Performance Evaluation of Two Series Vertical Flow Filters for Wastewater Treatment: A Case Study of the Prototype Installed at Gaston Berger University, Saint-Louis, Senegal

This paper evaluates the efficacy of two sequential vertical flow filters (VFF), FV1 and FV2, implanted with Typha, in a pilot-scale wastewater treatment system. FV1 comprises three cells (FV1a, FV1b, and FV1c), while FV2 consists of two cells (FV2a and FV2b), each designed to reduce various physicochemical and microbiological pollutants from wastewater. Quantitative analyses show significant reductions in electrical conductivity (from 1331 to 1061 μS/cm), biochemical oxygen demand (BOD5 from 655.6 to 2.3 mg/L), chemical oxygen demand (COD from 1240 to 82.2 mg/L), total nitrogen (from 188 to 37.3 mg/L), and phosphates (from 70.9 to 14.6 mg/L). Notably, FV2 outperforms FV1, particularly in decreasing dissolved salts and BOD5 to remarkably low levels. Microbiological assessments reveal a substantial reduction in fecal coliforms, from an initial concentration of 7.5 log CFU/100mL to 3.7 log CFU/100mL, and a complete elimination of helminth eggs, achieving a 100% reduction rate in FV2. The study highlights the impact of design parameters, such as filter material, media depth, and plant species selection, on treatment outcomes. The findings suggest that the judicious choice of these components is critical for optimizing pollutant removal. For instance, different filtration materials show varying efficacies, with silex plus river gravel in FV1c achieving superior pollutant reduction rates. In conclusion, VFFs emerge as a promising solution for wastewater treatment, underscoring the importance of design optimization to enhance system efficiency. Continuous monitoring and adaptation of treatment practices are imperative to ensure water quality, allowing for safe environmental discharge or water reuse. The research advocates for ongoing improvements in wastewater treatment technologies, considering the environmental challenges of the current era. The study concludes with a call for further research to maximize the effectiveness of VFFs in water management.

Ammonium removal by modified zeolite from municipal wastewater

Ammonium removal by modified zeolite, H-form and Na-form zeolite, were examined by batch-type methods. The adsorption of ammonium on modified zeolite was exothermic process. The saturation adsorption capacity of ammonium on H-form and Na-form zeolite were 21.23 and 41.15 mg/g, respectively. After ten times adsorption-desorption-readsorption cycles the standard deviations of H-form and Na-form zeolite were 6.34% and 6.59%. The zeolite adsorption process has proved cost effective and practical in reducing ammonium by H-form and Na-form zeolite in municipal wastewater from concentration 27.68 mg/L to 2.80 mg/L and 5.91 mg/L.

Toxicity Reduction of Municipal Wastewater by Anaerobic-anoxic-oxic Process

Objective This study was conducted to optimize the operational parameters of anaerobic-anoxic-oxic （A^2/O） processes to reduce the toxicity of municipal wastewater and evaluate its ability to reduce toxicity. Methods A luminescent bacterium toxicity bioassay was employed to assess the toxicity of influent and effluent of each reactor in the A2/O system. Results The optimum operational parameters for toxicity reduction were as follows： anaerobic hydraulic retention time （HRT） = 2.8 h, anoxic HRT = 2.8 h, aerobic HRT = 6.9 h, sludge retention time （SRT） = 15 days and internal recycle ratio （IRR） = 100%. An important toxicity reduction （%） was observed in the optimized A2/O process, even when the toluene concentration of the influent was 120.7 mg·L^-1. Conclusions The toxicity of municipal wastewater was reduced significantly during the A^2/O process. A^2/O process can be used for toxicity reduction of municipal wastewater under toxic-shock loading.

Optimum municipal wastewater treatment plant design with consideration of uncertainty

A newly developed model for the optimum municipal wastewater treatment plant(MWTP) design is presented. Through introducing the interval variables, the model attempts to consider the effects of uncertainties caused by the fluctuation of the wastewater quality and quantity during the design of MWTP. The model solution procedure is illustrated in detail, and a numerical example is given to verify the feasibility and advantage of the model. Furthermore, the possibility of the model application is briefly outlined.

Performance evaluation of hybrid constructed wetlands for the treatment of municipal wastewater in developing countries

In developing countries,high cost of conventional wastewater treatment is a major hindrance in its application.Constructed wetlands(CWs)offer low-cost and effective solution to this issue.The current study aimed to evaluate an innovative maneuver of CWs i.e.hybrid flow constructed wetlands(HCWs)for municipal wastewater(MWW).The HCWs included two lab scale CWs;one horizontal and one vertical,in series.Local plant species were used.HCWs were operated in both,batch and continuous mode.Batch mode was used to(1)optimize detention time and(2)find pollutants removal efficiency.Continuous operation(at batch optimized retention time)was carried out for the evaluation of mass removal rate,r(g·m-2·d-1),volumetric rate constant,Kv(per day)and areal rate constant,Ka(m·d-1).Among two local plants tested,Pistia stratiotes gave better removal efficiency than Typha.Optimum detention time in HCWs was found to be 8 days(4+4 each).The optimum COD,BOD,TSS,TKN and P removal observed for Pistia stratiotes planted HCWs was 80%,84%,82%,71%and88%respectively.Effluent standards for COD,BOD and TSS were met at optimum conditions.The values of Kaand Kv demonstrated that more removal occurred in vertical flow as compared to horizontal flow CW.

Countermeasures of Reclaimed Municipal Wastewater for Safety of Agricultural Use in China

China is facing a severe water resource crisis, and the shortage of water for agricultural consumption is a prominent problem. Irrigation with reclaimed municipal wastewater that can reach the agricultural recycling standards is an important way to deal with water shortage in agricultural production. Owing to the complex sources of municipal wastewater, there are multifarious pollutants in municipal wastewater. Improper use of wastewater can cause potential risks to agoenvironment, agricultural products safety, and human health. This article deals with the current situation and the development prospects of reclaimed wastewater for agricultural use in China and abroad; the potential risks to human health and environmental pollution from the reclaimed municipal wastewater for agricultural reuse are also discussed. And some countermeasures and advices of reclaimed municipal wastewater for safety of agricultural reuse are provided.

Biodiversity of Duckweeds in Eastern China and Their Potential for Bioremediation of Municipal and Industrial Wastewater

Duckweed is a group of aquatic plants with the potential of wastewater remediation and fast accumulation of biomass. The accumulated biomass, rich in cellulose, starch and protein, can be used for biofuel, bio-fertilizer, animal feed and human food. Characterization of natural biodiversity of duckweed species is essential for the germplasm preservation and various practical applications. We have collected samples of duckweed in eastern China and characterized species biodiversity by genotyping, using chloroplast (atpF-atpH and psbK-psbI spacers). Spirodela polyrhiza was revealed as a clear dominant duckweed species in all locations of the area. Other duckweed species were identified as Landoltia punctata, Lemna aequinoctialis and Lemna turionifera. Selected isolates of these four species were used in the experiments to estimate their potential in removing nitrogen and phosphorus nutrients from municipal and industrial wastewater sampled at the local sewage plants. Duckweed was able to reduce the concentration of nitrogen up to 98% and phosphorus up to 96%. The presented data demonstrates high efficiency of the local duckweed isolates for bioremediation of different types of wastewater and the great potential of duckweed for wastewater treatment when incorporated into the purification chain.

Nitrogen removal from municipal wastewater by limit-oxic/anoxic/oxic biological aerated filter system

In this study,a three-stage biological aerated filter(BAF) system was proposed for the enhancement of nitrogen removal in the treatment of low carbon-to-nitrogen ratio(C/N ratio) municipal wastewater.Operational parameters were studied for each process for maximum nitrite accumulation in the nitrification step and nitrite adaptation in the denitrification step.Nitrite accumulation during nitrification could be controlled by the dissolved oxygen(DO) concentration,presenting a mean value of 40% at around 1.0 mg DO/L.Denitrification could be adapted to nitrite and the process was stable if nitrite in the reactor was keep low.Once the operational parameters were established,the process was stable and a steady state was maintained for over 30 days,and the various indexes of discharged water were up to the Discharge standard of pollutants for municipal wastewater treatment plant(GB18918-2002) Level-one A.It was concluded that the three-stage BAF system proposed in this study was excellent in nitrogen removal performance by employing three-column functioning as short-cut nitrification,short-cut denitrification and secondary nitrification,respectively.

Optimization and application of fluorescent in situ hybridization (FISH) process in EBPR fed with municipal wastewater

For sludge samples from EBPR reactor fed with municipal wastewater,fluorescent in situ hybridization (FISH) operation process including moisture chamber,pretreatment,treatment with lysozyme and Proteinase K and washing time was optimized and improved.Preserving box was chosen to be moisture chamber due to its bigger depth /radii ratio,good sealability and big volume contrast with Petri dish.3-5 mm diameter glass balls could disperse samples without destroying microorganism cells and community structure.Impurities and ECPs could be removed easily and sludge samples became thinner after dispersing which benefit the observation.Permeabilized cells with lysozyme and Proteinase K could enhance probe penetration before hybridization.Experiments of different treatment time with lysozyme and Proteinase K were carried out.Best results were observed when sludge samples treated with lysozyme 10 min/Proteinase K 20 min or lysozyme 20 min/Proteinase K 10 min.Slides were washed at 48 ℃ for 10,20,30,40 and 60 min in parallel.The best washing time was 20 min when washing temperature was 48 ℃.Fluorescent dye could residue when washing time was 10 min and washing out happened when washed for 30 min or more.

Technical Innovation of Land Treatment Systems for Municipal Wastewater in Northeast China

On the basis of ecological principles including holistic optimization, cycling and regeneration, and regional differentiation, land treatment systems (LTSs) for municipal wastewater were continuously explored and updated in the western Shenyang area and the Huolinhe area, China. Intensified pretreatment, addition of a man-made soil filtration layer, and use of an ecologically diversified secondary plant cover were proved to be technically feasible. Hydraulic loading was determined according to the assimilation capacity of soil ecosystems, thus ensuring safe operation of wastewater treatment. This modernized and alternative approach to wastewater treatment had been widely applied in middle-sized and small cities and towns of Northeast China, and these innovative systems in some areas had indicated favorable ecological, social, and economic benefits.

Mechanism of high concentration phosphorus wastewater treated by municipal solid waste incineration fly ash

The mechanism of removing phosphate by MSWI(municipal solid waste incineration)fly ash was investigated by SEM(scanning electron microscopy)with EDS(energy dispersion spectrum),XRD(X-ray diffraction),FT-IR(Fourier transform infrared spectroscopy),BET(specific surface area),and BJH(pore size distribution).The results indicate that the removal rate of phosphate(100 mg/L)in 50 mL phosphorus wastewater reaches at 99.9% as the dosage of MSWI fly ash being 0.9000 g under room temperature.The specific surface area of MSWI fly ash is less than 6.1 m2/g and the total pore volume is below 0.021 cm3/g,suggesting that the absorption capacity of calcite is too weak to play an important role in phosphate removal.SEM images show that drastic changes had taken place on its specific surface shape after reaction,and EDS tests indicate that some phosphate precipitates are formed and attached onto MSWI fly ash particles.Chemical precipitation is the main manner of phosphate removal and the main reaction is: 3Ca2++2 PO4 3-+xH2O→Ca3(PO4)2↓·xH2O.Besides,XRD tests show that the composition of MSWI fly ash is complex,but CaSO4 is likely to be the main source of Ca2+.The soluble heavy metals in MSWI fly ash are stabilized by phosphate.

Reed-wetland beds for municipal wastewater treatment

The performance of 11 reed-wetland beds for municipal wastewater treatment is described in this paper. The interrelation between pollutants removal (BOD5, SS, N and P) and hydraulic loading rate, organic loading rate, hydraulic retention time as well as the seasonal variation could be found in this study. The treatment efficiencies of reed beds are better than the secondary treatment standards with high and steady nitrogen and phosphorus removal. The total nitrogen and phosphorus of the final effluent are less than 10 mg/L and 0.5 mg/L, respectively.

Approaches to municipal wastewater irrigation and environmental protection

To reuse the water and nutrient resources from ecological point of view the goals, criteria and constraint conditions of the scientifically municipal wastewater irrigation are discussed as well as the practice in major municipal wastewater irrigation areas in China is introduced, of which particularly the effects of municipal water irrigation mixing with oil refinery wastewater on the agricultural ecosystem are studied and described. It has been revealed that benzo(a)pyrene in various parts of paddy crop is attributed to air pollution, water-soil pollution and biosynthesis of plant. Of exogenous contributions of benzo(a)pyrene in paddy shoot system under natural condition, the dominant factor is the air pollution, whereas the water-soil factor is considered to be secondary. Therefore, it is mostly urgent to control the air pollution source of benzo(a)pyrene, to which the edible parts of various green plants are exposed directly.

Photocatalytic Degradation of Organics in Municipal Treated Wastewater in a Re-Circulation Reactor

In this paper, an experimental investigation on the effect of parameters namely concentration, solar radiation intensity and exposure time on the photo oxidation of pollutants in secondary treated municipal wastewater has been presented. TiO2 was used as the photo catalyst and the experiments were carried out in the month of February 2012 in Oman. The reactor was a glass tube constructed with the provision of adding a reflector. The results showed that photo catalytic treatment is very effective for dilute solutions and the presence of reflector enhances the photo degradation. The reduction in Chemical Oxygen Demand (COD) obtained at the experimental conditions of 0.007 m3/hr flow rate, 15°?inclination angle and 1 g·L-1?TiO2 dosage was 18%. The presence of the reflector increased the degradation to 25% at the above experimental conditions.

Investigation of Biobutanol Efficiency of Chlorella sp. Cultivated in Municipal Wastewater

Many strains of microalgae can grow in wastewaters through their ability to utilize inorganic nitrogen and phosphorus in wastewater. The content of municipal wastewater changes from a location to others. Biofuel production from municipal wastewater has gained huge importance due to progresses in cultivation of microalgae in wastewaters. Biobutanol is produced by the acetone-butanol-ethanol (ABE) fermentation. In this study, we examined the biobutanol production efficiency of Chlorella sp. DEE006 which is cultivated in the municipal wastewater in flat-photobioreactor. Growth of microalgae was monitored at 680 nm using spectrophotometer and the biomass was also pre-treated with acidic hydrolysis (1 M H2SO4). Total carbohydrate and protein contents were measured. Fermented microalgae samples were taken for calculation of biobutanol concentration. We obtained both high biobutanol content (6.23 ± 0.19 g·L−1) and high bioethanol yield 0.16 ± 0.005 g (g sugar)−1. 50% wastewater had the highest biomass concentration (1930 ± 11 mg/L) among the wastewaters with five various concentrations. It had the highest biomass productivity with 0.28 ± 0.001 g L−1d−1. Also, it obtained the highest carbohydrate and protein concentration with 0.80 ± 0.02 gL−1 and 0.95 ± 0.01 gL−1, respectively. According to our results, Chlorella sp. DEE006 can be used for large scale biobutanol production in the future.

Optimize Operation of Partial Denitrification System for Simultaneous Treatment of Low C/N Municipal and Nitrate Wastewaters

In order to realize the simultaneous treatment of low C/N municipal and nitrate( NO3^--N) wastewaters,a sequencing batch reactor( SBR) was used to optimize the partial denitrification( PD),which the influent substrate and the anoxic reaction time were appropriately controlled. The carbon and nitrogen removal and the characteristic parameters of PD during long-term operation were studied. Experimental results showed that the PD showed stable characteristics of nitrogen and carbon removal and NO2^--N accumulation after an adaptation of 20 d with municipal wastewater used. The anoxic reaction time was extended from 50 to 70 min with the initial COD/NO3^--N decreased from 3. 0 to about 2. 5. When the influent NO3^--N was 117. 93 mg/L,the effluent NO2^--N and NAR were 23. 10 mg/L and 82. 26%,respectively,and the nitrogen and carbon removal rate reached 91. 76% and 65. 70%,respectively. The effluent NO2^--N/NH4^+ -N meantime reached 1.17-1. 22. Moreover,the cumulative concentration of NO2^--N and the system NAR increased linearly with the consumption of NO3^--N and COD,and the change trend was highly significant within 0-20 min,and gradually flattened.

Susceptibility of Some Selected Nitte Municipal Wastewater Sources to Trace Metals Pollution

The negative impacts of pollution due to trace metals in wastewater on aquatic ecosystem and related organisms in water bodies are on the increase. This paper deals with the investigation on the pollution indices of trace metals in selected wastewater samples of Nitte Town, Udupi District, Karnataka State, India. Twelve wastewater samples were obtained from Students Hostels, Auto-Service Workshop Station, Foundry, Laundry, Landfill Leachate and Wastewater Treatment Plant Inlet. The measured heavy metals in the samples include: Copper (Cu), Lead (Pb), Magnesium (Mg), Chromium (Cr), Nickel (Ni), Zinc (Zn), Manganese (Mn) and Cadmium (Cd), using the air-acetylene-operated Flame Atomic Absorption Spectrometer (FAAS), Avanta GM model. The results were all compared with the EPA Effluent Standards. Findings revealed that all samples recorded dwindling levels of trace metals pollution when compared with the Standards. The heaviest concentration occurred in Cd with as high as 1856.4 ppm as found in the Stale Landfill Leachate sample, while the least contaminating metal in the samples is Manganese which was detected in only Aerated Wastewater Treatment Plant sample (2.3 ppm). This study is therefore recommending Electro-coagulation treatment method for trace metals with high concentration levels like Cd, Pb, Mg and Cu, while those with lesser concentration such as Mn, Cr, Ni and Zn in the samples are suggested to be treated with chemical precipitation method.

Full Scale SBR Municipal Wastewater Treatment Facility Utilization of Simultaneous Nitrification/Denitrification Coupled with Traditional Nitrogen Removal to Meet Water Criterion

Simultaneous nitrification denitrification (SND) is a well-established phenomenon in biological nutrient removal activated sludge systems. Study at a municipal wastewater treatment facility sought to determine nitrogen removal effectiveness within a full-scale sequential batch reactor (SBR) system utilizing SND in conjunction with traditional nitrogen removal. In addition to characterizing extent of SND, the research examined the ability of SND to meet state-based effluent water quality standards. At the selected facility, the average SND efficiency during a two-month sampling period was 52.8%, paralleling results from similar SBR municipal wastewater systems. The observed SBR system had removal efficiencies > 99% for the influent to effluent -N concentrations. The SND process also resulted in average NO3-NO2-N concentration that was 82% lower than the theoretical concentration under comparable circumstances. Overall, nitrogen removal for this SBR system was >99% which typified results in other SND systems, but at a higher Total Nitrogen removal rate.