Sewage Treatment Process Research Articles

An efficient anoxic/aerobic/aerobic/anoxic process for domestic sewage treatment: From feasibility to application.

In this paper, the anoxic/aerobic/aerobic/anoxic (AOOA) process was proposed using fixed biofilms in a continuous plug-flow multi-chamber reactor, and no sludge reflux operation was performed during the 190 days of operation. The reactor volume ratio of 1.5:2:1.5:1 (A/O/O/A) with the dissolved oxygen (DO) concentration of 2 mg L−1 in the aerobic zone was the optimal condition for reactor operation. According to the results obtained from the treatment of real domestic sewage, when the hydraulic retention time (HRT) was 6 h, the effluent of the reactor could meet the discharge standard even in cold conditions (13°C). Specifically, the elemental-sulfur-based autotrophic denitrification (ESAD) process contributed the most to the removal of total inorganic nitrogen (TIN) in the reactor. In addition, the use of vibration method was helpful in removing excess sludge from the biofilms of the reactor. Overall, the AOOA process is an efficient and convenient method for treating domestic sewage.

Intelligent Measurement and Analysis of Sewage Treatment Parameters based on Fuzzy Neural Algorithm with ARM9 Core CPU.

After entering the new century, the state continues to increase the construction of urban sewage treatment projects in response to the deteriorating water pollution situation. How to collect and analyze the sewage parameter variables in the sewage treatment process to ensure the intelligent measurement and accurate operation of the parameters in the treatment application is an urgent problem to be solved. This paper is mainly based on the computer-aided control system built by the ARM9 core embedded chip, and the feasibility and effectiveness of fuzzy neural network algorithms are discussed to improve the intelligent processing of sewage treatment parameters. After analyzing the principle and implementation flow of fuzzy control and neural network, starting from the characteristics of data collected by ARM9 core chip, the hybrid algorithm model is optimized and improved to further improve the convergence speed and accuracy of the algorithm. The simulation experiment proves that the optimized fuzzy neural control algorithm can effectively identify the dissolved oxygen, nitrate nitrogen, and other parameter data in the sewage treatment, and the recognition accuracy is very close to the true precision. Based on biosensors, the ARM9 core chip control system established by a recursive fuzzy neural network can greatly improve the tracking and control ability of parameters such as dissolved oxygen concentration and nitrate nitrogen concentration in microbial degradation. This has a good development prospect in wastewater treatment control applications. The experimental results show that the recursive fuzzy neural network algorithm proposed in this paper can dynamically track and control the nitrate concentration and dissolved oxygen concentration and ensure that the control is within the accuracy range. The accuracy of recognition is very close to the real accuracy.

Integrated Process of Ammonium Ion Adsorption by Natural Dispersed Sorbents

The process of adsorption treatment of effluents from ammonium ions is considered as an integrated two-stage process consisting of the stage of adsorption of contaminants by natural sorbents in the apparatus with a stirrer and the liquid separation stage and solid phases. Mathematical models of ammonium ions adsorption from effluents by natural dispersed sorbents are proposed, based on the assumption that the process is described by Langmuir and Friendlich isotherms. The values of ion exchange equilibrium constants for different types of natural sorbents have been established by identifying experimental data for theoretical dependences. The obtained constants can be used to calculate the average concentration of ammonium ions in the solution and in the grain of the sorbent in the process of integrated adsorption process. Based on the analysis of the research results, the optimum method of the spent sorbent separation was selected - separation of the suspension of purified ammonium-containing effluents - spent sorbent under the action of gravity. Indicators of optimization of complex process of sewage treatment from ammonium ions are offered.

Complex behavior between microplastic and antibiotic and their effect on phosphorus-removing Shewanella strain during wastewater treatment

Owing to their widespread application and use, microplastics (MPs) and antibiotics coexist in the sewage treatment systems. In this study, the effects and mechanisms of the combined stress of MPs and ciprofloxacin (CIP) on phosphorus removal by phosphorus-accumulating organisms (PAOs) were investigated. This study found that the four types of MPs and CIP exhibited different antagonistic effects on the inhibition of phosphorus removal by PAO. MPs reduced the effective concentration of CIP through adsorption and thus reduced its toxicity, which was affected by the biofilms on MPs. In addition, CIP may cause PAO to produce more extracellular polymeric substances, which reduces the physical and oxidative stress of MPs on PAO. Our results are helpful as they increase the understanding of the effects of complex emerging pollutants in sewage systems and propose measures to strengthen the biological phosphorus removal in sewage treatment processes.

APPLICATION OF ECONOMIC EVALUATION OF MEMBRANE TECHNOLOGIES FOR WASTEWATER TREATMENT

In the face of water scarcity, the world seeks to explore all available options to reduce overexploitation and so limited freshwater resources. One of the most reliable available water resources is wastewater. As the world's population grows, so do industrial, agricultural, and domestic activities, which produce large amounts of such water that can be treated and reused.
 Sewage treatment processes have been somewhat successful in wastewater treatment, but many are high-tech and cost-effective. Membrane technology has become a favorite choice for the reclamation of water from various wastewater streams for reuse.
 Organic membranes are made of synthetic organic polymers. Pressure membranes are mainly produced for separation processes (microfiltration, ultrafiltration, nanofiltration and reverse osmosis) from synthetic organic polymers. These include polyethylene (PE), polytetrafluoroethylene (PTFE), polypropylene and cellulose acetate. In addition, membranes are made of materials such as ceramics, metals, zeolites or silica. They are chemically and thermally stable and are widely used for industrial purposes such as hydrogen separation, ultrafiltration and microfiltration.
 Pressure-controlled membrane technologies are the most widely used membrane processes in wastewater treatment, from previous contamination followed by additional treatment. These processes are based on microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO). They are necessary but costly
 The choice of wastewater treatment option is based on comparative economic efficiency. The main ways to determine such efficiency are: pairwise comparison of options and determine the minimum of the reduced costs of the compared options. Pairwise comparison of options is carried out by determining the coefficients of comparative economic efficiency and payback periods of additional capital investments.

Prediction of Dissolved Oxygen Concentration in Sewage Treatment Process Based on Data Recognition Algorithm.

In order to realize the real-time and accurate prediction of dissolved oxygen concentration in the sewage treatment process, a prediction model of dissolved oxygen concentration in the sewage treatment process based on a data identification algorithm was proposed. Combined with the data characteristics of the sewage treatment process, a new sample similarity measure is defined to extract more representative modeling data. In the improved algorithm, in order to improve the quality of the initial members of the basic fireworks algorithm, the chaos algorithm is integrated. The search mechanism of the basic fireworks algorithm is improved, and the optimization process is divided into two stages based on the set criteria, and two groups are used simultaneously. The results show that compared with the basic FWA algorithm, the CFWA algorithm makes better use of the chaotic search mechanism. On the one hand, it avoids the excessive random or blind selection of the initial weight threshold of the neural network in the initial stage; on the other hand, in the optimization process of the weight threshold, two types of search mechanisms, FWA and COA, are used to give full play to their respective strengths and to continuously conduct information exchange and mutual cooperation between groups and individuals. The number of times is better than the basic FWA algorithm, and the training error and generalization error of the CFWA model in the simulation results of the soft sensor model are also better than those of the FWA model, which fully verifies the effectiveness of the CFWA algorithm. It is proved that the data recognition algorithm can effectively predict sewage treatment. It is proved that the data recognition algorithm can effectively predict the dissolved oxygen concentration in wastewater treatment process. It provides a new measurement method for some key process variables that cannot be measured or are difficult to measure in complex chemical processes.

A new insight to explore toxic Cd(II) affecting denitrification: Reaction kinetic, electron behavior and microbial community

Denitrification process is a crucial step in nitrogen removal and is more vulnerable to external shocks due to the fact that anoxic process is always located before aerobic process in conventional sewage treatment. This study aims to elaborate the nitrogen conversion characteristics by investigating denitrification kinetics, electron behavior and microbial community under Cd(II) shock. Reaction kinetics showed that 10 mg/L of Cd(II) accelerated nitrate reduction rate by 52.29% but 80 mg/L of Cd(II) severely decelerated it by 95.41% with the accumulation of nitrite. High concentration of COD (C/N = 10.4) in the system caused by Cd(II) disrupting the integrity of cell membrane (lactate dehydrogenase increased by 328.7%) was proved to induce occurrence of Dissimilatory Nitrate Reduction to Ammonia (DNRA). The electron transport system activity (ETSA), electron consumption and electron distribution were combined to reveal the electron behavior regulated by Cd(II). The electron ratio of nitrate reductase to nitrite reductase increased from 1.48 (control) to 3.91 and 3.52 (40 and 80 mg/L of Cd(II)) indicated the electrons allocating tendency and further explained the nitrite accumulation. High concentration of Cd(II) also decreased ETSA by weakening the physiological activities of flavin adenine dinucleotide, flavin mononucleotide and cytochrome c or hindered the microbes to secrete these electron carriers. Furthermore, Cd(II) inhibited dominant bacteria genera containing napA gene (Azospirillum and Thauera) and nirS gene (unclassified_c_Betaproteobacteria). Enterobacteriaceae family was found to dominate the DNRA process.

Application of Sewage Treatment Process and Reuse Technology in Municipal Engineering

Application of Sewage Treatment Process and Reuse Technology in Municipal Engineering

Implementation Analysis of Environmental Protection and Energy Saving Concept in Urban Sewage Treatment Process

Implementation Analysis of Environmental Protection and Energy Saving Concept in Urban Sewage Treatment Process

Study on Optimization of Municipal Domestic Sewage Treatment Process Design

Study on Optimization of Municipal Domestic Sewage Treatment Process Design

Online learning-empowered smart management for A2O process in sewage treatment processes

Using artificial intelligence method to describe general working process is a more meaningful and widely used idea in various practical projects. At the same time, it is also an important way to realize intelligent management. Water pollution is serious all over the world, also the intelligent management of sewage treatment has always been one of the urgent problems to be solved. For this, an intelligent management system is designed in this study to realize automatic monitoring and intelligent decision-making of sewage treatment. However, the existing technology usually trains artificial intelligence models based on historical data, and such models have some limitations in describing nonlinear and complex wastewater treatment processes. Offline machine learning lacks dynamic adaptive characteristics to scene changes. Considering this, this paper designs an online learning-empowered smart management for A2/O process in sewage treatment processes (OL-AP). Online learning is based on the new data generated by the scene transformation, so that the model can learn again and give better results. In this study, relevant simulation experiments are carried out on the sewage treatment data of a sewage treatment plant in Chongqing. Firstly, automatic data collection is realized based on the sensor network of the IoT. Then, according to the preprocessed data, the designed prediction model is trained and a set of parameters with better evaluation indexes is obtained. Finally, online learning uses the latest data samples based on the online feedback of real scenes to optimize the model by retraining and adjusting parameters.

Occurrence and removal of 25 antibiotics during sewage treatment processes and potential risk analysis.

The occurrence and removal of 25 antibiotics, including ten quinolones (QNs), four macrolides (MLs), four tetracyclines (TCs) and seven sulfonamides (SNs), were analysed at two sewage treatment plants (STPs) with different treatment units in Guangxi Province, China. The results showed that 14 and 16 antibiotics were detected in the influent of the two STPs, with concentrations ranging from 13.7-4265.2 ng/L and 14.5-10761.7 ng/L, respectively. Among the antibiotics, TCs were the main type in the study area, accounting for more than 79% of the total concentration of all antibiotics. The antibiotic removal efficiencies of the different process units ranged from -56.73% to 100.0%. It was found that the SN removal efficiency of the multistage composite mobile bed membrane bioreactor (MBBR) process was better than that of the continuous-flow Intermission biological reactor (IBR) process, while the IBR process was better than the MBBR process in terms of removing TCs and MLs; however, there was no obvious difference in the QN removal efficiencies of these two processes. Redundancy analysis (RDA) showed a strong correlation between antibiotic concentration and chemical oxygen demand (COD). Risk assessments indicated that algae, followed by invertebrates and fish, were the most sensitive aquatic organisms to the detected antibiotics.

A novel multistage anoxic/aerobic process with sludge regeneration zone (R-MAO) for advanced nitrogen removal from domestic sewage

To achieve advanced nitrogen removal from actual municipal sewage, a novel multistage anoxic/aerobic process with sludge regeneration zone (R-MAO) was developed. The reactor was used to treat actual domestic sewage and the nitrogen removal capacity of the sludge regeneration zone (R zone) was investigated during the long-term operation. The best performance was obtained at the R zone's Oxidation-Reduction Potential (ORP) of -50±30 mV and hydraulic residence times (HRT) of 1.2 hr. The average effluent COD, TN, NH4+-N and NO3−-N of the R-MAO process were 18.0±2.3, 7.5±0.6, 1.0±0.5 and 4.6±0.4 mg/L, respectively, with the corresponding removal efficiency of COD, TN and NH4+-N were 92.9%±1.0%, 84.1%±1.5% and 97.5%±1.1%. Compared to the sole MAO system, the TN removal efficiency of the R-MAO increased by 10.1%. Besides, under the optimal conditions, the contribution of the R zone in the R-MAO that removal COD, TN, NH4+-N and NO3−-N were 0.36, 0.15, 0.032 and 0.82 g/day. High-throughput sequencing results showed that uncultured_bacterium_f_Burkholderiaceae (5.20%), OLB8 (1.04%) and Ottowia (1.03%) played an important role in denitrification in the R zone. This study provided effective guidance for the design and operation of the R-MAO process in domestic sewage treatment.

Estrogenic activity and ecological risk of steroids, bisphenol A and phthalates after secondary and tertiary sewage treatment processes

Effluents of sewage treatment plants (STPs) are an important source of estrogenic substances to the receiving water bodies affecting their ecological safety. In this study, steroids, bisphenol A (BPA) and phthalates were assessed in the secondary (SE) and tertiary effluent (TE) of three typical urban STPs in Beijing (China). In addition, the overall estrogenic activity in these effluents was assessed by an in-vitro bioassay (ERE-CALUX). Results showed that the concentrations and activities of estrogenic compounds in TE were lower than those in SE. The residual concentration of 17β-estradiol (E2) was the highest among the detected steroids, accounting for 51.6 ± 5.1% in SE and 57.5 ± 24.8% in TE. The residual level (25.2–41.6 ng/L) of BPA in effluents was significantly higher than that of steroids (0.2–28.8 ng/L). The residual concentration of diethyl phthalate was the highest among the detected phthalates accounting for 47.1 ± 5.1% in SE and 37.6 ± 11.5% in TE. Steroids and BPA had a higher removal rate (83.5% and 96.7%) in secondary and tertiary treatment than phthalates (68.8% and 83.1%). The hydrophobic characteristics of these estrogenic compounds determined the removal mechanism. The removal of steroids, BPA, dimethyl phthalate and diethyl phthalate (LogKow= 1.61–4.15) mainly occurred through biodegradation in the water phase, while the removal of dibutyl phthalate, butylbenzyl phthalate and di(2-ethylhexyl) phthalate (LogKow= 4.27–7.50) mainly occurred in the solid phase after adsorption on and sedimentation of the suspended particulate matter. According to ERE-CALUX, the estrogenic activity in the final STP effluents was 3.2–45.6 ng E2-equivalents/L, which is higher than reported levels in the effluents of European STPs. Calculation of estrogenic equivalents by using substance specific chemical analysis indicated that the dominant contributor was E2 (56.4–88.4%), followed by 17α-ethinylestradiol (EE2) (4.1–34.8%), both also exerting a moderate risk to the aquatic ecosystem. While the upgrade of treatment processes in STPs has efficiently reduced the emission of estrogenic substances, their ecological risk was not yet phased out.

Application of biosolids in civil engineering: State of the art

Biosolids are the byproducts from the domestic/industrial sewage treatment processes, and contains solids and heavy metals. They are conventionally disposed by landfilling, ocean disposal, or incineration methods. However, owing to the cost of disposal and negative environmental impact, in recent years, efforts have been made by researchers to utilize biosolids for various applications. Many researchers have reported civil engineering applications of stabilized biosolids (lime / cement / crushed concrete stabilized biosolids) such as backfill material, fill for road embankment, brick and aggregate manufacturing. The studies have also reported that stabilized biosolids yields reduction in permeability, and improvement in shear strength, compaction characteristics (OMC and MDD) and California bearing ratio (CBR). This paper reviews in details the existing literature related to various aspects such as characterization of biosolids, its environmental impact and treatment/stabilization methods while emphasizing on its potential applications. The study concludes that stabilized biosolids have good potential to be utilized for various Civil Engineering applications, while minimizing the impact on environment and challenges related to disposal of biosolids.

ADSORPTION OF ACTIVE CHLORINE AND TECHNOLOGY OF AN AQUEOUS SOLUTION DECHLORINATION BY MODIFIED ACTIVATED CARBON

The influence of the modified activated carbon activation type on the degree of adsorption of active chlorine from the aqueous solution was studied. The influence of water flow rate and purification process duration on the adsorption of active chlorine by modified activated carbon was researched and the optimal parameters of the dechlorination regime were determined. The proposed method of extraction of active chlorine by modified activated coal obtained from peach shells can be used in natural and sewage treatment processes for the removal of the active chlorine and chlorine compounds. The design of the mass transfer apparatus with a fixed layer of adsorbent has been developed. The technology of dechlorination aqueous solution by modified activated carbon allows to increase the efficiency of purification up to 99%.

Study of the Characteristics of Pollutants in Rural Domestic Sewage and the Optimal Sewage Treatment Process: A Chengdu Plain Case Study

Study of the Characteristics of Pollutants in Rural Domestic Sewage and the Optimal Sewage Treatment Process: A Chengdu Plain Case Study

하수처리시설에서 공정별 황화수소와 복합악취 발생 특성 및 상관분석

Although sewage treatment plants play an important role in water purification, odors from the facilities are frequently a source of complaints, eliciting objections from both plant workers and neighbors. Hydrogen sulfide is a natural by-product of anaerobic digestion that has a strong, unpleasant odor. Therefore, many researchers in Korea have attempted to characterize odors emitted by sewage treatment plants in odor to reduce their emissions. However, these researches have primarily focused on odor intensity scales or the measurement of odor compounds in several sites without considering detailed information of the statistical analysis. In this study, using 75th percentile of unit processes as the complex odor, the operations connected with sludge thickening were discovered to be the main emission sources of odorous substances, followed by primary settling, equalization, anaerobic, dewatering, anoxic, preliminary treatment, and aerobic processes. These results will be aid in identifying major odor sources associated with sewage treatment processes and prioritizing an odor control plan. In this study, the possibility of predict complex odor from hydrogen sulfide concentrations was considered when performing correlation and regression analysis. It could be used to define the requirements for installing odor eliminators and establishing odor regulations in sewage treatment plants.

Analysis on the Treatment Process of Industrial Wastewater and Domestic Sewage

Analysis on the Treatment Process of Industrial Wastewater and Domestic Sewage

Integration of anammox into the MBR process for main stream sewage treatment

Abstract The integration of anaerobic ammonia oxidation (anammox) into the membrane bioreactor (MBR) process (AX-MBR) is proposed in this study to reduce operating costs. The temperature was not controlled during the study. Anammox, denitrification, and nitrification were studied in the AX-MBR for 210 days. The reactor was fed with mainstream sewage from Guilin City, China. The results showed that AX-MBR could run with reduced dissolved oxygen (DO) concentration, and COD, NH4+-N, and total nitrogen removal were maintained or improved. The microbial analysis results demonstrated that the added anammox sludge could survive in the AX-MBR, but the sludge microbial diversity decreased. Nitrospira, Candidatus Kuenenia, and Nitrosomonas dominated the anammox sludge. In a word, the AX-MBR developed in this study could treat mainstream sewage with the appropriate management, and the operation costs are expected to reduce by decreasing the amount of aeration.