Processes In Wastewater Treatment Plants Research Articles

Coagulant and flocculant effect of Opuntia ficus-indica in water treatment

One of the most relevant processes in potable and wastewater treatment plants is coagulation-flocculation, which gives rise to the destabilization of dissolving solids, for the subsequent generation of flocs using a coagulating agent. Aluminum sulfate (Al2(SO4)3) is the most used coagulant internationally, due to its efficiency and low cost. However, its utilization can leave a residue of aluminum in water and bring with it a variety of health problems due to its bioaccumulative characteristics, implying both the deterioration of ecosystems and problems for human health. In this regard, it is necessary to establish alternatives that avoid the permanence of this heavy metal in water, so that the mucilage of Opuntia ficus-indica becomes a natural coagulant of great interest. Likewise, it is a sustainable alternative for water treatment, given its characteristics of biodegradability, low toxicity, commercial cost, relative abundance, renewability, and high efficiency, allowing a low generation of sludge, which can be biodegraded through a fair treatment with a high valuation spectrum

Characterization and removal of microplastics in the Guheshwori Wastewater Treatment Plant, Nepal

Contamination of river water systems by microplastic particles (MPPs) is one of the emerging global environmental concerns with potentially widespread ecological, socioeconomic, and health implications. A wastewater treatment plant (WWTP) processes and treats wastewater to remove pollutants and release safe water into the environment. There has been limited research on the characterization of microplastics and their removal in WWTP in South Asia. In this work, we report on the characterization of microplastics in wastewater and sludge samples (n = 300) from Guheshwori WWTP located on the bank of the Bagmati River in Kathmandu city, Nepal representing inlet, secondary aeration tank (SAT), outlet, and sludge from November 2021 to November 2022. On average, we detected 31.2 ± 17.3 MPPs/L, 11.2 ± 9.4 MPPs/L, 8.5 ± 5.6 MPPs/L, and 6.6 ± 4.8 MPPs/g in the samples collected from inlet, SAT, outlet, and sludge, respectively. Commonly found MPPs were in the form of fiber, fragments, foam, and pellets. Largely, MPPs were red, yellow, white, blue, and black. Among the 44 μm – 150 μm, 150 μm – 500 μm and 500 μm – 5 mm categories of size fractions, the most dominant fractions were 500 μm – 150 μm in inlet, SAT, and sludge, and 150 μm – 44 μm in the outlet sampling unit. The Guheshwori WWTP was able to remove 72.5 % of MPPs on average, that mostly occurred in the inlet. The effluent released into the river and the sludge still contained a significant number of MPPs.

EVALUATION OF THE CARBON FOOTPRINT IN THE TREATMENT OF URBAN WASTEWATER IN THE CANARY ISLANDS (SPAIN)

ABSTRACT: Wastewater treatment plants play an important role within the urban water cycle to prevent the natural water environment and human health from being negatively affected by human activities. However, wastewater treatment processes, such as effluent discharge and indirect emissions resulting from energy or chemical production, also negatively affect the environment. Footprints have been used to track human influence on the environment in different areas of interest and have been applied to assess the sustainability of wastewater treatment plants. In this article, a comprehensive review of footprint assessment was investigated to evaluate the wastewater treatment process in wastewater treatment plants. The review showed that carbon footprinting was used to assess the sustainability of WWTPs, and that other footprint assessment applications (such as nitrogen and phosphorus footprinting) were also introduced to assess eutrophication of water bodies. To promote the application of footprint assessment, this article regulates the study objectives, frameworks, system boundaries, data processing methods, and the resulting interpretation process. The pros and cons of the footprint assessments were discussed and investigated in detail, examining the CO2 production on each island of the Canary archipelago, and several suggestions were proposed to improve the footprint assessments. Analysis of footprint assessments at different wastewater treatment plants revealed that wastewater treatment technologies and scales had a significant impact on footprints. Furthermore, research hotspots identified using a keyword network diagram showed that the water-carbon-energy nexus was a promising direction for future studies. The purpose of the study is to improve the reduction of the carbon footprint both at the level of direct and indirect emissions factors using new tools and methodologies. Key Words: Footprint; Waste water; Canary Islands

Enhancing Microplastics Recovery from Complex Sludge Samples Using COD-Guided Pretreatment

Given the society’s continuous reliance on plastic materials, large amounts of micron-sized plastic particles (i.e., microplastics, MPs) reach wastewater treatment plants (WWTPs) every day. Despite their effective removal from influent wastewater, over 90% of MPs in WWTPs are accumulated in sludge. Yet, there is no universally accepted method for quantifying and identifying MPs, obscuring our understanding of this pollution’s extent. Therefore, this study aims to develop a chemical oxygen demand (COD) based repeatable method for MPs analysis in sludge, which is a very complex, MPs-laden by product of WWTPs. The developed method is unique in that it removes the organic substances interfering with polymer analysis by monitoring the COD of sludge. Upon 90% of organic matter removal, MPs are extracted from the medium by a two-step density-based separation, sieved, stained with Nile Red, and counted using fluorescence microscopy. Moreover, quality assurance and quality control strategies including blank preparation and spike-and-recovery test procedures are followed. The protocol ensures a minimum 80% recovery rate of various MPs from both waste activated sludge (WAS) and wastewater samples, aligning with recommended standards. Crucially, the method preserves the chemical identity of MPs. Application of the protocol revealed that urban WWTP WAS had 475 MPs/g TS; industrial influent and effluents wastewater had 73 and 26 MPs/L; and industrial secondary and dewatered sludge had 114 and 132 MPs/g TS, consistent with the literature. This demonstrates the method’s robustness by revealing MPs reduction within the WWTP process and sludge accumulation as treatment progresses.Graphical

The proliferation of antibiotic resistance genes (ARGs) and microbial communities in industrial wastewater treatment plant treating N,N-dimethylformamide (DMF) by AAO process.

The excessive use of antibiotics has resulted in the contamination of the environment with antibiotic resistance genes (ARGs), posing a significant threat to public health. Wastewater treatment plants (WWTPs) are known to be reservoirs of ARGs and considered to be hotspots for horizontal gene transfer (HGT) between bacterial communities. However, most studies focused on the distribution and dissemination of ARGs in hospital and urban WWTPs, and little is known about their fate in industrial WWTPs. In this study, collected the 15 wastewater samples containing N,N-dimethylformamide (DMF) from five stages of the anaerobic anoxic aerobic (AAO) process in an industrial WWTPs. The findings revealed a stepwise decrease in DMF and chemical oxygen demand (COD) content with the progression of treatment. However, the number and abundances of ARGs increase in the effluents of biological treatments. Furthermore, the residues of DMF and the treatment process altered the structure of the bacterial community. The correlation analysis indicated that the shift in bacterial community structures might be the main driver for the dynamics change of ARGs. Interestingly, observed that the AAO process may acted as a microbial source and increased the total abundance of ARGs instead of attenuating it. Additionally, found that non-pathogenic bacteria had higher ARGs abundance than pathogenic bacteria in effluents. The study provides insights into the microbial community structure and the mechanisms that drive the variation in ARGs abundance in industrial WWTPs.

Multi-Objective Optimization Based on Simulation Integrated Pareto Analysis to Achieve Low-Carbon and Economical Operation of a Wastewater Treatment Plant

It is essential to reduce carbon emissions in wastewater treatment plants (WWTPs) to achieve carbon neutrality in society. However, current optimization of WWTPs prioritizes the operation cost index (OCI) and effluent quality index (EQI) over greenhouse gas (GHG) emissions. This study aims to conduct a multi-objective optimization of a WWTP, considering GHG emissions, EQI, and OCI. The anaerobic-anoxic-oxic integrated membrane bioreactor (AAO-MBR) process in an actual WWTP was selected as a typical case, tens of thousands of scenarios with combinations of six operational parameters (dissolved oxygen (DO), external carbon resource (ECR), poly aluminum chloride (PAC), internal reflux ratio (IRR), external reflux ratio (ERR), and sludge discharge (SD)) were simulated by GPS-X software (Hydromantics 8.0.1). It was shown that ECR has the greatest impact on optimization objectives. In the optimal scenario, the main parameters of ATDO, MTDO, IRR, and ERR were 0.1 mg/L, 4 mg/L, 50%, and 100%, respectively. The EQI, OCI, and GHG of the best scenario were 0.046 kg/m3, 0.27 ¥/m3, and 0.51 kgCO2/m3, which were 2.1%, 72.2%, and 34.6% better than the current situation of the case WWTP, respectively. This study provides an effective method for realizing low-carbon and economical operation of WWTPs.

Regulatory of salinity on assembly of activated sludge microbial communities and nitrogen transformation potential in industrial plants of the lower Yangtze River basin

This study aims to thoroughly investigate the impact mode of salinity carried by industrial wastewater on the anaerobic-anoxic-oxic (A2O) sludge in wastewater treatment plants (WWTPs). Through comprehensive investigation of the A2O stage activated sludge (AS) from 19 industrial WWTPs in the downstream area of the Yangtze River, China, A total of 38 samples of anaerobic sludge and oxic sludge were collected and analyzed. We found that salinity stress significantly inhibits the growth of the AS community, particularly evident in the anaerobic sludge community. Furthermore, the high-saline environment induces changes in the structure and functional patterns of the AS community, leading to intensive interactions and resource exchanges among microorganisms. Halophilic microorganisms may play a crucial role in this process, significantly impacting the overall community structure, especially in the oxic sludge community. Additionally, salinity stress not only suppresses the nitrogen transformation potential of the AS but also leads to the accumulation of nitrite, thereby increasing the emission potential of both NO and N2O, exacerbating the greenhouse effect of the A2O process in industrial WWTPs. The findings of this study provide necessary theoretical support for maintaining the long-term stable operation of the A2O sludge system in industrial WWTPs, reducing carbon footprint, and improving nitrogen removal efficiency.

Feasibility of ultrafiltration-based processes for simultaneous removal of trace-level ofloxacin and sulfamethazine from the effluent of WWTPs

The emergence of emerging contaminants, especially antibiotics, poses a great challenge to the traditional treatment processes in wastewater treatment plants (WWTPs) due to their non-biodegradable and toxic properties. In this study, the potential of UF-based processes for concurrently removing trace-amount (ng/L-μg/L) ofloxacin (OFC) and sulfamethazine (SMT) from the real effluent of WWTPs was assessed. The operational conditions of single UF were firstly optimized including molecular weight cut-off (50 kDa) and filtration pressure (25 kPa) with the maximum OFC and SMT retention of 60.65 ± 1.61 % and 50.21 ± 2.11 %, respectively. The impacts of dissolved organic matter (DOM) and NO3− on UF for the concurrent abatement of antibiotics were explored. It was noteworthy that DOM (below 25 mg/L) could enhance OFC abatement by UF, whereas NO3− was adverse for the concurrent abatement of OFC and SMT. The optimal combining sequence of UF and O3 processes for concurrently removing OFC and SMT from the effluent of WWTPs was also investigated. Compared with O3-UF, UF-O3 demonstrated a higher efficiency for concurrent elimination of OFC and SMT. The tech-economic feasibility analysis indicated that UF-O3 could provide one promising option for simultaneously removing OFC and SMT from the WWTPs effluent due to its relatively low potential ecological risks based on UV254 removal, acute toxicity and three-dimensional fluorescence spectroscopy (3D-EEM) and excellent cost-effectiveness (the operating cost is about 0.35 CNY/m3).

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.

Performance evaluation and parameter estimation of the advanced primary filtration (APF) process in wastewater treatment plants

Conventional technologies employed in wastewater treatment plants (WWTPs) demand significant energy consumption. Concurrently, the wastewater infrastructure is experiencing a heavy strain as a result of the increased influent loads and pollutants. Advanced primary filtration (APF) is an emerging wastewater treatment process for early removal of suspended solids from raw wastewater. In this work, the APF process comprises of a two-stage filtration system, consisting of a proprietary rotating belt filter (RBF) (collectively known as microsieve) followed by a proprietary continuous backwash upflow media filter (CBUMF). The principal focus of this study is the assessment of the APF process performance, and the prediction of the total suspended solids (TSS) effluent concentrations of the APF process, using a parameter estimation method. According to pilot scale experimental results, the percentages of TSS (average TSS removal rate of 51 %) and biological oxygen demand (BOD5) (average BOD5 removal rate of 30 %), removed by the microsieve were notably higher compared to conventional primary treatment (sedimentation). The removal efficiency of the APF process during stable operation, varied from 69 to 86 % for TSS, as compared to 50–70 % typically achieved with primary sedimentation. The removal performance of BOD5 varied from 44 to 82 %, as compared to 25 to 40 % typically achieved with primary sedimentation. The chemical oxygen demand (COD) removal rates for the APF process ranged between 62 and 90%, as compared to 25–40 % typically achieved with primary sedimentation. The early removal of TSS prior to aeration tank has the potential to significantly enhance the capacity of the WWTP and decrease the energy requirements of the aeration tank. A high degree of concordance between model predictions and experimental data was observed. This study demonstrated the potential of using the APF process for the early removal of TSS from raw municipal wastewater just upstream of the aeration tank.

Accounting for the microbial assembly of each process in wastewater treatment plants (WWTPs): study of four WWTPs receiving similar influent streams.

We evaluated a unique model in which four full-scale wastewater treatment plants (WWTPs) with the same treatment schematic and fed with similar influent wastewater were tracked over an 8-month period to determine whether the community assembly would differ in the activated sludge (AS) and sand filtration (SF) stages. For each WWTP, AS and SF achieved an average of 1-log10 (90%) and <0.02-log10 (5%) reduction of total cells, respectively. Despite the removal of cells, both AS and SF had a higher alpha and beta diversity compared to the influent microbial community. Using the Sloan neutral model, it was observed that AS and SF were individually dominated by different assembly processes. Specifically, microorganisms from influent to AS were predominantly determined by the selective niche process for all WWTPs, while the microbial community in the SF was relatively favored by a stochastic, random migration process, except two WWTPs. AS also contributed more to the final effluent microbial community compared with the SF. Given that each WWTP operates the AS independently and that there is a niche selection process driven mainly by the chemical oxygen demand concentration, operational taxonomic units unique to each of the WWTPs were also identified. The findings from this study indicate that each WWTP has its distinct microbial signature and could be used for source-tracking purposes.IMPORTANCEThis study provided a novel concept that microorganisms follow a niche assembly in the activated sludge (AS) tank and that the AS contributed more than the sand filtration process toward the final microbial signature that is unique to each treatment plant. This observation highlights the importance of understanding the microbial community selected by the AS stage, which could contribute toward source-tracking the effluent from different wastewater treatment plants.

Homogeneous oxidation of EE2 by ozone: Influencing factors, degradation pathway, and toxicity assessment

17α-Ethinylestradiol(EE2) is a common hormone drug that plays an essential role in endocrine and reproductive health. However, estrogens are degraded only to a limited extent by humans and livestock themselves, and most of them are excreted in undegraded or partially degraded form from human and livestock feces and urine into water bodies, posing a austere ecological risk. Of the known degradation processes in wastewater treatment plants, ozone-induced advanced oxidation shows tremendous potential. At the same time, the limitations of the test methodology makes it extremely difficult to do an in-depth investigation of the degradation mechanism. In this study, the influencing factors, including ozone dose, initial concentration, and pH were investigated. The degradation pathways of EE2 were analyzed by combing with quantum chemical calculations and high performance liquid chromatography coupled with quadrupole-time of flight tandem mass spectrometry (HPLC-Q-TOF-MS). Toxicity Estimation Software Tool (T.E.S.T) evaluated EE2 and its degradation intermediates for a variety of toxicities. And the results showed that reactions such as oxidative hydroxylation of the benzene ring and oxidative ring opening of the aliphatic ring mainly occurred during the degradation of estrogens, and the reaction was initially fast. The degradation effect is lower under neutral conditions, and the acidity and alkalinity of the solution are reduced with the reaction process under strong acid and alkaline conditions. The products of the experimental reactions reflect the active site, e.g., product P1 reflects C(5) as the site of easy reaction, which is consistent with previous theoretical predictions, suggesting that theoretical studies can provide complementary information on oxidation. The toxicity of intermediates obtained from partial ozone degradation improved compared to EE2, and the mutagenicity of EE2 was elevated greatly. However, single ozonation significantly diminished the developmental toxicity and bioaccumulation factor for a large proportion of intermediates. This work may contribute to the theoretical foundation for the practical application of ozone oxidation of environmental estrogens.

Occupational exposure to severe acute respiratory syndrome coronavirus-2 in wastewater and its implications in the gulf region

ABSTRACT Coronavirus disease-19 (COVID-19) is a viral disease caused by severe acute respiratory syndrome corona virus-2(SARS-CoV-2) that affects the respiratory system and causes varying symptoms including fever and cough. Throughout the current COVID-19 pandemic, several studies have confirmed that raw wastewater may contain the SARS-CoV-2 genome as the virus is shed from excreta of infected individuals. This review examined the literature from 2020 to 2023 on occupational health, safety, wastewater, and SARS-CoV-2, excluding clinical aspects. Relevant publications from previous epidemics (SARS-CoV-1 and Middle East respiratory syndrome coronavirus) were also considered. Quantitative microbial risk assessments have been used previously and in the current pandemic to assess the risk of inhaling aerosolized SARS-CoV-2 generated during the wastewater treatment processes. Meanwhile, water-based epidemiology (WBE) has been effective in identifying and tracking high incidence hotspots as well as mitigating the spread of the disease. Inefficient processes in wastewater treatment plants may be a source of SARS-CoV-2 transmission to workers employed at such plants as well as to personnel handling treated wastewater for reuse purposes such as irrigation and recreation, more so in the gulf countries owing to the extreme limitation of freshwater in this region; thus, exploring the implications of SARS-CoV-2 genome in wastewater to safeguard occupational and public health is crucial. WBE can assist in the pandemic prevention and control measures by investigating SARS-CoV-2 virus survival and transmission through the wastewater treatment and effective control measures. This review presents an overview of occupational exposure to SARS-CoV-2 from wastewater aerosols and elucidates its implications, while recommending preventive and mitigation measures.

FePO4 activated sulfite autoxidation for simultaneous pollutant degradation and phosphorus release

FePO4 (FP) as a precursor of lithium iron phosphate batteries has been mass-produced in recent years and may face the problem of overproduction. Also, the phosphorus removal process in wastewater treatment plants produces large amounts of sludge containing FP. It is a huge waste of both iron and phosphorus resources if such FP cannot be utilized. This work explores a new strategy for utilizing FP to activate sulfite (S(IV)) autoxidation for simultaneous pollutant degradation and phosphorus release in water. Acid orange 7 (AO7) and several pharmaceutical and personal care products (PPCPs) were chosen as the target pollutants for the FP‒S(IV) system and the influence of pH, FP and S(IV) dosage were investigated. Typically, up to 89.5% AO7 (10 mg L−1) and above 60% PPCPs (10 μM) were oxidized within 90 min by adding 1 g L−1 FP and 2 mM S(IV) into the water at the initial pH 4.0. Results of quenching experiments and electron spin resonance analysis confirmed SO5•− as the dominant reactive species for AO7 oxidation. Meanwhile, two stages of phosphorus release from FP were observed along with the AO7 oxidation and their linear correlation over the pH range 3.0–8.0 was proven. The first stage (0–5 min) was thought to be dependent on the initial pH and was obviously faster than the second stage (10–45 min), whose rate increased linearly with S(IV) dosage. Phosphorus released high up to 24.3 μM at 90 min with 4 mM S(IV). Moreover, the mechanisms of FP activated sulfite autoxidation as well as phosphorus release were proposed, and the AO7 degradation pathway was investigated. This study provides a novel possibility for FP waste utilization and potential recovery of phosphorus resources.

Laccases as Effective Tools in the Removal of Pharmaceutical Products from Aquatic Systems.

This review aims to provide a comprehensive overview of the application of bacterial and fungal laccases for the removal of pharmaceuticals from the environment. Laccases were evaluated for their efficacy in degrading pharmaceutical substances across various categories, including analgesics, antibiotics, antiepileptics, antirheumatic drugs, cytostatics, hormones, anxiolytics, and sympatholytics. The capability of laccases to degrade or biotransform these drugs was found to be dependent on their structural characteristics. The formation of di-, oligo- and polymers of the parent compound has been observed using the laccase mediator system (LMS), which is advantageous in terms of their removal via commonly used processes in wastewater treatment plants (WWTPs). Notably, certain pharmaceuticals such as tetracycline antibiotics or estrogen hormones exhibited degradation or even mineralization when subjected to laccase treatment. Employing enzyme pretreatment mitigated the toxic effects of degradation products compared to the parent drug. However, when utilizing the LMS, careful mediator selection is essential to prevent potential increases in environment toxicity. Laccases demonstrate efficiency in pharmaceutical removal within WWTPs, operating efficiently under WWTP conditions without necessitating isolation.

Molecular characterization of human bocavirus in municipal wastewaters using amplicon target sequencing

Human bocavirus (HBoV) is an emerging health concern worldwide, associated with range of clinical manifestations, including gastroenteritis and respiratory infections. Therefore, it is crucial to comprehend and minimize their prevalence in different systems. In this study, we conducted regular sampling throughout the year in two different sizes and work processes of wastewater treatment plants (WWTPs) in Tianjin, China. Our objective was to investigate the occurrence, prevalence, and endurance of HBoV in wastewater, while also evaluating the efficacy of amplicon target sequencing in directly detecting HBoV in wastewater. At two WWTPs, HBoV2 (45.51 %—45.67 %) and HBoV3 (38.30 %—40.25 %) were the most common genotypes identified, and the mean concentration range of HBoV was 2.54—7.40 log10 equivalent copies/l as determined by multiplex real-time quantitative PCR assay. A positive rate of HBoV was found in 96.6 % (29/30) samples of A-WWTP, and 96.6 % (26/27) samples of B-WWTP. The phylogenetic analysis indicated that the nucleotide similarity between the HBoV DNA sequences to the reference HBoV sequences published globally ranged from 90.14 %—100 %. A significant variation in the read abundance of HBoV2 and HBoV3 in two wastewater treatment plants (p < 0.05) was detected, specifically in the Winter and Summer seasons. The findings revealed a strong correlation between the genotypes detected in wastewater and the clinical data across various regions in China. In addition, it is worth mentioning that HBoV4 was exclusively detected in wastewater and not found in the clinical samples from patients. This study highlights the high prevalence of human bocavirus in municipal wastewater. This finding illustrates that amplicon target sequencing can amplify a wide variety of viruses, enabling the identification of newly discovered viruses.

Steady-State and Dynamic Simulation for Wastewater Treatment Plant Management: Case Study of Maghnia City, North-West Algeria

Given the critical importance of addressing effluent quality concerns, the present study was dedicated to developing a dynamic simulation model based on the Activated Sludge Model 1 (ASM1) of a wastewater treatment plant located in Maghnia City, Algeria. The model calibration process involved collecting and analyzing 56 samples from the plant over a period of 18 months (from July 2021 to January 2023). Thirteen physicochemical parameters were analyzed to identify the variations in their water quality over time. Stoichiometric and kinetic parameters were adjusted during the plant calibration process. These modifications resulted in a reasonable alignment with the investigated variables, enabling the accurate prediction of the wastewater treatment plants (WWTPs)’ steady-state behavior regarding the removal measurements of chemical oxygen demand (COD), total suspended solids (TSS), and ammonium (NH4-N). The model was validated using 14-day measurements spanning a 4-month duration, and the results indicated good agreement between the observed and simulated effluent variable of chemical oxygen demand (COD) with a root mean square error (RMSE) of 23%. These findings highlight the utility of the ASM1 Model in comprehending and managing the intricate dynamics of the activated sludge process in wastewater treatment plants.

Nitrous Oxide Generation, Influencing Factors and Emission Reduction in Anaerobic-Anoxic-Oxic Process Wastewater Treatment Plant

To achieve the reduction of emissions and control of non-CO2 greenhouse gases in municipal wastewater treatment plants, this study conducted a one-year monitoring of N2O in the A2O process of a large municipal wastewater treatment plant in Beijing. N2O released from the water surface of the A2O process was collected by using a gas flux chamber, and the key influencing factors affecting N2O were analysed using statistics. The results showed that N2O was not easy to be released under non-aerated conditions, and the aerobic zone was its main emission area. Temperature leads to high N2O emissions in winter and low in summer. Correlation analyses showed that NO2-N is one of the most critical factors affecting N2O production, and its accumulation level directly affects the amount of N2O produced in the system. DO also has a great influence on the production of N2O, and the amount of N2O produced decreases with the increase of the DO concentration, and the effect on the enzyme activity also makes the pH have a significant effect on the production of N2O.

Analysing the chemical standards of the Fergana Mekhmash wastewater treatment plant and environmental processing

Protection of the environment from pollution and rational use of natural resources is one of the main problems of the present time. Saving and protecting water resources is the solution to this problem. Wastewater (dirty water from industrial and domestic enterprises) and stormwater treatment are an important part of nature protection. This article is the study of the technology of industrial wastewater treatment and the composition of dry residues left after water treatment from the galvanic department of the MexMash plant in the city of Fergana. Redirection of ZnO, Fe2O3, FeO and P2O5 contained in waste, application of ecological treatment of wastewater. In the industrial production enterprise of the city of Fergana, it was considered to study the composition of the waste produced as a result of the treatment of wastewater generated during the production process and to direct it to production.

Development and application of the UVC LED-based spectrophotometer for high frequency online monitoring of nitrate concentration in municipal wastewater

Developing a fast, sensitive and stable sensor for online monitoring nitrate concentration is an urgent need for the optimization of denitrification processes in wastewater treatment plants (WWTPs). In this study, the miniaturized spectrophotometric nitrate sensor was developed using UVC light-emitting diodes (LEDs) coupled with AlGaN or SiC-based photodiodes. The use of novel SiC photodiodes could effectively eliminate UVB and UVA light in the 230 nm LED emission spectra. Replacing 235 nm UVC-LED with 230 nm UVC-LED could effectively increase the detection sensitivity but not the linear range that follows the Lambert-Beer's law. The influences of dissolved organic matter (DOM) on nitrate analysis could be corrected by a unified coefficient α across the NO3--N concentration ranging in 0–50 mg/L. Across the investigated WWTP samples, the correction coefficient α was mainly determined by the fractions of humic substances with apparent molecular weight (MW) of 1.5–9.0 kDa, while the degradation of the large MW proteinaceous biopolymer resulted in dramatic variations of correction coefficient α along the WWTP A/A/O process. Microfiltration membranes with pore sizes ≤ 30 µm could sufficiently eliminate the influences of particles in effluents on photometric nitrate analysis. The ultrafiltration and enhanced coagulation treatment could effectively remove the biopolymer fractions of DOM in wastewater, and thus alleviate its influences on sensitivity and accuracy of nitrate analysis. The spectrophotometric nitrate sensors were successfully applied for on-line monitoring NO3--N concentrations in the influent and effluent of denitrifying biofilter in a municipal WWTP, providing high-frequency feedback signals to precise control of feeding external carbon source.