Design Of Wastewater Treatment Plants Research Articles

In-vitro multiparametric analysis of imipenem resistance in bacteria caused by acquisition of foreign DNA and natural mutations

Several studies have demonstrated that antimicrobial resistance (AMR) can result from natural mutations or the acquisition of foreign antimicrobial resistance genes. Many environmental parameters are known to affect AMR, including trace antibiotic concentrations in water, pH, hydraulic retention time, and nutrient concentration, among others. However, most analyses that investigate these parameters analyze them independently. This study investigated the development of natural resistance in Salmonella sp., and the horizontal transfer of resistance genes from an imipenem- resistant (IR) E. coli strain under varying environmental conditions. An automated continuous-culture device was employed to investigate the effect of external parameters of relevance to wastewater treatment plants and to conduct a multiparametric analysis to determine the relative importance of the different variables. In terms of mutation-driven resistance, hydraulic retention time, trace antibiotic concentration, and initial cell concentrations are the leading factors contributing to higher IR in Salmonella spp. In the case of acquired resistance, the initial trace antibiotic concentrations, and hydraulic retention times were also important, but pH, initial nutrient concentration, and, very importantly, the initial concentration of IR E. coli, were the leading factors contributing to IR in Salmonella spp. These results point out some important factors that need to be considered during the design and operation of wastewater treatment plants to minimize the appearance and transmission of antibiotic resistance.

Impacts of projected future changes in precipitation on wastewater treatment plant influent volumes connected by combined sewer collection systems

Climate change induced precipitation changes can impact wastewater influent volumes and, in turn, the design and operation of wastewater treatment plants (WWTPs). As influent volumes approach or exceeds the design capacity of the WWTP, the likelihood of poor treatment or untreated discharges that result in environmental damage, increases. To date, there has been a lack of research analysing the impact changes in precipitation may have on influent volumes of WWTPs with combined sewerage systems. This study leverages data driven models of observed precipitation and influent volumes for 14 Irish WWTPs with combined sewerage systems, to project monthly wastewater influent volumes in 2041 – 2060 using Ireland’s most up-to-date high resolution multi-model RCM projections under RCPs 4.5 and 8.5. With changing monthly average daily precipitation, influent volumes for all the WWTPs demonstrated maximum decreases during summer months for both RCP 4.5 and RCP 8.5. Winter months showed increasing trends in influent volumes, particularly under RCP 8.5. The results indicate that with projected increase in high and very high precipitation days in Ireland (under CMIP5), the return periods for influent volumes that exceed the hydraulic capacity of 5 of the WWTPs will reduce. This work also presents a framework by which newer high-resolution downscaled climate models can be used to developed updated impact analysis of changing rainfall patterns on wastewater. It likely that wastewater treatment infrastructure will need to adapt to more intense precipitation to minimise the occurrence of combined sewer overflows.

Solutions for urban sanitation: A case study of Imhoff tank technology in Bandung, Dutch East Indies (1917‒1938)

This research investigates how municipalities managed wastewater in the Dutch East Indies in the early 20th century. We focus on Bandung, one of the most important cities in the Dutch East Indies, which transformed into a modern residential area, economic center, and seat of government. This research combines primary data from written sources and field observations using historical-archaeological methods. The written sources include official reports from the Public Works Department, Civil Health Department, Bandung City Council, old maps, sewer network designs, environmental engineering journals, and newspapers published from 1909 to 1941. Using the techno-environmental approach introduced by Martin V. Melosi, this study considers urban technology as a strategic response by decision-makers to address the challenges faced by developing cities in the early 20th century. The study reveals that Bandung City faced environmental problems, such as the natives' habit of defecating in rivers and open spaces, spreading diseases, and potentially polluting river water. These problems arose due to the lack of sanitation facilities and the densely populated settlements, especially in the native and Chinese residential areas. To address these challenges, policymakers, environmental engineers, and researchers initiated the design and implementation of sewers, public toilets, and wastewater treatment plants in 1917. The Municipality integrated sewers with the Imhoff Tank sewage treatment technology developed by researchers and engineers from 1932 to 1938 to introduce circular sewage treatment. Imhoff Tanks was a significant technological innovation in the Dutch East Indies. In the early 20th century, only a handful of cities in the Dutch East Indies, including Bandung, Medan, and Yogyakarta, had integrated sewer networks. Among the cities that did have sewer networks, Bandung pioneered the implementation of the Imhoff Tank. As a result, it emerged as an important laboratory and development center for Bandung and the entire Dutch East Indies. The Imhoff Tank treatment process, which produces clean water, fertilizer, and methane gas that can be used as vehicle fuel, was part of a proactive strategy pioneered by policymakers in Bandung in the early 20th century, reflecting their vision to create a healthy and sustainable city.

A comprehensive comparison of microbial communities between aerobic granular sludge and flocculent sludge for nutrient removal in full-scale wastewater treatment plants

Understanding the microbial community structure of sludge is crucial for improving the design, operation and optimisation of full-scale wastewater treatment plants (WWTPs). This study aimed to have a comprehensive comparison of microbial communities between aerobic granular sludge and flocculent sludge from two full-scale sequential batch reactors-based WWTPs with nutrient removal for the first time. To better understand key functional bacteria such as polyphosphate accumulating bacteria (PAOs), competitive bacteria such as glycogen accumulating bacteria (GAOs) and nitrifying bacteria for both nitrogen and phosphorus removal, another two full-scale WWTPs with only carbon (C) removal and C and nitrogen (N) removal were compared too. It was found that the richness and diversity of the microbial population in sludge increased with pollutant removal from only C, C and N, to C,N, P removal. For C, N P removal, granule structure led to a more diverse and rich microbial community structure than flocculent structure. Although more abundant nitrifying bacteria were enriched in granular sludge than flocculent sludge, the abundance of total putative PAOs was equivalent. However, the most typical putative PAOs such as Tetrasphaera and Candidatus Accumulibacter seemed to be more correlated with biological phosphorus removal performance, which might be more proper to be used as an indication for P removal potential. The higher abundance of GAOs in flocculent sludge with better phosphorus removal performance might suggest that further investigation is needed to understand the functions of GAOs. In addition, the equivalent abundances of PAOs in the WWTPs with only C removal and with C, N, and P removal, respectively, indicate that many newly reported putative PAOs might not contribute to P removal. This study provides insight into the microbial communities and functional bacteria in aerobic granular sludge and flocculent sludge in full-scale SBRs, which can provide microbes-informed optimisation of reactor operation for better nutrient removal.

Excess of Nutrients in Prefabricated or Compact Wastewater Treatment Plants: Review, Solution Alternative, and Modeling for Verification

Chile has numerous areas that lack sewage collection, including in the capital city. Sanitation in these cases is managed through individual solutions like septic tanks or small wastewater treatment plants (WWTPs) that use biological treatment, usually activated sludge with extended aeration. In general, the design of these systems adheres to the quality standards mandated by regulations for discharge, infiltration, or irrigation. In this scenario, traditional methods like increasing dissolved oxygen (DO) or hydraulic retention time (HRT) were unable to effectively reduce excessive nutrients. Therefore, literature related to nutrient excess and denitrification systems is consulted and reviewed to compile different solutions suitable for the presented issue. Potential solutions were modeled and verified using the free simulation software WRc STOAT. The software accurately predicted the unsatisfactory results of the current setup and provided parameters for the proposed modifications. Experience, precise user definition, influential characteristics, and modeling are essential in the design of WWTPs.

Machine learning assisted combined systems of wastewater treatment plants with constructed wetlands optimal decision-making

This study proposed an efficient framework for optimizing the design and operation of combined systems of wastewater treatment plants (WWTP) and constructed wetlands (CW). The framework coupled a WWTP model with a CW model and used a multi-objective evolutionary algorithm to identify trade-offs between energy consumption, effluent quality, and construction cost. Compared to traditional design and management approaches, the framework achieved a 27 % reduction in WWTP energy consumption or a 44 % reduction in CW cost while meeting strict effluent discharge limits for Chinese WWTP. The framework also identified feasible decision variable ranges and demonstrated the impact of different optimization strategies on system performance. Furthermore, the contributions of WWTP and CW in pollutant degradation were analyzed. Overall, the proposed framework offers a highly efficient and cost-effective solution for optimizing the design and operation of a combined WWTP and CW system.

Energy and resource recovery from a future aerobic granular sludge wastewater treatment plant and benefit analysis

The sustainable approach to energy and resource recovery from excess sludge is gaining traction. This study compared the benefits of methane production through anaerobic digestion (AD) and the recovery of alginate-like exopolymers (ALE)/phosphorus (P) from two types of aerobic granular sludge (AGS). Bacterial and algal-bacterial AGS produced similar methane amounts, around 292 and 287 mL/g-VSadded, respectively, over 30 days, with 72% and 80% biodegradability. After ALE extraction, the remaining AGS showed a 48–56% decrease in methane production without pH adjustment. However, a conceptual wastewater treatment plant (WWTP) processing 10,000 m3/d of wastewater with ALE/P and methane recovery yielded the highest net profits, approximately 66.3 thousand USD annually, when algal-bacterial AGS was used, compared to 59.2 thousand USD for the bacterial AGS-based WWTP. These findings provide valuable insights for developing a sustainable wastewater industry and future WWTP design.

Fuzzy Approach for Evaluating Critical Factors in the Design and Construction of Conventional Wastewater Treatment Plants

Fuzzy Approach for Evaluating Critical Factors in the Design and Construction of Conventional Wastewater Treatment Plants

Exploring stochastic differential equation for analyzing uncertainty in wastewater treatment plant-activated sludge modeling

Abstract The management of wastewater treatment plant (WWTP) and the assessment of uncertainty in its design are crucial from an environmental engineering perspective. One of the key mechanisms in WWTP operation is activated sludge, which is related to the biological oxygen demand (BOD) parameter. In the modeling of BOD, the conventional approach utilizing ordinary differential equations (ODEs) fails to incorporate the stochastic nature of this parameter, leading to a considerable level of uncertainty in the design of WWTP. To address this issue, this study proposes a stochastic model that utilizes stochastic differential equations (SDEs) instead of ODE to simulate BOD activities of microorganisms and wastewater flow rate (Q). The SDEs and integral It̂o are solved using the Euler–Maruyama method for a period of 15 sequential days and the timespan of 2019–2020 for a WWTP in Tabriz City. SDE improves the design of WWTP facilities by identifying uncertainties and enhancing reliability. This, in turn, increases the reliability of the technical structures within the WWTP and improves the performance of its biological system. By considering the randomness of the problem, the proposed method significantly improves the results, with an enhancement of 11.47 and 10.11% for the BOD and Q models, respectively.

Wastewater treatment plant design and modeling for the city of Erzurum

Currently large amounts of wastewater are produced by domestic and industrial activities. Discharge of wastewater to the receiving environment without treatment causes significant health and environmental problems. Modeling and optimization of Wastewater Treatment Plants (WWTP) developed to treat domestic wastewater play key roles in determining unit components, design parameters and operation conditions. Several models were proposed to predict the treatment performance in WWTP. The Activated Sludge Model No. 1 (ASM1) is one of the commonly-used standard models developed to better understand removal of carbonaceous and nitrogenous materials. In this study, a WWTP is proposed for domestic wastewater using grit chamber, circular primary and secondary clarifiers, completely-mixed aeration tank, sludge thickener, sludge dewatering and anaerobic digestion processes together. The WWTP was modeled with ASM1 noting the topographic and meteorological features of the city. The treatment performances with wastewater temperatures of 10°C and 20°C were investigated for this plant, operating at high elevation. Removal efficiencies at 20°C were 95.7%, 92.2%, 97.9% and 99.2% for MLSS, COD, BOD and NH4, while effluent concentrations were 14.83, 48.51, 6.55 and 0.3 mg L-1, respectively. At 10°C, removal efficiencies were 88.9%, 88%, 93.2%, and 26.9%, while effluent concentrations were 38, 75, 21.83 and 26.13 mg L-1, respectively. A clear reduction was observed in nitrogenous material removal at low temperatures. Additionally, keeping dissolved oxygen concentration in the aeration tank at 1.5 mg L-1 with PID control increased nitrification efficiency by 30%. The findings reveal the importance of modeling studies during planning of WWTP.

Increase metabolic heat to compensate for low temperature in activated sludge systems

The efficient operation of activated sludge systems is frequently hindered by low temperatures, and extensive research has been conducted to overcome this difficulty. However, the effect of varying temperatures on heat generation during substrate degradation remains unclear. In this study, results from laboratory-scale reactors show that sludge generated 5.36 ± 0.58 J/mg COD, 4.45 ± 0.24 J/mg COD, and 4.22 ± 0.26 J/mg COD at 10 °C, 20 °C, and 30 °C under aerobic conditions, respectively. Similarly, the sludge generated 4.05 ± 0.31 J/mg COD, 2.37 ± 0.15 J/mg COD, and 2.89 ± 0.18 J/mg COD under anoxic conditions. Despite the decreased respiration rates and hence reduced pollutant removal efficiency, sludge exhibited effective heat generation at low temperatures. Results from the full-scale plant also show a negative correlation between the heat generation capacity of microorganisms and the temperatures. 14.2 °C is considered the critical wastewater temperature for microorganisms' heat generation to offset the investigated plant's heat dissipation. This observation verified that thermal compensation for low temperatures was also significant in the full-scale plant. The mechanism of low-temperature compensation is attributed to non-growth processes being less dependent on temperature than growth processes, resulting in slow microbial growth but high heat generation at low temperatures. These findings provide valuable insights into the design and sustainable operation of wastewater treatment plants.

Simultaneous enhanced removal of pharmaceuticals and hormone from wastewaters using series combinations of ultra-violet irradiation, bioremediation, and adsorption technologies

Pharmaceuticals and hormones presence in effluent of conventional municipal wastewater treatment plants (WWTPs) have been widely reported. Medicinal mushrooms such as Ganoderma species and bentonite clay were recently found to have promising results in wastewater treatment with potential advantages in the removal of pharmaceuticals. Here we investigated a hybrid treatment comprising of three separate processes (no chemicals) i.e., UV irradiation, biological, adsorption (bentonite + dolomite) in a series to enhance the simultaneous removal pharmaceuticals and hormone from wastewaters (real and synthetic). In this study, fungal species Ganoderma lucidum (GLSB) and Ganoderma neo-japonicum (GJSG) are used separately in bioreactors. The work investigated removal efficiencies of four (4) pharmaceuticals and a hormone. The results showed that all investigated pharmaceuticals and hormone were removed in hybrid treatment during 54.5 h treatment. Both GLSB and GJSG reactor series treatments achieved maximum removal in both synthetic and real domestic wastewater. Overall, this study provides promising suggestions for the upgrade and design of WWTPs to simultaneous complete removal of pharmaceuticals and hormone. Present study is a beginning for future development of sustainable tertiary hybrid treatment process in addition to existing WWTPs processes to completely remove the emerging pollutants.

Physical and Chemical Treatability Study in Wastewater Treatment Plant Design (Case Study: Leather Tanning Industry)

The leather tanning industrial is one of the industries that produces wastewater from its production process which contains several contaminants. In wastewater treatment plant design, the treatability study is important because it becomes a consideration in selecting treatment units in wastewater treatment plant based on the characteristics of the wastewater produced. Two methods were carried out in this treatability study, the physical method with imhoff cone sedimentation and the chemical method with jar test. The results of imhoff cone test found that the removal efficiency for wastewater samples was 80% of COD, 72% of BOD, 64.6% of TSS, 72% of total chromium, and 80% of color with the optimum sedimentation time of 50 minutes. Furthermore, the waste water sample was tested by the jar test by adding PAC and FeCl3. The results of the jar test obtained the optimum coagulant dose of 3000 mg/L with PAC coagulant, it was capable of removing 77% of COD, 33% of BOD, 92.68% of TSS, 33% of total chromium, and 98% of color. Based on the results achieved from this study, the physical and chemical treatment can be considered for use in WWTP planning in the leather tanning industry.

Numerical Optimization of Wastewater Treatment Plant Design for a High-Nitrate Industrial Waste

Numerical Optimization of Wastewater Treatment Plant Design for a High-Nitrate Industrial Waste

Process design for removal of pharmaceuticals in wastewater treatment plants based on predicted no effect concentration (PNEC)

Increasing concern on water contamination by micropollutants like pharmaceuticals fuels the development and implementation of technologies to remove micropollutants from municipal wastewater treatment plants (WWTP). However, often the targets and criteria for process design of such technologies are not clarified. This study was conducted to test whether predicted no-effect concentrations (PNEC) can be used as a design parameter for advanced treatment technologies to achieve pharmaceutical levels in WWTP effluents. This goal is consistent with environmental requirements, currently being discussed both by the Danish authorities and the European goals on zero emissions as documented in the draft of the Urban Wastewater Directive. The effluent of a conventional activated sludge WWTP was treated by ozonation and granular activated carbon (GAC) and monitored for 50 pharmaceuticals and iodinated X-ray contrast media, as well as 23 transformation products. Treatment with GAC alone initially achieved concentrations below PNEC for all targeted compounds, but after treating 3,000 – 5,000 bed volumes, the removal for several compounds decreased and the effluent concentrations for clarithromycin and venlafaxine were no longer below PNEC. Ozonation alone effectively reduced the concentrations of most of the compounds with standard ozone dosing of 0.5 mg O3/mg DOC. However, ozonation was unable to remove bicalutamide and oxazepam to reach target concentrations. The operation of both technologies in combination achieved concentrations of all measured pharmaceuticals below the PNEC (even with ozone concentrations of below 0.5 mg O3/mg DOC). Nonetheless, this study suggests that proper steering of WWTP design via the PNEC values alone is obstructed by lack of reliable primal PNEC data and absence of PNEC references for emerging pollutants and potential biologically active transformation products.

Adsorption process modeling to reduce COD by activated carbon for wastewater treatment

Investigations have been carried out on the utilization of Activated Carbon (AC) in adsorption processes for the wastewater treatment of industry and municipal. Sulfides materials, phenols and furfural is a toxic compounds in wastewater from refineries can adversely affect the performance of biological aeration basins in reducing COD levels. This work aims to provide the effectiveness of AC in reducing the COD level of the effluent from the Dissolved Air Flotation (DAF) unit to meet standards of environments protecting and pass the design of wastewater treatment plants. A dynamic adsorption model was developed based on the dispersion of axial in the AC packed bed, assuming that the LDF (linear driving force) model in to the adsorbents is agreed to mass transfer. The model's predictions of chemical oxygen demand breakthrough curve concentrations showed excellent agreement with experimental data. The sensitivity analysis of operational conditions such as flow rate, inlet concentration of COD and bed length was used to gain a better understanding of the optimal design of an AC fixed bed. The results suggest that an AC fixed bed can complement biological treatment of wastewater and address the challenges faced by biological basins in oil refineries.

Physical and Chemical Treatability Assessment for Food Industry Wastewater in Wastewater Treatment Plant Design

Food industry wastewater has characteristics that contain high organic matter and suspended solids. Most of the methods used are physical and chemical treatment because these methods have high efficiency and effectivity. In designing a new wastewater treatment plant, the treatability assessment is essential to any consideration or reference in planning the treatment process to be implemented. This research aims to obtain treatability assessment results that will be used as consideration in planning treatment units in WWTP according to the characteristics of wastewater tested. The removal results of the sedimentation test with Imhoff Cone were able to remove 51.2% COD, 64.04% BOD, and 95.21% TSS with the optimum settling time of 40 minutes. The samples test continued to the rapid-slow mixing test using the jar test, resulting that by adding coagulant at the optimum dose of PAC 120 mg/L, it was capable to remove 68.21% of COD, 73.22% of BOD, and up to 98.07% of TSS at the end of the process. Based on the assessment results, the physical and chemical treatment can remove suspended solids pollutant parameters with high efficiency so it will be considered to be used in planning Wastewater Treatment Plants for this food industry.

What is the best design approach for estimating effluent concentrations from horizontal flow treatment wetlands: the use of volumetric (kV) or areal (kA) removal rate coefficients?

Effluent concentrations from horizontal flow (HF) treatment wetlands can be estimated by using the Tanks-In-Series model for describing hydraulics and first-order removal rate coefficients for describing pollutant removal. In the design of conventional wastewater treatment plants, volumetric removal rate coefficients (kV) are traditionally used in conjunction with the theoretical hydraulic retention time. Areal removal rate coefficients (kA) coupled with the applied areal hydraulic loading rate are widely used in the literature. Despite this, supporting evidence of its appropriateness is scarce in the literature. The objective of this study is to investigate the adequacy of both approaches by analyzing the influence of liquid depth on kV and kA. Data from 74 HF wetlands were collected, covering biochemical oxygen demand and chemical oxygen demand, and diverse types of influents (raw sewage and primary, secondary and tertiary effluents). For these conditions, kV decreased with depth of the wetland system. Regression analyses between depth and removal rate coefficients were performed, and the equations indicated that kV was approximately related to the inverse of depth, while kA was almost independent of depth. These findings endorse the utilization of the areal-based approach for design purposes. The volumetric-based approach can also be used, but the value of kV must be provided together with the depth being considered.

Design and Development of a Low-Cost Wastewater Treatment Plant for the NMCE Campus

Abstract: The characteristics and quantity of wastewater are required to get the correct treatment system for wastewater reuse in the NMCE campus. Water is an essential commodity of society. The water availability in NMCE during the summer season is limited, and the wastewater disposal system in NMCE is not methodical. It is directly discharged into open land; therefore, it must design and develop a wastewater treatment plant for the NMCE campus. Wastewater treatment by constructed wetlands is emerging as the low-cost alternative method involving plant species for sewage treatment. The present study will address the design of a wastewater treatment plant for the NMCE campus.

AWWA Water Science Author Spotlight

Having recently published an article in AWWA Water Science, Rain Richard answered questions from the publication's editor-in-chief, Kenneth L. Mercer, about the research. Pre- and Post-Flushing of Three Schools in Arizona Due to COVID-19 Shutdown Rain Richard and Trevor H. Boyer I currently work at NCS Engineers as a consultant, and my focus is on wastewater treatment design. My goal has always been to bridge the gap between research and industry. I use my research and analytical skills to model treatment plant options for clients and solve issues that occur at wastewater treatment plants, and I am slowly moving into direct potable reuse. Each wastewater treatment plant design for a client is like its own research project. There are so many factors and limitations associated with a design, from policies to budgets. Having patience, thinking outside the box, and presenting the atypical are what make me successful at my job. During the early part of my PhD work, I had been struggling for a week with cross-contamination of my cell cultures, and I couldn’t figure out why. I was really frustrated. The best thing I ever heard was when a professor told me, “Science does not have emotion. Therefore, you should not show it any emotion.” That changed everything for me. A light turned on and I felt like I gained control of my situation again. After that, regardless of how difficult a task was in the lab, I wasn’t bothered by failures or outcomes I wasn’t expecting. It is all a part of science. Rain and her family have just finished a mountain-bike ride in the Phoenix Mountain Preserve. Rain is measuring dissolved oxygen in the various reactors at a wastewater treatment facility. In my opinion, getting direct potable reuse (DPR) to be accepted and practiced in the United States is a major hurdle that we should be implementing right now. The biggest challenge we face will be if we try to implement DPR when it is too little, too late. There are two major areas of resistance that I come across often: public acceptance and cost of implementation, and I think cost outweighs public acceptance. Maybe we aren’t thirsty enough yet, but I really hope we don’t get to that point before we begin to implement DPR. It is an area in which everyone should band together instead of working in silos. Rain takes a leisurely horseback ride at MacDonald's Ranch in Scottsdale, Ariz. I was born in Afghanistan but moved to the United States as a refugee when I was a toddler. Afghanistan is a country that does not have a reliable source of clean water. I think about how fortunate I am to live in such a wonderful country. There are so many opportunities in the United States. Rain is studying a retrofit of a wastewater treatment plant and reading a permit to confirm that the treatment plant can begin construction on a new phase of design. I enjoy the small things. Every night we sit as a family and eat dinner. My kids are active in sports, and I love attending their events. I really enjoy being on the trails near my house. The sunsets are gorgeous, and I enjoy walking my rambunctious dogs. I like to crochet every night before bed to turn my mind off. And of course, I love our family vacations. To learn more about Rain's research, visit the article, available online at https://doi.org/10.1002/aws2.1239.