Odors due to the emission of hydrogen sulfide (H
S) have been a concern in the sewage treatment plants over the last decades. H
S fate and emissions from extended aeration activated sludge (EAAS) ...system in Muharram Aisha-sewage treatment plant (MA-STP) were studied using TOXCHEM model. Sensitivity analysis at different aeration flowrate, H
S loading rate, wastewater pH, wastewater temperature and wind speed were studied. The predicted data were validated against actual results, where all the data were validated within the limits, and the statistical evaluation of normalized mean square error (NMSE), geometric variance (VG), and correlation coefficient (R) were close to the ideal fit. The results showed that the major processes occurring in the system were degradation and emission. During summer (27 °C) and winter (12 °C), about 25 and 23%, 1 and 2%, 2 and 2%, and 72 and 73% were fated as emitted to air, discharged with effluent, sorbed to sludge, and biodegraded, respectively. At summer and winter, the total emitted concentrations of H
S were 6.403 and 5.614 ppm, respectively. The sensitivity results indicated that aeration flowrate, H
S loading rate and wastewater pH highly influenced the emission and degradation of H
S processes compared to wastewater temperature and wind speed. To conclude, TOXCHEM model successfully predicted the H
S fate and emissions in EAAS system.
The novel process consisted of two steps was established by combining all sidestreams lines (supernatant gravity thickener, underflow mechanical thickener, and centrate), treating them together away ...from the mainstream treatment plant, and returning treated sidestreams effluents to the plant outfall instead of plant head. The two steps novelty treatment combined degradation, nitrification, and dilution processes. To treat combined sidestreams, a novel pilot extended nutrient moving bed biofilm reactor was developed. The effects of sidestream elimination on a full-scale anaerobic/anoxic/oxic system were simulated using GPS-X7. The statistical results of R values greater than 0.8 and NMSE values near zero proved the calibrated model's validation. The novel system successfully removed 98, 93, 100, 85, 98, 100, and 98% of BOD, COD, NH
, NO
, TSS, H
S, and PO
-P from sidestreams, respectively. Furthermore, the simulation results showed that eliminating sidestreams has reduced volumes of full-scale A
/O facilities, controlled hydraulic and pollutants shocks, and minimized cost and energy. The novel process proved successful in treating combined sidestreams and eliminating their impacts on the A/O
system.
This review examines a variety of adsorbents and discusses mechanisms, modification methods, recovery and regeneration, and commercial applications. A summary of available researches has been ...composed by a wide range of potentially low-cost modified adsorbents including activated carbon, natural source adsorbents (clay, bentonite, zeolite, etc.), biosorbents (black gram husk, sugar-beet pectin gels, citrus peels, banana and orange peels, carrot residues, cassava waste, algae, algal, marine green macroalgae, etc.), and byproduct adsorbents (sawdust, lignin, rice husk, rice husk ash, coal fly ash, etc.). From the literature survey, different adsorbents were compared in terms of Zn2+ adsorption capacity; also Zn2+ adsorption capacity was compared with other metals adsorption. Thus, some of the highest adsorption capacities reported for Zn2+ are 168 mg/g powdered waste sludge, 128.8 mg/g dried marine green macroalgae, 73.2 mg/g lignin, 55.82 mg/g cassava waste, and 52.91 mg/g bentonite. Furthermore, modification of adsorbents can improve adsorption capacity. Regeneration cost is important, but if consumption of virgin adsorbent is reduced, then multiple economic, industrial, and environmental benefits can be gained. Finally, the main drawback of the already published Zn2+ adsorption researches is that their use is still in the laboratory stage mostly without scale-up, pilot studies, or commercialization.
This paper describes the application of the storm water management model (SWMM) for predicting the sewage quality in the sanitary sewer system of the study area resulting from the leaking of ...stormwater surface runoff to the system during rainfall events at different return periods. The concentrations of major pollutants were assessed in the sanitary sewer system at different rainfall intensities. Then, a solution to mitigate the problem was proposed using low impact development (LID) technology. The results of sensitivity analysis indicated that maximum build-up possible was the most sensitive parameter for model calibration. The model was calibrated using actual rainfall events, and statistical validation coefficients of R (0.81–0.82) and NMSE (0.0173–0.022) proved that the model is valid. The sewage quality assessment results showed that pollutants concentration increased to its maximum level at 20 min and gradually decreased to a slightly constant minimum value after 2 h. The proposed solution of LID reduced the pollutants concentrations by 82–88, 75–77, 52–55, and 7–10% for all pollutants at return periods of 2, 5, 10, and 25 years, respectively. To conclude, SWMM simulation successfully predicted the concentration of the pollutants, and leaking of stormwater surface runoff has changed the sewage quality. HIGHLIGHTS Storm water management model (SWMM) simulated the leaking of stormwater surface runoff into the sanitary sewer system.; Sewage quality in the sewer system highly influenced by stormwater surface runoff leaking.; Low impact development (LID) strategies have been applied to mitigate stormwater surface runoff leaking.; An important information on stormwater and sewage management for decision makers, sanitary experts, and stockholders has been provided.;
This study examined >140 relevant publications from the last few years (2018–2021). In this study, classification was reviewed depending on the operation's progress. Electrocoagulation (EC), ...electrooxidation (EO), electroflotation (EF), electrodialysis (ED), and electro-Fenton (EFN) processes have received considerable attention. The type of action (individual or hybrid) for each electrochemical procedure was evaluated, and statistical analysis was performed to compare them as a new manner of reviewing cited papers providing a massive amount of information efficiently to the readers. Individual or hybrid operation progress of the electrochemical techniques is critical issues. Their design, operation, and maintenance costs vary depending on the in-situ conditions, as evidenced by surveyed articles and statistical analyses. This work also examines the variables affecting the elimination efficacy, such as the applied current, reaction time, pH, type of electrolyte, initial pollutant concentration, and energy consumption. In addition, owing to its efficacy in removing toxins, the hybrid activity showed a good percentage among the studies reviewed. The promise of each wastewater treatment technology depends on the type of contamination. In some cases, EO requires additives to oxidise the pollutants. EF and EFN eliminated lightweight organic pollutants. ED has been used to treat saline water. Compared to other methods, EC has been extensively employed to remove a wide variety of contaminants.
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•New insights and perspectives of electrochemical processes (EPs) for wastewater treatment are presented.•Various individual and hybrid operation progress electrochemical techniques are evaluated and compared.•Benefits and limitations to application of EPs for wastewater treatment are discussed.•Future research directions for developments and applications of EPs are highlighted.
Among countless applications, chitosan has the potential to be an effective and cheap adsorbent for pollutant removal in (waste) water. In form of beads, it also exhibits good mechanical and fluid ...dynamic properties that are suitable for utilization in large-scale adsorption processes (e.g. as column packing). The present study investigates the beading process to prepare chitosan and cross-linked chitosan beads by phase inversion method. Beading parameters (i.e. chitosan amount, acid concentration, non-solvent agent concentration, and temperature) are optimized to obtain an appropriate adsorbent structure to uptake large organic molecules (reactive red 2, a dye, is utilized as model pollutant). Chitosan beads present remarkably enhanced adsorption capacity, mainly thanks to increased specific surface area and porosity. The addition of a cross-linker (diepoxyoctane) further improves pollutant removal. The adsorption process is well-fitted by the Freundlich model, suggesting a multilayer adsorption. The kinetic study also substantiates the complexity of the adsorption mechanism on bead surface, which, however, is satisfactorily predicted by a simple fractal kinetic model. Finally, it is proved that chitosan and cross-linked chitosan beads can be recycled (by washing with NaOH solution) at least 5 times before sensible performance loss.
Earth dams are built for various reasons these including storage of water, regulation of water flow, prevention of flooding, and the generation of hydroelectric power. The drain pipes within an earth ...dam, are considered one of the more important control devices used to reduce the effects of problems caused by seepage. As such, the role of drain pipes against seepage problems in an earth dam, has been studied numerically in this investigation. The effects of drain pipe location and their diameters (50, 75, 100, and 150 mm), were examined using different hydraulic heads. The analysis focuses on the characteristics of relative seepage flow, exit gradient, and factor of safety regarding sliding. A range of models of typical earth dams, with and without drain pipes, have been simulated using Geo-Studio software in SEEP/W and SLOPE/W applications, examining more than 200 different cases. By using the data computed from numerical models, new formulas for predicting the seepage parameters and factors of safety were developed in this study by using the multiple non-linear regression (NLR) approaches. The findings show that the presence of a drain pipe reduces seepage flow and the exit gradient, at the same time increasing the factor of safety. Regarding pipe diameter, the rate of seepage and exit gradient decreased while the factor of safety increased as the diameter of the pipe increased. The factor of safety increased by between 11 and 25% when the drain pipe was placed in an optimal position, allowing for a reduction in seepage flow and exit gradient.
Global warming and unpredictable nature possess a negative impact on fisheries and the daily activities of other habitats. GIS and remote sensing approach is an effective tool to determine the ...morphological characteristics of the lake. The present study addresses the interactive effect of climate and landuse changes hit on fish catch in lake fisheries. We used a combination of the landscape disturbance index, vulnerability index, and loss index to construct a complete ecological risk assessment framework based on the landscape structure of regional ecosystems. The results indicate an increase from around 45%–76% in the percentage of land susceptible to moderate to ecological severe risk in the landscape from 2004 to 2023. Since 1950, temperature changes have increased by 0.4%, precipitation has decreased by 6%, and water levels have decreased by 4.2%, based on the results. The results indicate that landuse, water temperature, precipitation, and water depth significantly impact the aquaculture system. The findings strongly suggest integrating possible consequences of environmental change on fish yield for governance modeling techniques to minimize their effects.
•Appraisal of the combined effect of hydrometeorology and landuse change on lake fisheries.•Analyze the characteristics of lake morphometric indices.•Identify the dynamic ecological risk at the landscape level through the PLUS Model.•To establish a correlation between surface morphological features with susceptibility to the overland flows.•Areal fluctuations are calculated for 20 years.
A Genetic Algorithm technique, linked with a numerical solver model (Finite Elements) (GA-FEM), has been evolved to compute the optimal hydraulic design for a safe hydraulic structure to handle ...seepage concerns. The minimum cost of construction was considered the objective function during the formulation of the optimization process. While the major constraints were represented by the uplift pressure beneath the base floor and the exit gradient of seepage flow. The GA-FEM approach proposed in this study addresses the criteria of optimal hydraulic design in two main steps. First, the seepage problem was analyzed using a verified numerical model coded in finite-element programming. Then the Genetic Algorithm technique is used to address the optimal solution model and obtain the optimum (minimum construction costs) location and depth for the cut-offs under hydraulic structures. As a simulation/optimization (S–O) model, MATLAB platform code was utilized to construct a connection between the FEM and the optimization technique. The results refer to the developed GA-FEM model that can yield efficient, economical, and safe hydraulic designs for the cut-offs. The assessment of the GA-FEM proposed model indicated a good agreement between the simulation and expected results for seepage characteristics under the hydraulic structure.
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