Communities In Wastewater Treatment Plants Research Articles

DESIGN OF COMMUNAL WASTEWATER TREATMENT PLANT (CASE STUDY IN DEPOK VILLAGE, TRENGGALEK, EAST JAVA)

Planning for a communal scale Wastewater Treatment Plant (WWTP) in Depok Village, Trenggalek Regency, East Java is needed because most of the wastewater in Depok Village is only treated with septic tanks. This study aims to plan a communal scale WWTP design based on the generation of domestic and non-domestic wastewater in Depok Village. The WWTP planning in this study was carried out based on the results of laboratory test parameters for pH, TSS, BOD, COD, total coliform, fatty oil, and ammonia. Based on the test results, it is known that the parameters exceed the required limits according to the Minister of Environment Regulation No. 68 of 2016 is the parameter of TSS, ammonia, and total coliform. The units that are planned are barscreen unit is planned to have a length of 8.65 m, a width of 2.65 m, and a depth of 3 m. The initial settling basin is planned to have a length of 11 m, a width of 3 m, and a depth of 4 m. The anaerobic biofilter unit is planned to have a length of 15 m, a width of 7.5 m, and a depth of 2.5 m. The aerobic biofilter unit is planned to have a length of 16.5 m, a width of 8.5 m, and a depth of 2 m. The final settling basin is planned to have a length of 37 m, a width of 18.5 m and a depth of 2.5 m. The control body is planned to have a length of 9.5 m, a width of 5 m and a depth of 2 m. Meanwhile, disinfection is planned using a disinfectant pump.

The feasibility of SARS-CoV-2 surveillance using wastewater and environmental sampling in Indonesia.

Wastewater-based epidemiology (WBE) surveillance as an early warning system (EWS) for monitoring community transmission of SARS-CoV-2 in low- and middle-income country (LMIC) settings, where diagnostic testing capacity is limited, needs further exploration. We explored the feasibility to conduct a WBE surveillance in Indonesia, one of the global epicenters of the COVID-19 pandemic in the middle of 2021, with the fourth largest population in the world where sewer and non-sewered sewage systems are implemented. The feasibility and resource capacity to collect samples on a weekly or fortnightly basis with grab and/or passive sampling methods, as well as to conduct qualitative and quantitative identification of SARS-CoV-2 ribonucleic acid (RNA) using real-time RT-PCR (RT-qPCR) testing of environmental samples were explored. We initiated a routine surveillance of wastewater and environmental sampling at three predetermined districts in Special Region of Yogyakarta Province. Water samples were collected from central and community wastewater treatment plants (WWTPs), including manholes flowing to the central WWTP, and additional soil samples were collected for the near source tracking (NST) locations (i.e., public spaces where people congregate). We began collecting samples in the Delta wave of the COVID-19 pandemic in Indonesia in July 2021. From a 10-week period, 54% (296/544) of wastewater and environmental samples were positive for SARS-CoV-2 RNA. The sample positivity rate decreased in proportion with the reported incidence of COVID-19 clinical cases in the community. The highest positivity rate of 77% in week 1, was obtained for samples collected in July 2021 and decreased to 25% in week 10 by the end of September 2021. A WBE surveillance system for SARS-CoV-2 in Indonesia is feasible to monitor the community burden of infections. Future studies testing the potential of WBE and EWS for signaling early outbreaks of SARS-CoV-2 transmissions in this setting are required.

Communal Wastewater Treatment Plants’ Effectiveness, Management, and Quality of Groundwater: A Case Study in Indonesia

The Special Region of Yogyakarta is one of the provinces in Indonesia with a large number of communal wastewater treatment plants (CWWTPs). However, less than 40% of CWWTPS in the province are able to be operated well. This study aims to determine the effectiveness of CWWTPs concerning the quality of the surrounding groundwater. The research location was in Mlati, one of three sub-districts with the highest number of CWWTPs and highest population density in the province. Technical data were analyzed in a laboratory, including water quality of CWWTPs and groundwater quality. This study also analyzed non-technical data related to CWWTP management. These data were collected through in-depth interviews with CWWTP managers and users. The data were analyzed systematically, not only quantitatively but qualitatively. The distribution of water quality from CWWTP treatment and groundwater was mapped using inverse distance weighting (IDW). The results show that the CWWTP effluent meets quality standards for pH, temperature, COD, oil and grease, and ammonia. However, some CWWTPs fail to meet the quality standards for the TSS and E. coli parameters. Groundwater has an acidic pH, with ammonia, nitrite, and zinc parameters meeting quality standards, but oil and grease, COD, nitrate, and Pb concentrations exceed quality standards in several wells. This study indicates that the presence of CWWTPs is not correlated with the quality of groundwater due to the inefficiency of the CWWTPs, the unmet coverage area, and the conditions of sanitation facilities at the location.

Ciliate Communities Respond via Their Traits to a Wastewater Treatment Plant With a Combined UASB–Activated Sludge System

Assessing functional diversity of communities is an efficient method to link community composition to ecosystem quality. Still, studies using functional traits of microeukaryote ciliate communities in biological wastewater treatment plants are lacking. The present work explores the functional diversity of the ciliate protist community in a wastewater treatment plant (WWTP) operating with a combined UASB-activated sludge system, and specifically to: 1) investigate the taxonomic and functional composition of the ciliate communities over time; 2) compare taxonomic and functional diversity indices with regard to its applicability in WWPS; 3) assess the relationship between the ciliate community’s functional composition and the WWTPs temporal conditions; and 4) investigate the potential use of functional diversity as an indicator of WWTP efficiency. Totally, we recorded 21 ciliate species throughout 37 samplings. The number of species was low compared to other plants. Bacterivorous and flake-forming species were the main functional strategies found in the samples. The correlation between taxonomic and functional richness was significant, indicating a functionally redundant community. There was a correlation between the Simpson and Rao’s quadratic entropy indexes suggesting that loss of taxonomic diversity leads to a loss of functional diversity. The homogeneity of the measured physical and chemical data led to functional homogenization and redundancy (homogenous CWM) of the ciliate community. The functional diversity is positively correlated with parameters of removal efficiency, indicating a promising application in WWTPs. Future studies will broaden knowledge on functional diversity in biological wastewater treatment systems, this being a first step with the unprecedented application of this methodology in artificial ecosystems.

Temperature mediated the balance between stochastic and deterministic processes and reoccurrence of microbial community during treating aniline wastewater

Seasonal temperature changes significantly affect microbial community diversity, composition, and performance in wastewater treatment plants. However, the community assembly mechanisms under seasonal temperature variations remain unclear. Here, we carried out temperature cycling experiments (30 °C, 35 °C, 37 °C, 40 °C, 42 °C, 45 °C, 40 °C, and 30 °C) to investigate how temperature impacts microbial performance and co-occurrence network and how assembly processes determine the structure and function of microbial communities during treating aniline wastewater. During the 195-day operation, the system achieved an efficient and stable aniline removal of 99%. Interestingly, α-diversity and network complexity were negatively correlated with temperature but could be recovered when the temperature was returned to 30 °C. The results showed that functional redundancy was probably responsible for the excellent microbial performance during the whole process. Null model analyses presented that deterministic process dominated the community when the temperature was 30 °C, and stochasticity dominated the assembly process when the temperature was over 30 °C. Overall, the balance between stochastic and deterministic processes in the treatment of aniline wastewater mediated the reoccurrence of microbial community and co-occurrence network at different temperatures. This study provides new insights into microbial community reoccurrence under seasonal temperature changes and a theoretical basis for regulating microbial communities in wastewater treatment plants.

Real-Time Implementation of Wastewater Monitoring System on the Communal Wastewater Treatment Plant using the IoT Technology

A Wastewater Treatment Plant (WWTP) is a plant used to reduce the pollutants contained in the wastewater. The optimal operation of the WWTP can be achieved when the performance of WWTP is monitored regularly. This paper presents an actual implementation of the wastewater monitoring system on the communal WWTP using the Internet of Things (IoT) technology. The proposed method employs the sensors and electronic modules available in the market and the popular ThingSpeak IoT platform. Four sensors, namely pH, temperature, turbidity, and Dissolved Oxygen (DO), monitor the wastewater’s parameters. The IoT hardware on the field communicates with the ThingSpeak cloud server using a GSM modem. The proposed monitoring system has been implemented on the Tirtarona WWTP, a communal WWTP located in Malang, Indonesia. The preliminary evaluation results show that the proposed method works properly and achieves the goal of the real-time wastewater monitoring system. Further, the solar panel is installed at the top of the sensor module for providing a self-powered and green energy monitoring system.

Characterization of Microbial Communities in Wastewater Treatment Plants Containing Heavy Metals Located in Chemical Industrial Zones.

Water pollution caused by heavy metals (HMs) poses a serious risk to human health and the environment and can increase the risk of diabetes, cancer, and hypertension in particular. In this study, two full-scale wastewater treatment plants (WWTPs) in industrial zones in southern China were selected to analyze the microbial community structure, diversity, similarity, and differentiation in the anoxic/oxic (AO) and anoxic/oxic membrane bioreactor (AO-MBR) units under the stress of HMs. High-throughput sequencing showed that microbial diversity and abundance were higher in the AO process than in the AO-MBR process. In the two WWTPs, the common dominant phyla were Proteobacteria and Bacteroidetes, while the common dominant genera were Gemmatimonadaceae, Anaerolineaceae, Saprospiraceae, and Terrimonas. Manganese (Mn) and zinc (Zn) positively correlated with Saccharimonadales, Nakamurella, Micrococcales, and Microtrichales, whereas copper (Cu) and iron (Fe) positively correlated with Longilinea and Ferruginibacter. Additionally, the relative abundances of Chloroflexi, Patescibacteria, and Firmicutes differed significantly (p < 0.05) between the two processes. These results may provide comprehensive outlooks on the characterization of microbial communities in WWTPs, which could also help to reduce the potential environmental risks of the effluent from WWTPs located in industrial zones.

Non-technical dimensions of communal wastewater treatment plant sustainability in peri-urban Yogyakarta, Indonesia

Background: This study focuses on identifying non-technical aspects that influence the sustainability of communal wastewater treatment plants (WWTPs) in a peri-urban area of Indonesia. Methods: A questionnaire survey was conducted by random sampling using a method of descriptive analysis that combines qualitative and quantitative approaches. Economic support for communal WWTPs was measured by the community’s Willingness to Pay (WTP) and Ability to Pay (ATP). Results: The results indicate that social dimension, such as a community’s level of participation are critically important in sustaining communal WWTPs. In addition, institutional dimension influences the degree of satisfaction a community has toward the WWTP management. This support is reinforced by social capital in the form of a philosophy of mutual cooperation, like gotong royong (cooperation by members of a community to achieve a common goal) and swadaya (self-reliance). Conclusions: The findings of this study can be used in Indonesia to make policy recommendations for managing and ensuring sustainability of communal WWTPs on a non-technical dimension. Additionally, gotong royong deserves to be promoted internationally as a fundamental value for fostering participation and contribution.

Public Awareness of and Support for the Use of Wastewater for SARS-CoV-2 Monitoring: A Community Survey in Louisville, Kentucky.

The majority of sewer systems in the United States and other countries are operated by public utilities. In the absence of any regulation, the public perception of wastewater monitoring for population health biomarkers is an important consideration for a public utility commission when allocating resources for this purpose. We conducted a survey in August 2021 as part of an ongoing COVID-19 community prevalence study in Louisville/Jefferson County, KY, US. The survey comprised seven questions about wastewater awareness and privacy concerns and was sent to approximately 35 000 households randomly distributed within the county. A total of 1220 adults were involved in the probability sample, and data from 981 respondents were used in the analysis. A total of 2444 adults additionally responded to the convenience sample, and data from 1751 respondents were used in the analysis. The samples were weighted to obtain estimates representative of all adults in the county. Public awareness of tracking the virus that causes COVID-19 in sewers was low. Opinions strongly support the public disclosure of monitoring results. Responses showed that people more strongly supported measurements in the largest areas (>50 000 households), typically representing population levels found in a large community wastewater treatment plant. Those with a history of COVID-19 infection were more likely to support highly localized monitoring. Understanding wastewater surveillance strategies and privacy concern thresholds requires an in-depth and comprehensive analysis of public opinion for continued success and effective public health monitoring.

MiDAS 4: A global catalogue of full-length 16S rRNA gene sequences and taxonomy for studies of bacterial communities in wastewater treatment plants

Microbial communities are responsible for biological wastewater treatment, but our knowledge of their diversity and function is still poor. Here, we sequence more than 5 million high-quality, full-length 16S rRNA gene sequences from 740 wastewater treatment plants (WWTPs) across the world and use the sequences to construct the ‘MiDAS 4’ database. MiDAS 4 is an amplicon sequence variant resolved, full-length 16S rRNA gene reference database with a comprehensive taxonomy from domain to species level for all sequences. We use an independent dataset (269 WWTPs) to show that MiDAS 4, compared to commonly used universal reference databases, provides a better coverage for WWTP bacteria and an improved rate of genus and species level classification. Taking advantage of MiDAS 4, we carry out an amplicon-based, global-scale microbial community profiling of activated sludge plants using two common sets of primers targeting regions of the 16S rRNA gene, revealing how environmental conditions and biogeography shape the activated sludge microbiota. We also identify core and conditionally rare or abundant taxa, encompassing 966 genera and 1530 species that represent approximately 80% and 50% of the accumulated read abundance, respectively. Finally, we show that for well-studied functional guilds, such as nitrifiers or polyphosphate-accumulating organisms, the same genera are prevalent worldwide, with only a few abundant species in each genus.

The structure of microbial communities of activated sludge of large-scale wastewater treatment plants in the city of Moscow

Microbial communities in wastewater treatment plants (WWTPs) play a key role in water purification. Microbial communities of activated sludge (AS) vary extensively based on plant operating technology, influent characteristics and WWTP capacity. In this study we performed 16S rRNA gene profiling of AS at nine large-scale WWTPs responsible for the treatment of municipal sewage from the city of Moscow, Russia. Two plants employed conventional aerobic process, one plant—nitrification/denitrification technology, and six plants were operated with the University of Cape Town (UCT) anaerobic/anoxic/oxic process. Microbial communities were impacted by the technology and dominated by the Proteobacteria, Bacteroidota and Actinobacteriota. WWTPs employing the UCT process enabled efficient removal of not only organic matter, but also nitrogen and phosphorus, consistently with the high content of ammonia-oxidizing Nitrosomonas sp. and phosphate-accumulating bacteria. The latter group was represented by Candidatus Accumulibacter, Tetrasphaera sp. and denitrifiers. Co-occurrence network analysis provided information on key hub microorganisms in AS, which may be targeted for manipulating the AS stability and performance. Comparison of AS communities from WWTPs in Moscow and worldwide revealed that Moscow samples clustered together indicating that influent characteristics, related to social, cultural and environmental factors, could be more important than a plant operating technology.

First Demonstration of Nitrate Reduction Using Woodchip Bioreactor Technology at a Small Community Wastewater Treatment Plant

Eutrophication can be accelerated by excess amounts of reactive Nitrogen (Nr) entering aquatic ecosystems. Historically, the circa 1960 Bolton Wastewater Treatment Plant, Warren County, New York (USA), discharged plant effluent for final polishing to natural sand infiltration beds, which entered the groundwater and then tributaries to Lake George. The absence of a denitrification unit process at the Bolton facility resulted in the construction of a woodchip bioreactor and a corresponding demonstration project to evaluate denitrification of plant effluent prior to sand bed discharge. This Denitrifying Bioreactor (DNBR) installation was the first real time, in-situ application of this “green technology” for a small wastewater treatment plant world-wide. The Bolton DNBR reduced nitrate-nitrogen concentrations in the tertiary effluent by 38% when compared with untreated tertiary effluent. Here we show that wastewater denitrification using this passive, environmentally compatible technology offers a low-cost, effective tool for small community wastewater treatment plants where excess Nr is problematic. Combined with diligent plant operator attention, this innovative treatment should move beyond concept into full scale field applications for other small community wastewater treatment plants globally, using lessons learned at the Bolton facility.

Blue Water Footprint and Grey Water Footprint Assessment of Block-Printed Batik-Making Process Coloured by Indigo (Indigofera sp.), Tingi (Ceriops sp.) and Mahogany (Swietenia sp.) Dyes

The Indonesian batik, which is usually produced by small and medium enterprises (SMEs) often consumes a lot of water and causing environmental pollution. Therefore, a study to map the water use for batik production is required. This study examines the Blue Water Footprint (BWF) and Grey Water Footprint (GWF) of block-printed batik making-process coloured by Indigo (Indigofera sp.), Mahogany (Swietenia sp.) and Tingi (Ceriops sp.) dyes produced by a batik SME in Jarum village of Klaten Regency, Indonesia. The average BWF of block-printed batik making-process coloured by natural dyes was lower than the GWF and Indigo consumes more water in dyeing, followed by Tingi and Mahogany. The dyeing process consumes less water for BWF (2.96 L/pc), while the biggest portion of BWF was contributed from the wax removal process (152.81 L/pc). Implementation of cleaner production by managing the grey water, such as the implementation of communal Wastewater Treatment Plant, adopting water conservation strategies and educating the craftsmen are necessary to achieve batik and water resource sustainability.

Evaluation of Post-Construction Communal Wastewater Treatment Plants (WWTPs) in Sleman District, Special Region of Yogyakarta

The Special Region of Yogyakarta Government took one step to improve access to proper sanitation for the community through the Communal WWTP. There are four communal WWTP procurement programs in Sleman District: Community-based Sanitation, Urban Sanitation Rural Infrastructure (USRI), Special Allocation Fund and Community-based Environmental Sanitation. After the Communal WWTP was built and operated, various problems indicate the Communal WWTP has not run optimally after construction. Therefore, this study evaluated thirteen Communal WWTPs in Sleman District after construction was carried out. The aspects reviewed in this study were the administrator institutional and the management’s performance using the scoring method. The evaluation results based on the administrator institutional aspect and the management’s performance showed that Ambarketawang WWTP had less performance with a total score of 16. At the same time, other WWTPs got the optimal category with a total score more than equal to 25. These results indicate that the Community-Based Environmental Sanitation procurement program was considered less than optimal because the Ambarketawang WWTP did not keep Communal WWTP documentation and had no maintenance Standard Operational Procedure (SOP). The administrators did not also understand the main tasks and functions as administrators.

Meta-analysis of Microbial Communities in the Activated Sludge of Wastewater Treatment Plants Under Different Climate Types

Microbial communities in wastewater treatment plants(WWTPs) are very important for water purification in the context of public drinking water safety and environmental health. Therefore, it is necessary to explore the trends in microbial community structure and diversity in sewage treatment plants and their main environmental impact factors under different climates in China. Based on high-throughput sequencing techniques, a meta-analysis was conducted to screen the 16S rRNA genes in an open database. We analyzed the trends in microbial community structure and diversity in WWTPs under three climate types(Dwa, Cfa, and Cwa) in China. We then constructed cohesion models to examine the core microbial taxa and their interactions within the communities. We also used a piecewise structural equation model(PSEM) to examine the effects of different climate types on microbial community structure. The three climate types significantly affected the structure and diversity of the microbial communities, with patterns correlated with influent pH, mixed liquid temperature, conductivity, and nitrogen concentrations(P<0.05). Based on the PSEM analysis, the β-diversity of the microbial communities was directly correlated with latitude, while α-diversity was indirectly correlated with latitude through conductivity and water temperature. Based on the cohesion modeling, microbial community stability was the highest under Dwa climate followed by the Cfa climate. This could be explained by a small subset of highly connected taxa capable of withstanding disturbance, indicating an important stability role. In contrast, the stability of the microbial communities under the Cwa climate was low, and no species with strong negative cohesion were observed. Overall, the structure, diversity, and stability of microbial community in WWTPs were found to be sensitive to climate, and the responsive mechanisms of α-diversity and β-diversity with respect to latitude were distinct.

Short-term exposure to benzalkonium chloride in bacteria from activated sludge alters the community diversity and the antibiotic resistance profile.

The continuous introduction of cleaning products containing benzalkonium chloride (BAC) from household discharges can mold the microbial communities in wastewater treatment plants (WWTPs) in a way still poorly understood. In this study, we performed an in vitro exposure of activated sludge from a WWTP in Costa Rica to BAC, quantified the changes in intI1, sul2, and qacE/qacEΔ1 gene profiles, and determined alterations in the bacterial community composition. The analysis of the qPCR data revealed elevated charges of antibiotic resistance genes in the microbial community; after BAC's exposure, a significant increase in the qacE/qacEΔ1 gene, which is related to ammonium quaternary resistance, was observed. The 16S rRNA gene sequences' analysis showed pronounced variations in the structure of the bacterial communities, including reduction of the alpha diversity values and an increase of the relative abundance of Alphaproteobacteria, particularly of Rhodospseudomonas and Rhodobacter. We confirmed that the microbial communities presented high resilience to BAC at the mg/mL concentration, probably due to constant exposure to this pollutant. They also presented antibiotic resistance-related genes with similar mechanisms to tolerate this substance. These mechanisms should be explored more thoroughly, especially in the context of high use of disinfectant.

Revealing the dissimilar structure of microbial communities in different WWTPs that treat fish-canning wastewater with different NaCl content

Studies that characterize the microbial communities in wastewater treatment plants (WWTPs) are numerous, yet similar studies in industrial WWTPs treating fish-canning effluents are limited. The microbial communities in samples of 4 fish-canning WWTPs that operated under different NaCl concentrations were investigated by qPCR and partial 16S rRNA gene Illumina sequencing. The absolute abundances of key microbial populations (Total Bacteria, Archaea and Fungi, ammonium oxidizing bacteria (AOB), Mycolata, Candidatus Microthrix, Ca. Accumulibacter and Ca. Competibacter) presented statistical differences among the WWTPs. The NaCl concentration negatively affected the absolute abundance of Bacteria and Fungi, filamentous, and phosphate (PAO) and glycogen (GAO) accumulating bacteria, while AOB and Ca. Microthrix populations were statistically higher in the WWTP with higher NaCl contents. On the other hand, the main bacterial operational taxonomic units (OTUs) were classified as members of Kouleothrix (Chloroflexia, Chloroflexi) and Tetrasphaera (Actinomycetia, Actinobacteria), family Beijerinckiaceae (Alphaproteobacteria, Proteobacteria), order Betaproteobacteriales (Gammaproteobacteria, Proteobacteria), Sphingobacteriales (Sphingobacteriia, Bacteroidetes) and Frankiales (Actinobacteria, Actinobacteria), class Anaerolineae (Chloroflexi), phylum Chloroflexi and Bacteria_unclassified. The structure of the bacterial community was highly dissimilar among the 4 WWTPs, as the identities of the dominant OTUs differed significantly among them. Therefore, the individual characteristics of the different WWTPs, mainly NaCl concentration, were responsible for the narrow assemblage of the bacterial communities. Different OTUs belonging to the phyla Actinobacteria, Bacteroidetes, Chloroflexi, Gemmatimonadetes and Proteobacteria were revealed as salt-tolerant. Taking into account these results, NaCl content was an important driver of the abundance of microbial populations and the bacterial community structure in the analysed industrial facilities.

Analisis Kebijakan Sistem Pengolahan Air Limbah Rumah Tangga Kota Depok

Study on domestic wastewater management policies is still minimal. Previous research was based on law. This research was conducted to discuss according hierarchy of regulations, then policy analysis under the stakeholders’ understanding. Wastewater management is important because it involves human health and the availability of clean water. The problem in Depok City is untreated domestic wastewater polluting rivers. This condition is caused by the communal Waste Water Treatment Plant (WWTP) that has not been able to reach all settlements and housing. The study aims to conduct a policy analysis of domestic wastewater management to reduce household pollution in Depok. The study was conducted in 2018. Primary data were consisting of perceptions of domestic waste policy makers at regional to national level. Secondary data were previous studies and policy products of Depok City. Qualitative research is determined by the results of content analysis and stakeholder analysis. Primary data obtained through interviews and focus group discussion. The finding is domestic wastewater pollution comes from settlements established before 2012 and settlements that are not served by integrated communal WWTP in Depok City. These conditions can be overcome by building inexpensive and easy to operate domestic wastewater treatment system. The research recommendation is the application of a constructed wetland. The policy implication is adoption of WWTP system in Depok City regulations.

Mass-immigration determines the assembly of activated sludge microbial communities

The assembly of bacterial communities in wastewater treatment plants (WWTPs) is affected by immigration via wastewater streams, but the impact and extent of bacterial immigrants are still unknown. Here, we quantify the effect of immigration at the species level in 11 Danish full-scale activated sludge (AS) plants. All plants have different source communities but have very similar process design, defining the same overall environmental growth conditions. The AS community composition in each plant was strongly reflected by the corresponding influent wastewater (IWW) microbial composition. Most species in AS across the plants were detected and quantified in the corresponding IWW, allowing us to identify their fate in the AS: growing, disappearing, or surviving. Most of the abundant species in IWW disappeared in AS, so their presence in the AS biomass was only due to continuous mass-immigration. In AS, most of the abundant growing species were present in the IWW at very low abundances. We predicted the AS species abundances from their abundance in IWW by using a partial least square regression model. Some species in AS were predicted by their own abundance in IWW, while others by multiple species abundances. Detailed analyses of functional guilds revealed different prediction patterns for different species. We show, in contrast to the present understanding, that the AS microbial communities were strongly controlled by the IWW source community and could be quantitatively predicted by taking into account immigration. This highlights a need to revise the way we understand, design, and manage the microbial communities in WWTPs.

Inhibition of the activated sludge-associated enzyme phosphatase by transition metal oxyanions.

Organic esters of phosphoric acid and other organophosphorous compounds are enzymatically hydrolyzed during wastewater treatment by microbial phosphoesterases, especially by phosphomonoesterase (phosphatase). For physiological reasons, the enzyme is inhibited by its main inorganic reaction product, ortho-phosphate. It is known that oxyanions of transition metals, resembling the molecular topology of ortho-phosphate, e.g. vanadate and tungstate, are more potent inhibitors for microbial alkaline phosphatase than phosphate. To proof this effect for activated sludge, a multitude of samples from a communal wastewater treatment plant was exposed at pH values from 7.00 to 8.50 to tungstate, vanadate, and molybdate. Inhibition effects were determined by a sensitive fluorimetric microplate assay and characteristic parameters (IC50 and IC20 concentrations) were deduced from modelled dose-response functions. Mean inhibitor concentrations (in brackets: ranges) causing 50% inactivation (IC50) at pH 7.50 were 2.5 (1.3-4.1) μM tungstate, 2.9 (1.6-5.5) μM vanadate, and 41.4 (33.6-56.7) μM molybdate. Vanadate and tungstate concentrations between 0.6 and 0.7 μM provoked a 20% (IC20) inhibition. The inhibition efficiency of tungstate and molybdate decreased with increasing pH, whereas vanadate reacted pH independently. These results underline the necessity to consider enzyme inhibition assessing the limitations and potentials of biological wastewater treatment processes.