Operation Of Wastewater Treatment Plants Research Articles

Recovery of extracellular biopolymers from conventional activated sludge: Potential, characteristics and limitation

Extracellular polymeric substances (EPS) are biopolymers that can be recovered from excess sludge, which could contribute to a more sustainable wastewater treatment plant (WWTP) operation. An example is alginate like extracellular polymers (ALE) contained in the biopolymers could be a potential resource with a highly-added value. EPS extraction for ALE from aerobic granules sludge (AGS) has already been well studied and applied in the Netherlands. On the other hand, there is little attention to the recovery of biopolymers from conventional activated sludge (CAS). In this study, flocculent sludge from eight CAS-WWTPs in China was collected and their EPS/biopolymers were extracted to investigate their recovery potential, chemical & physical properties and limiting factors. The results revealed that the biopolymers extracted and purified from CAS ranged from 90 to 190 mg/g VSS. The compositional characteristics of the biopolymers were observed by FT-IR, 3D-EEM and UV-Visible spectra, demonstrating some differences in the composition and property of the biopolymers from the different WWTPs. The biopolymers had a similarity of about 60% to a commercial alginate with respect to chemical functional groups and the alginate equivalent was >400 mg/g biopolymers. Moreover, the biopolymers consisted of poly (guluronic acid) blocks (20%-30%) and poly (guluronic acid-mannuronic acid) blocks (8%-28%), and the ionic hydrogel formation tests indicated that condensed beads were immediately formed once the drops of the biopolymers came in contact with CaCl2 solution. These results demonstrated that the biopolymers extracted had a relatively high gel-forming capacity and might also have a potential application as commercial biopolymers. Furthermore, the factors influencing the biopolymers’ formation such as influent substrate, nutrient content and microbial community and the related mechanisms were investigated. Among them, increasing soluble organics (SCOD) content and low nutrient content (C/N/P) in the influent could promote the biopolymers’ formation. Also, different bacteria in BNR processes might have positive or negative effects on the biopolymers’ formation. In conclusion, the diversity and abundance of bacteria were identified to be a crucial and decisive factor controlling biopolymers’ extraction and composition.

Prediction of biogas production in anaerobic co-digestion of organic wastes using deep learning models

Interest in anaerobic co-digestion (AcoD) has increased significantly in recent decades owing to enhanced biogas productivity due to the utilization of different organic wastes, such as food waste and sewage sludge. In this study, a robust AcoD model for biogas prediction is developed using deep learning (DL). We propose a hybrid DL architecture, i.e., DA–LSTM–VSN, wherein a dual-stage-attention (DA)-based long short-term memory (LSTM) network is integrated with variable selection networks (VSNs). To enhance the model predictability, we perform hyperparameter optimization. The model accuracy is validated using long-term AcoD monitoring data measured over two years of municipal wastewater treatment plant operation and then compared with those of two other DL-based models (i.e., DA–LSTM and the standard LSTM). In addition, the feature importance (FI) is analyzed to investigate the relative contribution of input variables to biogas production prediction. Finally, we demonstrate the successful application of the validated DL model to the AcoD process optimization. Results show that the model accuracy improved significantly by incorporating DA into LSTM, i.e., the coefficient of determination (R2) increased from 0.38 to 0.68; however, the R2 can be further increased to 0.76 by combining DA–LSTM with a VSN. For the biogas prediction of the AcoD model, the VSN contributes significantly by employing the discontinuous time series of measurement data on biodegradable organic-associated variables during AcoD. In addition, the VSN allows the AcoD model to be interpretable via FI analysis using its weighted input features. The FI results show that the relative importance is vital to variables associated with food waste leachate, whereas it is marginal for those associated with the primary and chemically assisted sedimentation sludges. In conclusion, the AcoD model proposed herein can be utilized in practical applications as a robust tool because it can provide the optimal sludge conditions to improve biogas production. This is because it facilitates the time-series biogas prediction at the full scale using unprocessed datasets with either missing value imputation or outlier removal.

Optimizing Power Reclamation of Micro Hydro Turbines in WWTPs Aeration Basins

Abstract This study investigates the optimum operating conditions and design configurations that can optimize the power reclaimed by small hydro turbines derived by the rising water-bubble current. The rising current is generated by the compressed air introduced by the diffusers at the bottom of aeration basins of Wastewater Treatment Plants (WWTPs). While optimizing the power production, the standard oxygen transfer efficiency (SOTE) is monitored since it is a significant parameter that cannot be sacrificed in the operation of WWTPs. Using one set of turbine blades, it was found out that the highest velocity is obtained in the upper half of the water column (70% - 80%). In contrast, the lowest velocities were obtained just above the air diffuser and at the water surface. Testing started with using a single turbine (ST) to determine the location of the optimum power reclaimed at each tested airflow (1.18, 1.42, 1.65, and 1.89 L/s). Then using double turbine (DT) and triple turbine (TT) to compare their performance to the ST’s maximum power increased power reclamation. The maximum percentage of increase in power reclamation for DT is 19.59%, while it is 20.24% in the case of TT. At a commonly used airflow in WWTPs (1.42 L/s), the optimum configurations of DTs and TTs were selected to investigate the effect of having the proposed setup on the SOTE. For membrane diffusers, DTs and TTs limited the dispersion of the air bubbles in the tank, therefore, reducing the SOTE (8.3% for DT and 3.7% for the TT). The ceramic and sharp-nub diffusers were also tested versus rubber membrane ones to determine the effect of using the ceramic and sharp-nub diffusers on the power reclamation and SOTE. Ceramic diffusers neither achieve higher power reclamation than the membrane nor increases the SOTE. In contrast, sharp-nub diffusers increase the SOTE for all configurations compared to membranes, but this came into account of power reclamation, where sharp-nub diffusers cause a DT and a TT to produce less power than ST does.

Phosphorus recycling from activated sludge of full-scale wastewater treatment plants by fast inversion of the biological phosphorus elimination mechanism

Enhanced biological phosphorus removal (EBPR) is often applied by wastewater treatment plants (WWTPs) whereby phosphorus (P) is accumulated in the activated sludge (AS) biomass. The German Sewage Sludge Ordinance demands that large WWTPs recycle P from their process streams by 2029. This study aimed at evaluating the potential of an acetate-mediated P re-dissolution from non-acclimated AS of three full-scale WWTPs. All AS exhibited enhanced P re-dissolution during acetate uptake and followed kinetics typical of EBPR systems. Re-dissolution efficiency differed depending on the WWTP operation mode. The highest P re-dissolution yield (56% of total P) was obtained for pure EBPR sludge. Lower re-dissolution rates of 19–22% were observed in the AS from WWTPs that employed additional chemical P removal, probably due to shortage of intracellular polyphosphate. Pure EBPR systems may be suited for the implementation of a re-dissolution based strategy for P recycling from AS where P depleted AS could potentially be returned to the biological treatment stage.

Sorption of Heavy Metals by Sewage Sludge and Its Mixtures with Soil from Wastewater Treatment Plants Operating in MBR and INR Technology.

Sewage sludge is a very complex system, with solids and water. It is generated as waste from wastewater treatment. Sewage sludge is used to fertilize agricultural and forest areas and to rehabilitate devastated areas. It is a good organic fertilizer because it contains significant amounts of nutrients beneficial for plant development and humus-forming substances. The composition of sludge from municipal wastewater treatment plants is similar to soil organic matter, therefore it can be used to improve the physicochemical properties of soil, increasing its sorption capacity. Research material was collected in the Swietokrzyskie and Mazowieckie Voivodships. Sewage sludge was collected from the wastewater treatment plants in Sitkowka Nowiny (Sitkowka) and Kunow, as well as high-quality agricultural soil from Opatowiec and sandy-clay soil from Jastrzebie. Research was carried out on the sorption of heavy metals (Cd, Cr, Cu, Pb, Ni, Zn) by mixtures of sewage sludge with soil. The calculations were made for the concentrations of heavy metals in sewage sludge, soil, and sewage sludge–soil mixtures. The geoaccumulation index (Igeo) and the risk assessment code (RAC) were calculated. Increased sorption capacity was demonstrated in samples with a predominance of sewage sludge. It was shown that heavy metals from sewage sludge, after mixing with soil, changed their form from immobile to mobile.

Performance evaluation of wastewater treatment plants under the sewage variations imposed by COVID-19 spread prevention actions.

Coronavirus disease 2019 (COVID-19) and its spread prevention actions (SPAs) have affected a large number of human activities globally in 2020-2021. Temporary lockdowns, stay-at-home policies, movement restrictions, and personal health care actions have relatively changed the daily life routine in urban areas which can eventually affect the characteristics of municipal wastewater (MW). This study evaluates the performance of wastewater treatment plants (WWTPs) during COVID-19 pandemic and related SPAs. This evaluation also considers MW variations in quality and quantity and compares the performance of WWTPs (2020) with earlier data (2015–2019). For this purpose, 23 WWTPs located in Isfahan province, Iran, were chosen as the study area and classified based on their locations, biological treatment unit, and capacities. Results indicate that the inflow of WWTPs increased 20 % on average during SPAs, while the concentrations of COD and BOD in MW decreased 23 and 16 %, respectively. Nevertheless, the performance of WWTPs remained rather constant. It is concluded that increasing the dilute domestic proportion of MW, particularly in smaller communities, as a matter of COVID-19 SPAs could not impose adverse impacts on wastewater treatment operations and pollution removal. Different types of secondary treatment units, such as activated sludge, stabilization pond, and aerated lagoon showed stable performances. However, disinfection was enhanced in WWTPs in order to reduce the probability of viral transmission via wastewater for reuse. This study also recommends that the characteristics of MW, and not treated wastewater, can be used as an indicator for coordinating SPAs in similar epidemics. This notification can be helpful for the management of WWTPs and risk control in urban areas.

Data Driven Detection of Different Dissolved Oxygen Sensor Faults for Improving Operation of the WWTP Control System

Sensor faults frequently occur in wastewater treatment plant (WWTP) operation, leading to incomplete monitoring or poor control of the plant. Reliable operation of the WWTP considerably depends on the aeration control system, which is essentially assisted by the dissolved oxygen (DO) sensor. Results on the detection of different DO sensor faults, such as bias, drift, wrong gain, loss of accuracy, fixed value, or complete failure, were investigated based on Principal Components Analysis (PCA). The PCA was considered together with two statistical approaches, i.e., the Hotelling’s T2 and the Squared Prediction Error (SPE). Data used in the study were generated using the previously calibrated first-principle Activated Sludge Model no.1 for the Anaerobic-Anoxic-Oxic (A2O) reactors configuration. The equation-based model was complemented with control loops for DO concentration control in the aerobic reactor and nitrates concentration control in the anoxic reactor. The PCA data-driven model was successfully used for the detection of the six investigated DO sensor faults. The statistical detection approaches were compared in terms of promptness, effectiveness, and accuracy. The obtained results revealed the way faults originating from DO sensor malfunction can be detected and the efficiency of the detection approaches for the automatically controlled WWTP.

Synergistic partial denitrification, anammox and in-situ fermentation (SPDAF) process for treating domestic and nitrate wastewater: Response of nitrogen removal performance to decreasing temperature

A synergistic partial denitrification, anaerobic ammonium oxidation (Anammox), and in-situ fermentation (SPDAF) system was established to solve problems of wastewater treatment plants (WWTPs) in combined treatment of domestic sewage, and nitrate wastewater discharged from industrial areas. The SPDAF system was started up at decreasing temperatures (26.8–18.9 ℃), and remained robust at abrupt temperature drop and drastic temperature fluctuations (20.7–14.1 ℃). The influent and effluent total inorganic nitrogen (TIN) were 97.0 ± 3.7 mg/L and 10.3 ± 4.0 mg/L, respectively. In-situ fermentation supplemented electron donors for NO3–-N reduction. A high TIN removal efficiency, of 89.5 ± 3.9% was obtained. Specifically, Anammox contributed 90.9 ± 5.2% to TIN removal. Furthermore, the abundances of hydrolysis and acidogenesis bacteria were 14.02% and 29.47% in the low and high zones, respectively, which promoted fermentation and the use of complex organics. This study provided novel insights for actual operation of WWTPs.

Evaluating the efficiency of municipal wastewater treatment plant in AL-Dhibaei, Iraq

In this study, municipal wastewater treatment plant (WWTP) in AL-Dhibaei, Tikrit, Iraq was monitored over a period of one year. The data of raw sewage, which enter WWTP and treated sewage were obtained and investigated. To assess the operational performance of WWTP, the necessary pollutant indicators including biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), and dissolved phosphorus (PO4), were examined. The treatment plant reliability factor (RF) was determined in order to indicate an individual pollutant in the effluent sewage according to the permissible concentrations identified by the Iraqi Ministry of Health and Environment. RF values for BOD, COD, and PO4 were 0.56, 0.82, and 0.4, respectively, which indicated proper performance since RF values below 1. In addition, the removal efficiency for (BOD, COD, and PO4), exceeded the minimum required reduction; 43.75, 18.25, and 60.5, respectively. In addition, the stability of mixed liquor volatile suspended solids (MLVSS) to mixed liquor suspended solids (MLSS) ratio was determined and its variation was in the range of 0.565-1.225, indicating a proper performance. The sludge volume index (SVI) values were below 50 mg L-1 and its range (5.68 – 27.27 mg L-1), which was associated with efficient treatment interpretations at most of the time.

Enantioselective Monitoring of Biodegradation of Ketamine and Its Metabolite Norketamine by Liquid Chromatography

Ketamine (K) and its main metabolite, norketamine (NK), are chiral compounds that have been found in effluents from wastewater treatment plants (WWTPs) and aquatic environments. Little is known about their enantioselective biodegradation during sewage treatment; however, this information is pivotal for risk assessment, the evaluation of WWTP performance and wastewater epidemiological studies. The aim of this study was to investigate the biodegradation pattern of the enantiomers of K by activated sludge (AS) from a WWTP. For that, an enantioselective liquid chromatography with diode array detection (LC-DAD) method was developed and validated to quantify the enantiomers of K and NK. Both K and NK enantiomers were separated, in the same chromatographic run, using a Lux® 3 µm cellulose-4 analytical column under isocratic elution mode. The method was demonstrated to be linear (r2 > 0.99) and precise (<11.3%). Accuracy ranged between 85.9 and 113.6% and recovery ranged between 50.1 and 86.9%. The limit of quantification was 1.25 µg/mL for the enantiomers of NK and 2.5 µg/mL for K. The method was applied to monitor the biodegradation assay of the enantiomers of K by AS for 14 days. K was poorly biodegraded, less than 15% for both enantiomers, and enantioselectivity in the biodegradation was not observed. The metabolite NK and other possible degradation products were not detected. This work reports, for the first time, the behavior of both enantiomers of K in biodegradation studies.

Evaluation of Dairy Wastewater Treatment Systems Using Carbon Footprint Analysis

Modernisation of municipal and industrial wastewater treatment plants (WWTPs) should be carried out, taking into account its impact on global warming, e.g., through carbon footprint (CF) analysis. An important industrial sector in Poland is the dairy industry. In dairy WWTPs, the aerobic sewage sludge stabilisation applied thus far is being replaced by the anaerobic process. This change is positive due to the possibility of energy production, but it is unclear how it affects greenhouse gases (GHG) emissions. The aim of the research was to perform CF analysis for two scenarios of dairy WWTP operation. The analysis was based on the real operating data of the current system (current scenario) and project of its modernisation (alternative scenario). The current scenario consists of mechanical and dissolved air flotation (DAF) treatment, biological treatment in sequence batch reactors (SBRs), aerobic sewage sludge stabilisation and its final farmland usage. The alternative scenario assumes replacing aerobic stabilisation with anaerobic stabilisation and a combined heat and power (CHP) system. The CF calculations were based on empirical models, taking into account different emission input parameters, expressed in CO2 equivalents (CO2e). The total CF of the current scenario was 22 kg CO2e PE−1 year−1, while the alternative was 45 kg CO2e PE−1 year−1. The largest share in the current scenario belongs to emissions from WWTPs and energy use, while in the alternative, there is the addition of emissions from biogas use.

Stepwise alkaline treatment coupled with ammonia stripping to enhance short-chain fatty acids production from waste activated sludge

To recover resource from waste activated sludge (WAS) is of great significance. This study proposed a promising way, i.e., stepwise alkaline treatment coupled with ammonia stripping, to remarkably enhance short-chain fatty acids (SCFAs) production from WAS anaerobic digestion. The maximal production of SCFAs, with the value of 323 mg COD/g volatile suspended solid, was obtained with first initial pH = 10 adjustment followed by second initial pH = 10 adjustment on third day coupled with ammonia stripping. Mechanistic studies showed that solubilization of both extracellular polymeric substances and cells could be accelerated by stepwise initial pH = 10 adjustment. However, without ammonia stripping, the activities of either acidogens or methanogens could be inhibited by free ammonia formed under alkaline conditions; positively, anaerobes related to SCFAs production were enriched with ammonia stripping. Moreover, the proposed strategy can simultaneously achieve nitrogen and carbon recovery, providing some solutions for the carbon–neutral operation of wastewater treatment plants.

Elucidate microbial characteristics in a full-scale treatment plant for offshore oil produced wastewater

Oil-produced wastewater treatment plants, especially those involving biological treatment processes, harbor rich and diverse microbes. However, knowledge of microbial ecology and microbial interactions determining the efficiency of plants for oil-produced wastewater is limited. Here, we performed 16S rDNA amplicon sequencing to elucidate the microbial composition and potential microbial functions in a full-scale well-worked offshore oil-produced wastewater treatment plant. Results showed that microbes that inhabited the plant were diverse and originated from oil and marine associated environments. The upstream physical and chemical treatments resulted in low microbial diversity. Organic pollutants were digested in the anaerobic baffled reactor (ABR) dominantly through fermentation combined with sulfur compounds respiration. Three aerobic parallel reactors (APRs) harbored different microbial groups that performed similar potential functions, such as hydrocarbon degradation, acidogenesis, photosynthetic assimilation, and nitrogen removal. Microbial characteristics were important to the performance of oil-produced wastewater treatment plants with biological processes.

Continuous aerobic granular sludge plants: Better settling versus diffusion limitation

The application of aerobic granular sludge in continuous wastewater treatment plants is receiving increased attention. The introduction of better settling sludge in existing installations is expected to increase the plant’s treatment capacity by allowing a higher biomass concentration in the reactor. A lot of recent research has therefore focused on how to get stable granules in a continuous flow plant, which make up the majority of current infrastructure. Still, the effect of aerobic granular sludge on the treatment capacity and energy requirements has not thoroughly been studied so far and is not that straightforward. While it is clear that the introduction of aerobic granular sludge will result in better settling, it will also bring about a higher diffusion limitation – which is often overlooked. This study scrutinized the effect of better settling versus diffusion limitation in a typical continuous activated sludge plant (predenitrification type) through a simulation study. When only considering the improved settling velocity, the treatment capacity increased by 40% compared to conventional activated sludge. However, diffusion limitation could almost totally counteract the positive effect of better settling for a non-improved continuous system. The continuous system could be improved for aerobic granular sludge by increasing the aerobic reactor volume fraction, while lowering the oxygen set-point to benefit from simultaneous nitrification–denitrification. The optimization led to a 20% improvement in treatment capacity and a 10% reduced energy consumption compared to a conventional activated sludge system. Overall, the performance of continuous wastewater treatment plants could indeed benefit from the excellent settling properties of aerobic granular sludge, as long as process operation was improved in order to take into account diffusion limitation.

Evaluation of the hospital’s wastewater treatment plant in basrah province

This paper concentrates on evaluating the wastewater properties and performance of the hospital wastewater treatment plant (WWTP) for two hospitals in Basrah province Al-Taaleme hospital, and Al-Fayhaa hospital. Samples were collected from the WWTS influent and effluent then evaluated pollutants containing by using American Public Health Association (APHA) methods and in comparison to standard guidelines. Laboratory tests of wastewater were conducted to investigate ten parameters: chemical oxygen demand (COD), biochemical oxygen demand (BOD), PH, temperature, electric conductivity (E.C), total suspended solids (T.S.S), total dissolved solids (T.D.S), dissolved oxygen (DO) sulfate (SO4), phosphate (PO4), ammonia (NH3) and nitrate (NO3) which have been chosen to assess the quality of wastewater. The results showed that all pollutants were in compliance with the standard limit in Iraqi standard specification B1 for the year 1998, except for the NH3 results for Al-Fayhaa hospital (B), which were 12 mg/L while the standard was 10 mg/L, and COD effluent was exceeded the Iraqi standards for both hospitals Al-Taalemee hospital (A) and Al-Fayhaa hospital (B), which were 155 mg/L and 150 mg/L respectively while the standard was specified effluent by 100 mg/L, and for SO4 effluent was exceeded the Iraqi standards for both hospitals Al-Taalemee hospital (A) and Al-Fayhaa hospital (B) was 760 mg/L and 650 mg/L respectively while the standards were specified by 400 mg/L.

New standards at European Union level on water reuse for agricultural irrigation: Are the Spanish wastewater treatment plants ready to produce and distribute reclaimed water within the minimum quality requirements?

The new European regulation on minimum quality requirements (MQR) for water reuse (EU, 2020/741) was launched in May 2020 and describes the directives for the use of reclaimed water for agricultural irrigation. This Regulation will be directly applicable in all Member States from 26 June 2023. Since its publication in 2020, concerns have raised about potential non-compliance situations in water reuse systems. The present study represents a case study where three different water reuse systems have been monitored to establish their compliance with the MQR. Each water reuse system includes a wastewater treatment plant (WWTP), a distribution/storage system and an end-user point, where water is used for irrigation of leafy greens. The selected water reuse systems allowed us to compare the efficacy of water treatments implemented in two WWTPs as well as the impact of three different irrigation systems (drip, furrow and overhead irrigation). The presence and concentration of indicator microorganisms (Escherichia coli and C. perfringens spores) as well as pathogenic bacteria (Shiga toxin-producing, E. coli (STEC), E. coli O157:H7, and Salmonella spp.) were monitored in different sampling points (influent and effluent of the WWTPs, water reservoirs located at the distribution system and the end-user point at the irrigation system as well as in the leafy greens during their growing cycle. Average levels of E. coli (0.73 ± 1.20 log cfu E. coli/100 mL) obtained at the point where the WWTP operator delivers reclaimed water to the next actor in the chain, defined in the European regulation as the ‘point of compliance’, were within the established MQR (<1 log cfu/100 mL) (EU, 2020/741). On the other hand, average levels of E. coli at the end-user point (1.0 ± 1.2 log cfu/100 mL) were below the recommended threshold (2 log cfu E. coli/100 mL) for irrigation water based on the guidance document on microbiological risks in fresh fruits and vegetables at primary production (EC, 2017/C_163/01). However, several outlier points were observed among the samples taken at the irrigation point, which were linked to a specific cross-contamination event within the distribution/storage system. Regarding pathogenic bacteria, water samples from the influent of the WWTPs showed a 100% prevalence, while only 5% of the effluent samples were positive for any of the monitored pathogenic bacteria. Obtained results indicate that reclaimed water produced in the selected water reuse system is suitable to be used as irrigation water. However, efforts are necessary not only in the establishment of advance disinfection treatments but also in the maintenance of the distribution/storage systems.

A Bayesian-SWMM coupled stochastic model developed to reconstruct the complete profile of an unknown discharging incidence in sewer networks

Unknown illicit discharges from manufactories often contain toxic chemical matters that are detrimental to the receiving waterbody by deteriorating the performance of wastewater treatment plants. Numerical models that identify these sources and reconstruct the discharging profiles are highly desired for environment management purpose. In this study, a stochastic source identification model that couples Bayesian inference with SWMM is developed to reconstruct the profile of an instantaneous dumpling incidence in sewer networks. The unknown source parameters include location, dumping rate and time of the dumping incidence. Key factors that impact the convergence and performance of the model including walking step size, numbers of unknown source parameters and numbers of monitoring sites are investigated. Results show that the Bayesian-SWMM coupled model is effective and accurate in identifying the unknown sources parameters in an instantaneous dumping event. It is also found that walking step size is crucial for the results to converge to true solutions. Furthermore, it shows that the identified results are highly dependent on the numbers of unknown source parameters. More unknowns result to unsatisfying results. However, the study shows that this limitation could be significantly reduced by using more monitoring site data. One contribution of the study is that errors from measurements and numerical simulation are considered in the identification while results are presented in probabilities with all possible values revealed. This feature is highly practical and efficient when it comes to assist further field screening efforts to pinpoint the true sources.

Editorial: Design, operation and economics of large wastewater treatment plants.

Editorial: Design, operation and economics of large wastewater treatment plants.

Valorisation of residues from municipal wastewater sieving through anaerobic (co-)digestion with biological sludge.

The Circular and Green Economy principles is inspiring new approaches to municipal wastewater treatment plants (MWWTPs) design and operation. Recently, an ever-growing interest is devoted to exploring the alternatives for switching the WWTPs from being able to 'simply' removing contaminants from water to biorefinery-like plants where energy and material can be recovered. In this perspective, both wastewater and residues from process can be valorised for recovering nutrients (N and P), producing value added products (i.e. biopolymers), energy vectors and biofuels (i.e. bio-H2, bio-CH4 and bioethanol). As an additional benefit, changing the approach for WWTPs design and operation will decrease the overall amount of landfilled residues. In this context, the present research is aimed at evaluating the CH4 production potential of MWW screening units' residues. While such a stream is typically landfilled, the expected progressive increase of biodegradable matter content due to the ban on single-use plastic along with the boost of bioplastics makes the investigation of different biochemical valorisation routes more and more interesting from an environmental and economical perspective. Thus, a full-scale data collection campaign was performed to gain information on screening residues amount and properties and to analyse the relationship with influent flowrate. The most relevant residue properties were measured, and lab-scale tests were carried out to evaluate the bio-CH4 potential.

REGULATION OF INDUSTRIAL WASTEWATER DISCHARGED TO THE CENTRALIZED WATER DISPOSAL SYSTEM OF SETTLEMENTS OF THE REPUBLIC OF BELARUS

Rationing of industrial wastewater when discharging into a centralized sewerage system of settlements is one of the strategic directions in the field of environmental protection. Most enterprises discharge industrial wastewater into a centralized wastewater system without preliminary treatment, which disrupts the operation of wastewater treatment plants and reduces the efficiency of wastewater treatment and leads to the discharge of insufficiently treated wastewater into water bodies. The establishment of direct norms in the form of sectoral permissible concentrations of pollutants in industrial wastewater when they are discharged into centralized sewerage systems is not always possible, which required the development of a methodology that makes it possible to calculate the intake of pollutants as part of industrial wastewater into centralized sewerage systems. &nbsp; &nbsp; &nbsp; &nbsp