Wastewater Flow Rate Research Articles

Low-Cost Device for Measuring Wastewater Flow Rate in Open Channels

This research paper describes the development of a low-cost device for measuring wastewater flow rates in open channels, a significant advancement enabled by the evolution of microcomputers and processing techniques. A laboratory setup was constructed to validate the device’s accuracy against a standard flow measurement method, optimizing key parameters to achieve a linear relationship between detected and set flow rates, while considering hardware limitations and energy efficiency. The central focus of the research was developing a method to measure the velocity of contaminated fluid using ultrasonic signals, employing the cross-correlation method for signal delay analysis in a stochastic environment. This was complemented by a procedure to measure fluid levels, also based on ultrasonic signals. The device’s reliability was assessed through repeatability and uncertainty measurements, confirming its accuracy with an extended uncertainty not exceeding an average of 3.47% for flows above 40 L/min. The device has potential to provide valuable data on the operational dynamics of sanitary networks, crucial for developing and calibrating simulation models.

Development of a novel energy efficient integrated system for concurrent waste water treatment, hydrogen production and carbon capture- A sustainable approach

Microbial Electrochemical Cells (MECs) technology offer a promising, integrated solution for wastewater treatment and hydrogen production. The present research aims to optimize the operation of a hybrid system for achieving high-efficiency wastewater treatment, carbon capture, and hydrogen production. Multi-criteria decision methods are used to identify optimal conditions for maximum performance. Wastewater Flow Rate (WFR), Energy Consumption (EC), Nanocomposites Concentration (NC), and Temperature (T) are chosen as input parameters. Utilizing the Entropy-TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) method, the optimal outputs were determined for specific input settings. The proposed system exhibited optimal input settings at 1100 m³/day (WFR), 95 kW (EC), 34 mg/L (NC), and 36 °C (T). NC emerged as the most influential parameter, holding a significance weightage of 32%, followed closely by temperature. Under these optimized conditions, the system demonstrated exceptional performance, achieving a Wastewater Treatment Efficiency of 98.1%, Carbon Capture Efficiency of 97%, and a Hydrogen production flow rate of 17.76 m³/hr. This research lays a foundation for sustainable and versatile wastewater management practices, emphasizing the potential of MEC systems in contributing to cleaner and resource-efficient industrial ecosystems.

Application of Membrane Bioreactor (MBR) for Antibiotic Elimination From Wastewater

In this study, a membrane bioreactor – MBR system at laboratory-scale was designed to remove sulfamethoxazole (SMX) in water. The system consists of a 8-liter aerobic tank combined with a hollow fiber micro filtration membrane (MF). Influent flow rate of wastewater was 15,84 L/day. Affecting factors to treatment efficiencies (organic pollutants and antibiotics) such as contact time and initial antibiotic concentration were investigated. Experimental results indicated that wastewater with initial parameters COD, NH4+, NO3-, PO43- were respectively 240, 9,4, 37,5, 6,3 mg/L, the treatment efficiencies achieved were respectively at 63,4, 89,7, 78,1, and 79,8%. The removal efficiencies of the wastewater containing SMX (concentrations range from 0,052 to 0,268 mg/L) for COD and NH4+ decreased by 4,2 and10,9% respectively, and for NO3- and PO43- increased by about 4,5 and 7,9%, correspondingly. Overall SMX elimination performance is about 49,7%.

Numerical investigation on mixing behaviour in the contact zone of an industrial‐scale dissolved air flotation tank

AbstractThe mixing behaviour of the wastewater and the recycle bubbly water in the contact zone could affect the separation performance of dissolved air flotation systems. In this study, the mixing characteristics in the contact zone of an industrial‐scale dissolved air flotation tank were investigated using the computational fluid dynamics method. At first, the influence of the turbulence model on the simulation results was clarified. It is demonstrated that the realizable k‐ε model could predict the gas holdup distribution with better accuracy, and the maximum relative deviation between the predicted gas holdup and the experimental results is only 10%. The influence of the geometry and operating parameters on the mixing process was then studied numerically. It is found that the mixing performance in the contact zone could be improved by decreasing the height position of the nozzle inlet in a certain range. The reason is that microbubbles disperse better in the bottom region and a double circulation flow state forms in the contact zone when the nozzle inlet is installed at a low height. Additionally, the mixing process could be further enhanced by decreasing the diameter of the nozzle inlet. As to the operating conditions, increasing the recycle ratio could not only increase the gas holdup but also improve the mixing performance in the contact zone. When the recycle flow rate remains constant, increasing the wastewater flow rate will lead to a decrease in gas holdup and deterioration of the mixing effect.

Optimal refrigerant selection and parameter analysis of a wastewater heat pump using CO2 zeotropic mixtures

Heat pump technology can effectively recover waste heat from low-grade wastewater, which is crucial for energy conservation and carbon emission reduction in buildings. In this study, zeotropic mixtures were used to recover heat from low-grade wastewater and produce high-temperature water in a heat pump. The deep recovery of waste heat was realized by using a CO2 zeotropic mixture with a large glide temperature. Furthermore, this method ensures an excellent temperature matching between the heat transfer fluids and effectively reduces irreversible losses. To obtain an optimal zeotropic mixture, a method based on heuristic screening of the optimal CO2 zeotropic mixture was proposed. Furthermore, a model of a CO2 zeotropic mixture heat pump was established and experimentally validated. Based on the validated model, a sensitivity analysis of the various operating parameters of the heat pump was conducted. The results show that the zeotropic mixture CO2/R1234yf with a mass fraction of 0.17/0.83 is selected as the optimal refrigerant for the heat pump with the coefficient of performance, exergy efficiency and volumetric heating capacity of 7.46, 0.37, and 7978 kJ⋅m−3, respectively. The sensitivity analysis of operating parameters shows that the inlet temperature of hot water has more crucial influence on the coefficient of performance and exergy efficiency than various operating parameters, with sensitivity coefficients of −0.3868 and 0.2157, respectively. The volumetric heating capacity and system total exergy destruction per heating capacity unit are most sensitive to the flow rate of wastewater and hot water, with sensitivity coefficients of 0.1121 and −0.4985, respectively. These results provide a foundation for the design and optimization of a CO2 zeotropic mixture heat pump system.

Treatment of cattle slaughterhouse wastewater by sequential coagulation-flocculation/electrooxidation process

This study aimed to investigate the applicability and efficiency of sequential coagulation-flocculation (CF) and electrooxidation (EO) processes for cattle slaughterhouse wastewater by evaluating treatment efficiency and total operating cost values together. The effect of two different coagulant dosages (FeCl3 and alum) in the CF process and operating parameters such as current density (5 to 30 mA/cm2), wastewater flow rate (0.9 to 3.6 L/h), and supporting electrolyte concentration (1 to 3 g NaCl/L) in the EO process on chemical oxygen demand (COD) and turbidity removal were investigated. During the first part of the study, the FeCl3 coagulant dosage worked better than other coagulants, eliminating 50% of the COD and 68% of the turbidity. Due to the insufficient removal efficiencies of COD and turbidity, a secondary treatment was required. In the second part of the study, a boron-doped diamond (BDD) electrode was used to treat the coagulated effluent in a continuous EO reactor. The COD and turbidity removal efficiency under optimum treatment conditions (j = 30 mA/cm2, Q = 0.9 L/h, pH = 8.5, SE = 3.0 g NaCl/L, and hydraulic retention time = 1 hour) were calculated as 97.2% and 99.9%, respectively. At these optimum conditions, the energy consumption and total operating cost were calculated as 91.1 kWh/m3 (73.5 kWh/kg COD) and 3.50 US $/m3 (1.5 US $/kg COD), respectively. As a result, combined coagulation-flocculation and electrooxidation processes have proven to be very successful and cost-efficient for treating cattle slaughterhouse wastewater.

Bone Char Adsorption of COD and Colour from Tannery Wastewater: Breakthrough Curve Analysis and Fixed Bed Dynamic Modelling

This study delves into the simultaneous adsorption of chemical oxygen demand (COD) and colour from tannery wastewater using bone char through a fixed bed column. The bone char, which was derived from cattle skulls, was characterised using the Fourier transform infrared spectroscopy, Braeuer–Emmett–Teller surface area analysis, and the scanning electron microscope/energy-dispersive X-ray spectroscopy. The effects of different process conditions, specifically, packed bed height (5, 10, and 15 cm) and flow rate (2, 5, and 8 mL/min), on the adsorption efficiency of the fixed bed column were assessed through breakthrough curve analysis. The results revealed that the efficiency of the column bed enhanced with increasing bed height and declined with increasing wastewater flow rate. The optimal operating conditions for COD and colour removal onto the bone char occurred at 15 cm bed height and 2 mL/min flow rate. The adsorption capacities at these conditions were 227.4 mg/g and 53.03 Pt-Co/g for COD and colour, respectively. The kinetics associated with the fixed bed adsorption of COD and colour onto bone char were elucidated through the fitting of the Thomas, Adams–Bohart, and Yoon–Nelson models to the experimental data. Among the three models, the Yoon–Nelson model gave the best prediction of the experimental data. Maximum adsorption efficiencies of 80.65% and 84% were attained for COD and colour removal, respectively, proving that bone char is a promising and ecologically friendly alternative adsorbent for the treatment of tannery wastewater.

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

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

Electrochemical treatment of plastic industry wastewaters powered by photovoltaic solar energy

Electrochemical processes combined with renewable energy sources are considered sustainable and efficient for wastewater treatment. The combined photovoltaic – electrochemical (PV-EC) method can produce electrolytic hydrogen and purify industrial wastewaters by combining solar energy with electrocoagulation and electrooxidation processes. The PV-EC system's adaptability resides in its capacity to modify wastewater flow rate in response to the PV array's current intensity and instantaneous solar radiation. Operating parameters that affect process efficiency include wastewater flowrate, applied current intensity, electroprocessing time and solar irradiance were examined and optimal conditions were identified. The experimental results revealed that the initial chemical oxygen demand (COD) of 19 460 mg L-1 of the plastic industry wastewater, were decreased to 8000 mg L-1, after 2 h electroprocessing time using iron or aluminium electrodes at 600 mA current intensity. Further increase of COD removal efficiency was not possible either with increasing processing time, current intensity or using electrooxidation process. The results of our study indicate that the electrochemical treatment can reduce COD from wastewater generated during the production of plastic products. Moreover, the proposed method is applicable in decentralized areas without access to the electricity grid.

Microplastics transfer from a malfunctioning municipal wastewater oxidation pond into a marine protected area in the Colombian Caribbean

Wastewater is an important source of microplastics (MPs) in aquatic ecosystems, threatening their biodiversity and environmental services. This study examines the contribution of MPs from the effluents of a municipal wastewater treatment pond system (WTS) to a stream that flows into the Cispata marine protected area (MPA) in the Colombian Caribbean. Samples of influent and effluent wastewater and sludge in the WTS were analyzed to determine the abundance and types of MPs. Additionally, the wastewater flow rate was measured using a volumetric method, and its MP load calculated. The abundance of MPs in the influent and effluent of the WTS was 15 and 5 items L–1 of wastewater, and 11 and 4 items Kg–1 dw of sludge, respectively. Fibers (67–75%) prevailed in the wastewater, while fragments (56–67%) were predominant in the sludge. Whereas the removal of MPs entering the WTS was 67%, the wastewater effluents still contribute approximately 1.3 million items day–1 to the stream flowing into the MPA. Our study highlights that a poorly functioning WTS causes substantial MP discharges into sensitive aquatic coastal ecosystems. These WTS require ongoing maintenance and improvements to ensure their long-term optimal operation and function of reducing pollutant loads and environmental risks in recipient aquatic ecosystems.

Methane Production from a Rendering Waste Covered Anaerobic Digester: Greenhouse Gas Reduction and Energy Production

Livestock wastes can serve as the feedstock for biogas production (mainly methane) that could be used as an alternative energy source. The green energy derived from animal wastes is considered to be carbon neutral and offsetting the emissions generated from fossil fuels. In this study, an evaluation of methane production from anaerobic digesters utilizing different livestock residues (e.g., poultry rendering wastewater and dairy manure) was carried out. An anaerobic continuous flow system (15 million gallons, polyethylene-covered) subjected to natural conditions (i.e., high flow rate, seasonal temperatures, etc.) containing poultry rendering wastewater was set up to evaluate methane potential and energy production. A parallel pilot-scale plug-flow anaerobic digestion system (9 m3) was also set up to test different feedstocks and operating parameters. Biogas production was sampled and monitored by gas chromatography over several months of operation. The results showed that methane production increased as the temperature increased as well as depending on the type of feedstock utilized. The covered rendering wastewater lagoon achieved an upward of 80% (v/v) methane production. The rates of methane production were 0.0478 g per g of COD for the poultry rendering wastewater and 0.0141 g per g of COD for dairy manure as feedstock. Hence, a poultry processing plant with a rendering wastewater flow rate of about 4.5 million liters per day has the potential to capture about two million kilograms of methane for energy production per year from a waste retention pond, potentially reducing global warming potential by about 50,000 tons of CO2 equivalent annually.

Energy yield from wastewater by supercritical water oxidation process: Experimental validation and simulation from the viewpoint of energy system

The degradation of high concentration organic wastewater and the recovery of energy using supercritical water oxidation (SCWO) technology have the potential to become viable in the future. High concentration organic wastewater contains a significant amount of energy. This paper focuses on utilizing high concentrated wastewater as a renewable energy source, from an energy system perspective, an experimental rig was designed to determine the optimal working conditions. The experiments were conducted with an oxidation coefficient of 1.1, a flow rate of high concentration organic wastewater of 9 ml/min, a heating temperature of 400 °C, and a reaction pressure of 25 MPa. Under these conditions, the COD and TOC removal rates of the high concentration organic wastewater were found to be 99.383 % and 99.876 % respectively. Additionally, the phenomenon of “Abnormalities in pressure sensitivity” observed during high concentration organic wastewater the experiment was further explained through additional experiments. Finally, by comparing the experimental energy recovery with the simulation results, an energy recovery efficiency of 78.95 % was achieved. The feasibility of the simulated energy recovery in practice was verified, confirming the potential to convert the previous energy-consuming wastewater treatment process into a productive one. This study provides a theoretical and experimental foundation for further related research.

A new evaluation framework for the assessment of wastewater heat recovery potential coupled with wastewater reuse

Abstract The integration of wastewater heat recovery (WWHR) and wastewater reuse offers a numerous advantage, making its application possible in various sectors. Nevertheless, this concept faced challenges to the identification of appropriate location. Existing research lacks comprehensive evaluation methods that encompass a various factor for effective decision-making. This study introduces a new evaluation framework that involves different aspects, including thermal energy potential and spatial distribution analysis. The novelty of this research lies in its unique focus on the combination of WWHR and wastewater reuse. Moreover, it introduces a structured evaluation framework that considers multiple criteria and expert opinions, enhancing decision-making precision. Multi-criteria decision analysis (MCDA) was applied to select assessment criteria, which were categorized into three aspects: water–energy supplier, water–energy consumers, and water–energy station. The relative importance of criteria was determined using the analytical hierarchical process (AHP). The results of the AHP highlight significance of factors: treated wastewater flow rate; treated wastewater temperature; water–energy supply distance, and type of water–energy consumer. These factors were assigned weight values of 0.297, 0.186, 0.123, and 0.096, respectively. It is emphasizing their influence in the decision-making process that potential locations depend on the water–energy supplier and water–energy consumer as supply and demand sources.

Dynamic-chance-constrained-based Fuzzy Programming Approach for Optimizing Wastewater Facultative Ponds for Multi-period Case

In this article, a novel optimization model that was specifically designed as a dynamic-chance-constrained fuzzy uncertain programming framework is introduced. This model serves the purpose of optimizing the efficiency of facultative ponds utilized in domestic wastewater treatment. The primary focus of this study was maximizing the amount of the wastewater treated in the facility subject to quality requirements via the assessment of wastewater quality through the measurement of Biological Oxygen Demand (BOD). The model's development was grounded in a real-world scenario, where decision-makers encountered uncertainties in various parameters, such as the rate of BOD degradation and the incoming wastewater load, both characterized by fuzzy membership functions. In light of this uncertainty, the decision-maker aimed to maximize the wastewater treatment capacity while maintaining a suitable safety margin for both objective and constraint functions, employing policies founded on probability and chance. A case study was carried out at the Bantul domestic wastewater treatment plant, situated in Yogyakarta, Indonesia. The study successfully identified optimal decisions regarding wastewater flow rates and processing times. As a result, it can be concluded that the proposed model effectively resolved the problem at hand, making it a valuable tool for decision-makers in similar contexts.

Evaluation of four human-associated fecal biomarkers in wastewater in Southern Ontario

Human fecal biomarkers (HFBs) have a longstanding history in the field of microbial source tracking (MST) serving as indicators of human fecal contamination in drinking and recreational water. Further, HFBs have aided in recent efforts to monitor human pathogen transmission within communities. The dilution of wastewater from various sources throughout the sewershed cannot be controlled and human fecal biomarkers (HFBs) can be used to normalize target human pathogen concentrations so that fluctuations in fecal matter in wastewater can be accounted for. In the current study, we monitored the prevalence of four HFBs – including two viruses, Pepper mild mottle virus (PMMoV), cross-assembly phage (crAssphage), as well as two human-associated Bacteroides markers, HF183 and BacHuman - in wastewater samples from ten Southern Ontario wastewater treatment plants and evaluated their temporal and spatial variation in context of environmental factors that may impact the ability of HFB to normalize pathogen concentrations in wastewater. Environmental variables including precipitation, wastewater flow rate, temperature, and concentrated mass were also analyzed for their potential correlation with HFB variation in wastewater. The four HFBs were detected at high concentrations across all 10 sampling locations. The median concentrations across all sampling sites were: PMMoV 3.6 Log gene copies (GC)/mL; crAssphage 5.0 Log GC/mL; HF183 6.8 Log GC/mL and BacHuman 6.9 Log GC/mL. All HFBs were found to be similarly stratified across all 10 sites, and the bacterial markers were consistently found at higher concentration compared to the viral HFBs at all sites. The coefficient of variation (CV) for each HFB was used to characterize the variability of each biomarker at each sewershed. BacHuman and crAssphage were found to have lower CV than PMMoV and HF183, indicating that BacHuman and crAssphage may perform better in reflecting the variations in abundance of human feces in wastewater or MST applications.

Are algae a promising ecofriendly approach to micro/nanoplastic remediation?

How to reduce microplastic pollution in aquatic ecosystem has become the focus of the global attention. The re-removal of microplastics of wastewater treatment plant (WWTP) effluent is gradually being put on the agenda. Recently, algae have been used as an ecofriendly remediation strategy for microplastic removal. Microplastics in sewage can be removed by algae through interception, capture, and entanglement, and can also form heterogeneous aggregates with algae, thereby reducing their free suspensions. Algae can recover nitrogen and carbon from wastewater and can be made into biochar, biofertilizers, and biofuels. However, problematically, this technology has been in the laboratory research stage, and existing research results cannot provide effective basis for its application. Microplastic removal via algae is influenced by wastewater flow rate, microplastic types, and pollutants. Microplastics are only physically fixed by algae, and ensuring that microplastics do not re-enter the environment during resource and capacity recovery is also a key factor limiting the implementation of this technology. The topic of this paper is to discuss the performance of the current tertiary wastewater treatment process - algae process to remove microplastics. Algae can remove nitrogen and phosphorus pollutants in sewage and remove microplastics at the same time, which can realize energy recovery and reduce ecological risks of the effluent. Although algae combined tertiary sewage treatment is a green technology for microplastic removal, its application still needs to be explored. The key challenges that need to be addressed, from single laboratory conditions to complex conditions, from small-scale testing to large-scale simulations, lie ahead of the application of this friendly technology.

Study of Septic Tank Wastewater Distribution in Soil

In general, people use septic tanks for household wastewater management, but most of them do not meet health requirements and sni regulations, resulting in polluted shallow groundwater. Because of these issues, the author conducted a laboratory simulation of septic tank wastewater seepage on a small scale. This research was carried out in a 100 cm x 100 cm x 40 cm glass box. The aim of this study was to determine the distribution distance, flow rate, and travel time of septic tank wastewater in a horizontal direction wihtin a glass container. The study used statistical analysis to examine the horizontal spread of septic tank effluent in a glass box. The distribution simulation was performed using laboratory tests a ratio 1:10 according to the existing conditions and soil physical properties were tested. Contaminant parameters including the concentration of Escherichia coli and ammonia (NH3N) were analyzed based on distance and time. The number of samples tested in this study was 40 arranged transversely. The results of soil physical property tests included specific gravity of 2,648%, plastic limit of 16,443%, liquid limit of 25,906%, plastic index of 9,463%, sieve analysis of 17,51%, moisture content of 13%, organic matter of 6,12% and permeability 5,388 x 10−5 cm/s. The results of Escherichia coli concentration tests at showed that the concentration was 1,6 x 104 (mpn/100 ml) at the closets distance from the source of spread and 0,92 x 104 (mpn/100 ml) at the farthest distance. The ammonia (nh3n) concentration at the closest distance from the source of spread was 1,30 (mg/l) and the farthest distance was 0,97 (mg/l). The simulation results of the horizontal spread of septic tank wastewater in a glass box at a distance 81 cm required a travel time of 425 minutes (7 hours 5 minutes) with a septic tank wastewater spread speed/flow rate 8,4 x 10−5 liter/minute.

A powerful strategy to improve aerobic granular sludge stability towards organic shock loadings with varying carbon/nitrogen ratios: Weak magnetic field

The organic shock loadings with varying ratios of carbon to nitrogen (C/N) caused by fluctuations of wastewater flowrate and concentration inflict a great threat on the stability of aerobic granular sludge (AGS) in practical applications. Herein, the present work proposed an enhanced shock-loading-tolerance strategy for AGS by applying a weak magnetic field (WMF). Results indicated that aerobic granules exposed in WMF kept a significant propagation regardless of the various influent organic concentrations, while those in the control reactor exhibited inadaptability with decreasing biomass concentration and bioactivity at lean substrate conditions. The enhanced extracellular polymeric substances regulating process might be one of the inducement mechanisms to cope with organic shock loadings of WMF. In addition, the AGS system in WMF showed its strong resilience in terms of the ammonia and phosphate removal. Magnetic field could inhibit the overgrowth of filamentous bacteria, and the enhanced tolerance for organic shock loadings might attribute to the enrichment of functional microbes related to structural stability such as Firmicutes and Candidatus_Competibacter. Therefore, this work revealed the enhanced mechanisms of magnetic field for improving the AGS stability towards organic shock loadings, promoting the full-scale engineering applications of both AGS and magnetization technologies in wastewater treatment.

Which Configuration of Photocatalytic Membrane Reactors Has a Major Potential to Be Used at an Industrial Level in Tertiary Sewage Wastewater Treatment?

Photocatalytic membrane reactors (PMRs) have been found to be very effective in the removal of organic pollutants (particularly recalcitrant compounds) from wastewater because they allow for the mineralization of organic pollutants to innocuous by-products, thus achieving high-quality treated water. Owing to the very high volumes of water involved, treated sewage wastewater could be reused if a very efficient tertiary stage, like a PMR, can be foreseen. In this review, the two main PMR configurations (photocatalytic membranes and slurry PMRs) were analyzed as requirements of a tertiary treatment of sewage wastewater considering six design and operational parameters of such plants: (i) continuous wastewater flow rate from the secondary stage; (ii) the self-control of the photodegradation rate related to wastewater chemical–physical parameters; (iii) ability to handle variations of wastewater concentration and flow rate; (iv) the control of the quality of treated wastewater; (v) low plant footprint; and (vi) easy maintenance. In this analysis, some characteristics of photocatalysis (which involves three phases: solid (the photocatalyst), liquid (the wastewater), and gas (oxygen or air)) and those of membranes (they can be produced using different materials and configurations, different processes (pressure-driven or not pressure-driven), etc.) were considered. The obtained results show that slurry PMRs seem more suitable than photocatalytic membranes for such applications. We believe this review can trigger a shift in research from the laboratory to industry in using photocatalytic membrane reactors.

Response of a novel denitrifying phosphorus removal (AAO-BCO) system to sinusoidal flow perturbation of municipal sewage: Adaptability, tolerance and improvement

To date, studies on the effect of sewage disturbances on treatment facilities were based on fixed-length flow variations, which are incapable of imitating the actual dynamic flow characteristics of municipal sewage. Here, an innovative dynamic influent disturbance control system is established in this study and applied in a novel denitrifying phosphorus removal (anaerobic anoxic oxic-biological contact oxidation, AAO-BCO) system to simulate seasonal and diurnal sewage fluctuations in laboratory-scale experiments. The results showed that, under sinusoidal influent flow perturbation, the effluent pollutant content followed a relatively gentle sinusoidal trend and did not always result in desired level of pollutant removal. The ability of the system to cope with sinusoidal flow variations was susceptible to the amplitude of diurnal sewage fluctuation, while stronger tolerance capacity was observed to seasonal and momentary increase in wastewater flowrate. There was also a discrepancy in the system buffering capacity towards various pollutants removal (COD > TIN > PO43−), which may be attributed to wide fluctuations in PO43−/NO3− and different decrease in metabolic activity of denitrifying phosphorus removal (DPR) sludge caused by extreme hydraulic retention times. To improve the robustness and stability of the DPR system, a regulating strategy was proposed to alleviate the biomass reduction and uncoordinated PO43−/NO3−.