The main objective of this research is an examination of the applicability of the QUAL2K mathematical model on large rivers like the Euphrates, and it is the first study of its kind conducted on this ...important section within Fallujah Euphrates Reach (FER), using this model for the purpose of evaluating the quality of water and creating a database to predict the quality of river. The tests were conducted during January and April of 2022, where they were calibrated and verified for DO and CBOD5 at a distance of 12.86 km. Google Earth pro and Arc-GIS were utilized to provide certain data as input into the QUAL2K model. The model was calibrated in January using the trial-and-error technique, and the verification was completed in April using the model calibration parameters. For the purposes of evaluating the model's performance, statistical measures such as mean absolute error (MAE), root mean square error (RMSE), and relative error (RE) were used. In addition, three different scenarios were applied (pollution load modification, flow augmentation for point sources, and flow augmentation for headwater) to improve the water quality of Euphrates river. The results show that the difference between observed and anticipated values had a relatively small error percentage, which means that this mathematical model can be applied to this important section of the river. While the concentration of DO was within the permissible limits to perpetuate aquatic life and maintain the ecological health of the river, the concentration of CBOD5 was also within the limits in some locations. In addition, the scenario represented by modifying the pollution loads represented by BOD5 for sewage water were effective in raising the concentration of DO in the river, while increasing point sources discharge and headwater flow does not yield meaningful results.
•Pilot treated raw wastewater at variable flow rate and ambient temperature for 500 days.•HRAS pilot plant was stabilized at extremely low SRT (< 0.5 d) and HRT (< 1 h).•HRAS harvested 60% of the COD ...in front the 35–40% of primary clarifiers.•Biomass monitoring was a successful strategy to control HRAS process stability.•Pilot plant HRAS performance was validated with a SUMO simulations.
In high-rate activated sludge (HRAS) processes, reducing the solid retention time (SRT) minimizes COD oxidation and allows to obtain the maximum energy recovery. The aim of this research was to operate a pilot plant with an automatic control strategy to assure the HRAS process stability and high COD fractions removal at very low SRT. This study combines simulation and experimental tools (pilot plant 35 m3·d − 1) operating at SRT (0.2 d), HRT (0.6 h) and DO (0.5 mg·L − 1) treating high-strength raw wastewater, at 18–26°C, at variable flow. The research includes the effects of temperature, influent concentration and MLSS reactor concentration over the sCOD, cCOD and pCOD removal.
The study points out that the best parameter to control the HRAS at a low SRT is not strictly the SRT but rather the reactor MLSS concentration: operating at 2,000±200mg·L − 1 assured a stable process despite the large influents variation. Low SVI values of 50–70ml·g − 1 indicated the good settling properties of the biomass. With only a 6.9% COD oxidation, a high organic matter removal (57±9% for COD and 56±10% for BOD5), was reached. The high removal efficiencies for pCOD (74%) compared to the (29%) for sCOD and (12%) for cCOD also confirmed the importance of settling efficiency and stability in the HRAS. The direct correlation between COD influent and COD removal makes advisable to use the HRAS as a replacement of the primary clarifier. The HRAS acted efficiently as a filter for COD and pCOD peak loads and, in a lesser extent, for BOD5, while sCOD peaks were not buffered. The adopted model presented a good fit for COD fractions except for pCOD when the temperature exceeds 23 °C.
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•Bacteria > archaea > eukaryote in richness and diversity.•Microbiome significantly (p < 0.05) differed at least two phases.•Microbiome structures were pH and BOD5 dependent ...pattern.•Abundant Ciliophora in MP suggested a short food chain establishment.•Acetoclastic and hydrogenotrophic methanogenesis were inhibited in ACP.
Bacterial, archaeal, and eukaryotic community composition and dynamics in leachate during solid waste decomposition were investigated using Illumina MiSeq sequencing. The functional enzyme-encoding genes of methanogenic pathways were also predicted via PICRUSt. Succession of bacterial, archaeal, and eukaryotic community composition in aerobic phase (AP), anaerobic acid phase (ACP), and methanogenic phase (MP) was observed. The main representatives of microbial phyla, genera, and species significantly (p < 0.05) differed at least two phases. Protist Ciliophora occurred at ACP and was prevalent in MP, suggesting a short food chain establishment in the methanogenesis. Bacterial, archaeal, fungi and eukaryotic community structure were all pH and biochemical oxygen demand (BOD5) dependent patter. Acetoclastic and hydrogenotrophic methanogenesis pathways with associated functional genes differed during solid waste decomposition and were inhibited in ACP.
•Vinasse physicochemical characteristics from a mexican native beverage makes it an ideal medium for anaerobic digestion.•Biodegradability index of vinasse indicates that treated anaerobically.•An ...extra microorganisms bed inside a UASB reactor improves the proportion of methane in biogas produced.
This work evaluated the redesign of an Upflow Anaerobic Sludge Blanket (UASB) bioreactor to increase biogas production from anaerobic digestion of vinasse and compared the redesign UASB bioreactor with a conventional UASB design. Vinasse contains a high level of organic matter, 120.2±18.4gO2/L of chemical organic demand (COD), and a 0.8 biodegradability index (BI). Thus, vinasse is a potential nutrient source for biogas production by anaerobic digestion. The modified UASB bioreactor has an innovation that consisted in a second leach bed sludge, which improved the methane proportion in biogas producing 2140mLCH4/day as compared to the traditional bioreactor (1840mLCH4/day).
Urban wastewaters from Kenitra had been discharged without prior treatment through six collectors into the Sebou estuary (60 km) causing in the process health and environmental problems up until WWTP ...was installed in 2020. The waste water treatment plant (WWTP) had to gather all urban wastewaters in order to go through treatment. Thus, the WWTP, situated 17 km from the mouth of the estuary, has become the only discharge point for treated domestic wastewater into the Sebou estuary. This study aims to model the Sebou estuary water quality and assessment of the impact of WWTP. Our study started with hydraulic modelling of the river using a 1D model (HECRAS 5.0.6), since water quality is strongly depending on hydraulic regime. HEC RAS has been calibrated and validated using hydraulic and morphological database of the years 2019 and 2021. The spatiotemporal evolution of hydraulic variables (water velocity, water level, etc.) was calculated by the hydraulic model and used in the water quality module to simulate the biochemical oxygen demand (BOD5). Two scenarios were put under examination, one is a simulation of discharges of untreated wastewaters by six collectors (mean BOD5 of 300 mg/L) and the second is a simulation of discharge after treatment at the WWTP (mean BOD5 of 24 mg/L). The simulation showed an impact of the tidal cycle and fresh water flows (coming from the upstream) on the urban wastewater discharges fate. Calculations of the BOD5 provided by the model are in good agreement with field measurements. The first simulation results show that water quality of the Sebou River does not meet WHO standards (average quality about 7 mg/l of BOD5). The second simulation shows that the treatment plant reduces the concentration of BOD5 in the river to about 3mg/l compared to the case before their installation, the quality of the water in the estuary is changing to become good after having been just average. In addition, the BOD5 concentration downstream of the WWTP changes according to the tidal cycle. Finally, the results show the very positive impact of Kenitra’s WWTP on the water quality of the Sebou River estuary.
Our previous reports have documented a single-step algal process for removing biochemical oxygen demand (BOD5) and nutrients from primary effluent in batch mode. In the current study, we report ...results from continuous fed-batch operation of this algal system demonstrating consistent removal of BOD5 and nutrients as well as significant reduction of pathogenic bacteria from primary effluent. The active volume of the algal bioreactor under fed-batch operation was 700 L, of which, 400 L was discharged at the end of every cycle and replenished with fresh primary effluent to start a new cycle. Results from thirty such cycles run over 120 days, under varying influent loadings and ambient conditions, confirmed that the discharge standards for BOD5 and nutrients could be attained in a fed-batch cycle time of <3 days. Typical volumetric removal rates of BOD5, ammoniacal nitrogen and phosphates over the 120 days were 16.5 mg/L-d, 6.1 mg/L-d, and 1.4 mg/L-d, respectively. Fecal and total coliform were also reduced to non-detectable levels within these three days.
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•Demonstrated stable algal wastewater treatment system in fed-batch mode•Demonstrated higher volumetric removal rates in fed-batch mode than in batch mode•Discharge standards met in 3 days fed-batch cycles in single step•Demonstrated simultaneous reduction of pathogenic bacteria
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•Demonstration of a new, fast and simple assay to assess microbial activity in water.•The assay predicts microbial activity and was strongly correlated with BOD5 and micro particle ...numbers 1–30 μm.•Potential applications of the method are discussed with emphasis on aquaculture.•The proposed assay can provide new important information of microbial water conditions, swift and simple.
This study proposes a new and simple assay that allows rapid assessment of microbial activity in water samples. The assay consists of standardized hydrogen peroxide (H2O2) addition to a water sample and subsequent spectrophotometric determination of H2O2 reduction over time. The H2O2 decomposition rate constant reflects the level of enzymatic activity from planktonic and particle-associated bacteria as well as algae and protozoans. The proof of concept was verified on water samples from recirculating aquaculture systems (RAS), showing that the vast majority of H2O2 decomposition was related to microbial activity. Only 3% of the total H2O2 decomposition was related to abiotic processes when 0.20 μm sterile filtered RAS water was compared with unfiltered RAS water. Planktonic bacteria (size range 0.20–1.6 μm) accounted for 16% of H2O2 decomposition, while bacterial aggregates, particle-associated bacteria and microbiota above 1.6 μm were responsible for the remaining 81%. H2O2 decomposition rate constants were positively correlated to BOD5 (r = 0.893; p < 0.001; n = 18) and to the number of 1–30 μm micro particles (r = 0.909; p < 0.001; n = 72) in RAS water, substantiating the biologically mediated decomposition processes in the water phase. The H2O2 decomposition assay thus represents a new alternative to existing methods that allows rapid (1–2 h) and simple quantification of microbial activity in fresh- and saltwater samples from aquaculture systems. Potential applications of the assay are discussed.
The domestic usage of water generates approximately 310 km3 of wastewater worldwide (2015, AQUASTAT, Food and Agriculture Organization of United Nations). This sewage contains an important organic ...load due to the use of this water; this organic load is characterized using a standard method, namely, the biological oxygen demand measurement (BOD5). The BOD5 provides information about the biodegradable organic load (standard ISO 5815). However, this measurement protocol is very time-consuming (5 days) and may produce variability in approximately 20% of results mainly due to variation in the environmental inocula.
To remedy these limitations, this work proposes an innovative concept relying on the implementation of a set of rigorously selected bacterial strains. This publication depicts the different steps used in this study, from bio-indicator selection to validation with real wastewater samples. The results obtained in the final step show a strong correlation between the developed approach and the reference method (ISO 5815) with a correlation rate of approximately 0.9. In addition, the optimization of the experimental conditions and the use of controlled strains (8 selected strains) allow significant reduction in the duration of the BOD5 analysis, with only 3 h required for the proposed method versus 5 days for the reference method. This technological breakthrough should simplify the monitoring of wastewater treatment plants and provide quicker, easier and more coherent control in terms of the treatment time.
•BOD5 assessment method requiring only 3 h (5 days with the reference method).•Approach based on 8 bacterial strains coupled with a processing by neural network.•Strong correlation between the new method results and reference data (r2 = 0.85).•Overall strategy, from the selection of strains to the validation on real samples.
Trong chế biến thủy sản, nước thải sơ chế tôm chứa nhiều nitrogen dưới dạng ammonium, nitrite và nitrate. Hàm lượng nitrogen còn thừa trong nước thải là nguyên nhân gia tăng các hợp chất có hại cho ...thủy sản. Nghiên cứu đánh giá hiệu quả xử lý nước thải sơ chế tôm được tiến hành trên hai mô hình xử lý nước thải IFAS: mô hình có chủng vi khuẩn nitrate hóa Pseudomonas aeruginosa ĐTW3.2 và mô hình đối chứng không chủng vi khuẩn. Với nước thải trước xử lý có nồng độ COD trong khoảng 754,93 ± 94,69 mg/L; BOD5 584,67 ± 17,17 mg/L và N-NH4+ 16,5 ± 1,24 mg/L thì mô hình IFAS có chủng dòng vi khuẩn nitrate hóa Pseudomonas aeruginosa ĐTW3.2 đạt hiệu suất xử lý COD; BOD5 và N-NH4+ lần lượt là 95,18%; 96,78% và 96,2%, khác biệt có ý nghĩa thống kê (p<0,05) so với mô hình IFAS đối chứng sau ba ngày khảo sát.
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