰ to 13.3‰ when N2O concentration was high, implying that the NO2- reduction made a greater contribution to N2O production. Slightly elevated SP (13.3‰) only at station N5-1 was derived from the mixing of N2O produced via NH2OH oxidation and the maximal contribution of this pathway was estimated to be about 40%. In other words, the contribution of NO2- reduction was more than 60%.

Sequential anaerobic-aerobic biological treatment of colored wastewaters: case study of a textile dyeing factory wastewater.

In the present study the feasibility of the use of a bacterial batch sequential anaerobic-aerobic process, in which activated sludge was used in both parts of the process, for pretreatment of wastewater generated by a textile dyeing factory has been considered. Activated sludge used in the process was obtained from a municipal wastewater treatment plant and adapted to real dyeing wastewater using either an anaerobic-only or an anaerobic-aerobic process over a period of 90 days. The use of activated sludge adapted using the anaerobic-aerobic process resulted in a higher overall decolorization efficiency compared to that achieved with activated sludge adapted using the anaerobic-only cycles. Anaerobic and aerobic periods of around 34 and 22 hours respectively resulted in an effluent with chemical oxygen demand (COD) and color content which met the standards for discharge into the centralized wastewater treatment plant of the industrial estate in which the dyeing factory was situated. Neutralization of the real dyeing wastewater and addition of carbon source to it, both of which results in significant increase in the cost of the bacterial treatment process, was not found to be necessary to achieve the required discharge standards.

Investigation of the environmental impacts of municipal wastewater treatment plants through a Life Cycle Assessment software tool

ABSTRACTThis paper investigates the total and per capita environmental impacts of municipal wastewater treatment in the function of the population equivalent (PE) with a Life Cycle Assessment (LCA) approach using the processes of the Ecoinvent 2.2 database available in the software tool SimaPro v.7.3. Besides the wastewater treatment plant (WWTP), the study also considers the sewerage system. The obtained results confirm that there is a ‘scale factor’ for the wastewater collection and treatment even in environmental terms, in addition to the well-known scale factor in terms of management costs. Thus, the more the treatment plant size is, the less the per capita environmental impacts are. However, the Ecoinvent 2.2 database does not contain information about treatment systems with a capacity lower than 30 PE. Nevertheless, worldwide there are many sparsely populated areas, where it is not convenient to realize a unique centralized WWTP. Therefore, it would be very important to conduct an LCA study in order to compare alternative on-site small-scale systems with treatment capacity of few PE.

Environmental impact assessment of centralized municipal wastewater management in Thailand

Urbanization and industrial development intensify water utilization and wastewater generation. The efficiency of wastewater treatment systems varies and depends on system design and wastewater condition. The research aims to examine seven existing centralized municipal wastewater treatment plants (WWTPs) in Bangkok to discover which system configuration yields the best environmental and economic performance. The degree of environmental impact and operational costs from different system designs were investigated to help select future wastewater treatment systems. Life cycle assessment (LCA) has been conducted to evaluate environmental impacts from centralized municipal wastewater treatment systems. Life cycle impact assessment method based on endpoint modeling (LIME) was applied, with three major potential environmental impact categories including eutrophication, global warming, and acidification. All seven centralized municipal WWTPs in Bangkok were investigated as case studies. The system configurations are classified into five types of activated sludge (AS) systems. The contribution of impacts from individual processes in each type of AS system was analyzed. The methodology covered major on-site and off-site operational processes excluding construction and maintenance phases. Average annual data were calculated to develop an inventory dataset. JEMAI-Pro software was utilized in this study to analyze the life cycle impact of the systems. The level of environmental impact from a WWTP depends on the configuration of the AS system. The highest potential environmental impact from a municipal WWTP is eutrophication, which is obviously affected by ammonium and phosphorous discharges into water bodies. The vertical loop reactor activated sludge (VLRAS) system yielded the best treatment performance among the five AS sub-systems. The consumption of electricity used to operate the system contributed significantly to global warming potential and correlated considerably with operating costs. Comparing among three system sizes, the large-scale WWTP revealed inefficient electricity consumption, whereas the medium plant provided better performance in chemical use and operating costs. Centralized municipal WWTPs with capacities ranging from 10 to 350 × 103 m3/day were evaluated with respect to environmental performance and costs during the operating phase. Among all case studies, a medium-scale WWTP with a VLRAS system offered the best operating performance in terms of low environmental impact, resource consumption, and cost. To enhance WWTP management, it is vital to improve the efficiency of electricity consumption in primary and secondary treatment processes and increase wastewater collection efficiency to maximize the plant operating capacity and minimize overall environmental impacts.

Anaerobic digestion of aliphatic polyesters.

Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry.

Contribution to Exemplary In-house Wastewater Heat Recovery in Berlin, Germany

Thermal energy recovery from wastewater can be established from centralized wastewater treatment plants and sewage systems. Little attention has been given to In-house wastewater; although it can potentially pave way towards a sustainable heat source. The study was conducted inside student hostels in Berlin, in which water supply, wastewater, and room temperatures variations were observed during winter for one month. It was shown that water supply temperature has insignificant effect on the variations of in-house wastewater temperature as compared to room temperature and water use. The daily average temperature of the in-house wastewater was in a range of 11°C to 20°C, with an average of about 15°C. It was illustrated that by selecting suitable combination of heat exchanger and heat pump, about 40 kWh/h (917 kWh/day) average in- house wastewater thermal heat can be recovered and about 230 €/day saved. This can contribute to reduction of energy needed for hot water provision by about 30% in the targeted hostels.

Performance evaluation of membrane bioreactor for treating industrial wastewater: A case study in Isfahan Mourchekhurt industrial estate

Aims: The aim of this study was to evaluate a membrane bioreactor (MBR) system for optimization effluent quality by feeding of the influent (raw wastewater and anaerobic reactor effluent) in Isfahan - Mourchekurt Industrial Estate Centralized Wastewater Treatment Plant. Materials and Methods: The MBR was equipped with two flat sheets membrane with 0.2 μm pore size, were operated in parallel style and feed simultaneously with raw industrial wastewater (MBR1) and anaerobic reactor effluent (MBR2). The average organic loading rates in two reactors were 1.37 and 0.52 (kg chemical oxygen demand [COD]/m 3 .day), respectively. All analyses were implemented according to the standard methods procedure. Results: The average concentration of COD was lower than 100 mg/L and 50 mg/L in both reactor effluent, respectively, and it was 1000 MPN/100 mL for MBR1 and these were Conclusion: The MBR technology was used to treat the combined industrial wastewater was efficient, and its effluent can be perfectly used for water reuse. The MBR performance was improved by applying an anaerobic pretreatment unit.