River Water Treatment Research Articles

Hydrophilic modification of poly(vinylidene fluoride) ultrafiltration membranes by surface UV photo-grafting with N,N′-methylene-bisacrylamide as monomer and Ce(IV) as initiator

A UV photo-grafting method was utilised to enhance the hydrophilicity and anti-fouling property of self-made poly(vinylidene fluoride) (PVDF) ultrafiltration membranes. N,N′-methylene-bisacrylamide (MBAA) was used as monomer and Ce(IV) was used as initiator to obtain balance between grafting treatment consumption and enhanced performance. MBAA could be grafted onto the surface of pure PVDF membranes through a water-phase grafting method under UV photoradiation. When the MBAA concentration was 0.07 mol/L, the Ce(IV) concentration was 0.04 mol/L, and the irradiation duration was 3 min, the membrane surface was grafted with a sufficient amount of monomer under a UV photoradiation intensity of 5.0 mW/cm2. The water contact angle on the surface of the modified membrane decreased by approximately 16°, and flux recovery increased by approximately 40% compared with the pure PVDF membrane when treating river water. For bovine serum albumin rejection and porosity measurements no significant changes were observed between pure PVDF and graft-treated membranes. The enhanced performance of the modified membrane in this work was moderate, but the UV irradiation duration (3 min) was short. The integrative effects of UV modification in this work were satisfactory when both irradiation duration and enhanced performance were considered.

Comparative study of preozonation and prechlorination efficiency in processes of the Dnieper water treatment

The efficiency of the Dnieper River water treatment was investigated in processes of preliminary oxidation, coagulation and adsorption using ozone and chlorine. It was shown that preozonation of water enhances the total effect of its treatment from dissolved organic matter by 54% as compared to prechlorination.

Sulfonamide and tetracycline resistance genes in total- and culturable-bacterial assemblages in South African aquatic environments.

Antibiotic resistant bacteria are ubiquitous in the natural environment. The introduction of effluent derived antibiotic resistance genes (ARGs) into aquatic environments is of concern in the spreading of genetic risk. This study showed the prevalence of sulfonamide and tetracycline resistance genes, sul1, sul2, sul3, and tet(M), in the total bacterial assemblage and colony forming bacterial assemblage in river and estuarine water and sewage treatment plants (STP) in South Africa. There was no correlation between antibiotic concentrations and ARGs, suggesting the targeted ARGs are spread in a wide area without connection to selection pressure. Among sul genes, sul1 and sul2 were major genes in the total (over 10-2 copies/16S) and colony forming bacteria assemblages (∼10-1 copies/16S). In urban waters, the sul3 gene was mostly not detectable in total and culturable assemblages, suggesting sul3 is not abundant. tet(M) was found in natural assemblages with 10-3 copies/16S level in STP, but was not detected in colony forming bacteria, suggesting the non-culturable (yet-to-be cultured) bacterial community in urban surface waters and STP effluent possess the tet(M) gene. Sulfamethoxazole (SMX) resistant (SMXr) and oxytetracycline (OTC) resistant (OTCr) bacterial communities in urban waters possessed not only sul1 and sul2 but also sul3 and tet(M) genes. These genes are widely distributed in SMXr and OTCr bacteria. In conclusion, urban river and estuarine water and STP effluent in the Durban area were highly contaminated with ARGs, and the yet-to-be cultured bacterial community may act as a non-visible ARG reservoir in certain situations.

Comparison of various types of biomedia in river water treatment using attached growth activated sludge process

ABSTRACTPurification and beautification projects of river water in Malaysia involve biological treatment to remove pollutants. Activated sludge processes application on river water treatment proved successful performance. Attached growth system with biomedia increases biomass concentration and rates of contaminant degradation. In this work, several attached growth biological reactors were operated in parallel to treat river water in laboratory-scale experiment. Seven biological reactors were filled with different types of plastic biomedia, one was filled with assorted gravel and one left blank as a control. Monitoring of reactors’ performance was carried out to evaluate their performance. Parameters were tested throughout the steady-state period after acclimatization. The results were used to compute the Malaysian water quality index. The targeted removal efficiency was to achieve Class II in the National Water Quality Standard for Malaysian River and Lake Water quality, which was not attained. The treated effluent from the reactors ranged between Class III and IV.

Control of the Ozonation by-Products by O<sub>3</sub>/BAC in Shanxi Yellow River Water Treatment

While ozonation and biological activated carbon (O3/BAC) process was widely used in advanced water treatment, the control of ozonation by-product was one of the most important objects in water treatment. In this study, the filtered water of Huyan water plant, treating Yellow River water in Shanxi, was used as the raw water to investigate the control of ozonation by-products and the biological stability by O3/BAC process. Results showed that the bromate, formaldehyde and AOC concentration of ozonation effluent were increased, yet BAC filter could effectively reduce the concentration of the by-products. When ozone dosage was less than 3.5 mg/L, the bromate of BAC filter effluent was lower than 10 ug/L. And the formaldehyde was less than 20 ug/L in the whole range of ozone dosage. Moreover, the optimal ozone dosage for the highest AOC removal of 63.25% was 2.0 mg/L. The results could provide an operation parameter for Shanxi Yellow River water advanced treatment, thus to ensure the water quality safety.

Treatment of Polluted Hindon River Water by Electrochemical Technique

River Hindon is one of the most polluted rivers in western Uttar Pradesh, India. Treatment of Hindon river water is a challenging task due to large variety of inorganic, organic chemicals and microorganisms. The objective of present work is to study the application of electrochemical technique in the treatment of polluted Hindon river water. Experiments were carried out in an electrochemical cell by sacrificial electrodes, iron as anode and aluminium as cathode in a batch process. Effect of operating variables, viz., current density and electrolysis period was studied for reduction of Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Dissolved Solid (TDS), Total Suspended Solid (TSS), Dissolved Oxygen (DO), Total Hardness (TH), Total Alkalinity (TA) and Microbial Population (MP) at room temperature (25 0 C). Other parameters like pH and power consumption were also investigated. The applied current density and electrolysis period were found to effect significantly in reducing all parameters. The benefits of this process were observed in reducing capital and operating costs compared to other conventional treatment processes.

An energy-efficient membrane bioreactor for on-site treatment and recovery of wastewater

The present study describes the development of a new type of aerated membrane bioreactor referred to as a biologically activated membrane bioreactor (BAMBi) for on-site treatment of high-strength wastewater. The treated wastewater is reused for flushing and personal hygiene. BAMBi is an adaptation of a gravity-driven membrane reactor, originally developed for the purpose of treating river water to drinking water quality. Initially, a series of reactor configurations were tested and it was found that the simplest possible configuration could treat the wastewater to an acceptable standard, provided that a polishing step for color removal and disinfection was introduced. A commercial electrolysis unit was utilized for polishing. The energy consumption of BAMBi is 0.8 kWh/m3 of water treated, which can be considered low for an on-site membrane bio reactor application.

Improvement of Coagulation Process for the Prut River Water Treatment using Aluminum Sulphate

The aim of presented research was to optimize the treatment process of the Prut River water. In order to realize the proposed goal, there were studied the following factors which can improve the process of coagulation: (i) the infl uence of stirring speed during coagulation and (ii) the infl uence of the concentration of the coagulant solution added in the process of coagulation. The optimal conditions of coagulation were established using the Jar-test method. Application of the recommended procedure contribute to the reduction of the coagulant dose, the contact time, the aluminum concentration in water and the expenses for water treatment.

Harnessing Buoyancy Force to Operate Mini Cost-Saving Water Treatment Plant for River Inlets

River pollution has been a global issue and the consequences of polluted rivers are significantly affecting human health and well-being. Meanwhile, water treatment plants (WTP) are often related to high energy cost. Nevertheless, there is an abundance of hydraulic energy stored in the flowing water, which can be converted into mechanical energy to operate the WTP. The focus of this paper is to describe an innovative method of harnessing buoyancy force to save the energy cost of commonly used motorized equipment in the conventional WTP. The benefit of this product is to create a green environment by utilizing a readily available hydraulic energy and restoring river water quality. This study has shown that a cost-saving water treatment plant operating based on buoyancy force is feasible. This product enables electricity cost to be minimized while treating river water at the same time.

Biomarkers of oxidative stress in rat for assessing toxicological effects of heavy metal pollution in river water.

Increasing use of heavy metals in various fields, their environmental persistency, and poor regulatory efforts have significantly increased their fraction in river water. We studied the effect of Musi river water pollution on oxidative stress biomarkers and histopathology in rat after 28days repeated oral treatment. River water analysis showed the presence of Zn and Pb at mg/l concentration and Ag, As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Sn, and Sb at μg/l concentration. River water treatment resulted in a dose-dependent accumulation of metals in rat organs, being more in liver followed by kidney and brain. Metal content in both control and low-dose group rat organs was below limit of detection. However, metal bioaccumulation in high- and medium-dose group organs as follows: liver-Zn (21.4 & 14.5μg/g), Cu (8.3 & 3.6μg/g), and Pb (8.2 & 0.4μg/g); kidney-Zn (16.2 & 7.9μg/g), Cu (3.5 & 1.4μg/g), Mn (2.9 & 0.5μg/g), and Pb (2.6 & 0.5μg/g); and brain-Zn (2.4 & 1.1μg/g), and Ni (1 & 0.3μg/g). These metals were present at high concentrations in respective organs than other metals. The increased heavy metal concentration in treated rat resulted significant increase in superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione S transferase enzymes activity, and lipid peroxidation in a dose-dependent manner. However, glutathione content and catalase activity were significantly decreased in treated rat organs. Histopathological examination also confirmed morphological changes in rat organs due to polluted river water treatment. In conclusion, the findings of this study clearly indicate the oxidative stress condition in rat organs due to repeated oral treatment of polluted Musi river water.

Functions of slags and gravels as substrates in large-scale demonstration constructed wetland systems for polluted river water treatment.

The choice of substrates with high adsorption capacity, yet readily available and economical is vital for sustainable pollutants removal in constructed wetlands (CWs). Two identical large-scale demonstration horizontal subsurface flow (HSSF) CWs (surface area, 340m(2); depth, 0.6m; HLR, 0.2m/day) with gravel or slag substrates were evaluated for their potential use in remediating polluted urban river water in the prevailing climate of northwest China. Batch experiments to elucidate phosphorus adsorption mechanisms indicated a higher adsorption capacity of slag (3.15g/kg) than gravel (0.81g/kg), whereby circa 20% more total phosphorus (TP) removal was recorded in HSSF-slag than HSSF-gravel. TP removal occurred predominantly via CaO-slag dissolution followed by Ca phosphate precipitation. Moreover, average removals of chemical oxygen demand and biochemical oxygen demand were approximately 10% higher in HSSF-slag than HSSF-gravel. Nevertheless, TP adsorption by slag seemed to get quickly saturated over the monitoring period, and the removal efficiency of the HSSF-slag approached that of the HSSF-gravel after 1-year continuous operation. In contrast, the two CWs achieved similar nitrogen removal during the 2-year monitoring period. Findings also indicated that gravel provided better support for the development of other wetland components such as biomass, whereby the biomass production and the amount of total nitrogen (TN;43.1-59.0g/m(2)) and TP (4.15-5.75g/m(2)) assimilated by local Phragmites australis in HSSF-gravel were higher than that in HSSF-slag (41.2-52.0g/m(2) and 3.96-4.07g/m(2), respectively). Overall, comparable pollutant removal rates could be achieved in large-scale HSSF CWs with either gravel or slag as substrate and provide a possible solution for polluted urban river remediation in northern China.

Effects of raw diatomite on coagulation performance and residual aluminum during the micropolluted raw water treatment with polyaluminum chloride

The effects of raw diatomite on coagulation performance (CP) and the contents of residual aluminum (RAl) during the Pearl River water treatment with polyaluminum chloride (PAC) were investigated. Results demonstrated that the addition of raw diatomite could significantly improve the CP. The removal efficiencies (REs) of turbidity, dissolved organic carbon and UV254 could achieve 97.63%, 44.31% and 52.31%, respectively, at PAC dose of 20 mg/L and diatomite dose of 40 mg/L. Furthermore, adding appropriate dose of diatomite (less than 40 mg/L) could greatly reduce the RAl contents. The residual total aluminum and residual total dissolved aluminum both reached the lowest concentrations (0.185 mg/L and 0.06 mg/L, respectively) when the PAC dose was 15 mg/L and diatomite dose was 40 mg/L.

Contribution of Sewage Treatment to Pollution Abatement of Urban Streams

In this study, we assessed the efficiency and effectiveness of the Vrishabhavathy Valley Treatment plant (VVTP) in Bengaluru city, which is the oldest STP in the city. Since VVTP treats both raw sewage and polluted river water, with the latter constituting 80% of the influent, we sampled water quality at locations upstream and downstream of the plant to evaluate overall efficacy as well. We found that VVTP is able to reduce biochemical oxygen demand (BOD 5 ) by only 47%. This low efficiency can be attributed to the high and variable levels of chemical oxygen demand, consistent with episodic industrial discharges. Moreover, the mean values of pH, dissolved oxygen, total suspended solids, BOD 5 , nitrates, faecal coliforms and faecal streptococcus did not change significantly between upstream and downstream locations. Treating river water using an STP is clearly not an efficacious way of improving river water quality. Thus, before setting up new STPs, sewerage boards need to invest in building the underground drainage network to bring raw sewage to existing STPs.

Characteristics of nitrogen and phosphorus removal by a surface-flow constructed wetland for polluted river water treatment.

The characteristics of nitrogen (N) and phosphorus (P) removal were studied during the 2-year operation of a free water surface flow wetland of 900 m² with hydraulic loading of 0.1 m/d to evaluate its potential to treat water from an urban stream polluted with municipal and industrial wastewater. Attention was focused on the removal of dissolved N and P by harvesting plants (local Phragmites australis and Typha orientalis) at the end of each growing season. According to findings, the removals of N and P increased from 47.1% and 17.6%, respectively, in the 1st year to 52.3% and 32.4%, respectively, in the 2nd year. Increments of N and P removal were largely attributable to plant biomass, which increased from an average dry weight of 1.77 kg/m² in the 1st year to 3.41 kg/m² in the 2nd year. The amount of nutrients assimilated by plants in the 2nd year was almost double that of the 1st year. Increasing biomass in the 2nd year also improved redox conditions in the substrate layer, which contributed to increasing the efficiency of N removal. Compared with T. orientalis, P. australis was more competitive and adapted to conditions in the wetland better; it regenerated more vigorously and contributed more to nutrient removal.

Effect of irrigation water sources and sowing dates on pesticide residues and chemical composition of sugar beet

Investigation on the influence of irrigation water sources and sowing dates on pesticide residues, chemical composition and productivity of sugar beet revealed sowing date in August increased SPAd value and sugar %. The sowing date in october produced the maximum values of length and diameter root growth, yield (ton/fed), sugar (ton/fed) and leaves (ton/fed) of sugar beet at harvest. Further sowing date and irrigation water sources affected pesticides dissipation in soil. The detected amounts of residues were high in october cultivation than August; also, pesticide residues more degradable in soil irrigated by drainage water. The detected pesticide residues in roots and leaves were below MrL, except chlorpyrifos in case of river and mix water treatments during october sowing date. Sugar beet leaves contained much higher concentration of heavy metals than roots; also, plants irrigated by drainage water contained high amounts of heavy metals than other treatments.

Performance of experimental horizontal subsurface-flow-constructed wetlands treating river water: effect of substrate, configuration, hydraulic retention time, temperature and external carbon source

The water quality of Yapu River flowing into Lake Taihu was monitored for one year and the effects of substrate, configuration, hydraulic retention time (HRT) and temperature on nitrogen removal were evaluated in five pilot-scale horizontal subsurface-flow-constructed wetlands (CWs). Additionally, the impact of adding external carbon on nitrogen removal was investigated. Yapu River was shown to be eutrophic, with a low C/N ratio (COD/TN ≤ 1.5) and the main pollutant was total nitrogen (TN ≥ 2 mg/L). CWs with substrates of combined gravel-zeolite and gravel-ceramsite showed higher ammonium nitrogen (NH4+-N) and chemical oxygen demand (COD) removal efficiencies than the CWs with gravel substrates. Trapezoidal CWs showed improved dissolved oxygen in the front when compared with the rectangular CWs, enabling complete nitrification. A longer HRT (four days) improved the removal efficiencies of organics, nitrogen, and phosphorus. CWs performed better during the warm period. Moreover, addition of 400 g cattail litter during winter led to increased influent of COD. The average removal efficiencies of NO3--N and TN were increasing up to 90.5 and 85.3%, respectively.

Laboratory and pilot plant studies on electrochemical pretreatment of drinking water

Human health risks associated with drinking water chlorination disinfection have been identified, and the development of new disinfecting methods to minimize the risks with less energy and chemicals is the direction of water treatment industry. In this study, an electrochemical system was investigated for drinking water treatment in an undivided electrochemical reactor using Ti/RuO2–IrO2 anode and graphite felt cathode. The reactor configuration was designed in such a way that the angle of the electrodes was adjustable between 0° and 90°. It was found that the laboratory reactor (660 × 620 mm size) with electrodes positioned between 30° and 65° provided satisfactory results at a treatment capacity of 250 L/h water. A pilot plant test was conducted for treatment of Yellow River water using four laboratory-scale reactors in parallel, and the electrochemical treatment was compared with chemical disinfection using sodium hypochlorite, ozone, and potassium permanganate in the pilot plant facility. The results demonstrate that the electrochemical treatment is superior to chemical disinfection using sodium hypochlorite, ozone, and potassium permanganate in terms of removal of taste and odor and formation of disinfection byproducts.

Production of a bioflocculant from Aspergillus niger using palm oil mill effluent as carbon source

This study evaluated the potential of bioflocculant production from Aspergillus niger using palm oil mill effluent (POME) as carbon source. The bioflocculant named PM-5 produced by A. niger showed a good flocculating capability and flocculating rate of 76.8% to kaolin suspension could be achieved at 60h of culture time. Glutamic acid was the most favorable nitrogen source for A. niger in bioflocculant production at pH 6 and temperature 35°C. The chemical composition of purified PM-5 was mainly carbohydrate and protein with 66.8% and 31.4%, respectively. Results showed the novel bioflocculant (PM-5) had high potential to treat river water from colloids and 63% of turbidity removal with the present of Ca2+ ion.

Simultaneous removal of ammonium and phosphate from eutrophic waters using natural calcium-rich attapulgite-based versatile adsorbent

In this study, natural calcium-rich attapulgite (NCAP) was used to develop a versatile adsorbent for simultaneous removal of ammonium and phosphate from contaminated waters. Batch studies indicated that a combination of mixed salts and thermal treatments imparted the modified NCAP (named NCAP-NM) with the maximum nitrogen and phosphorus sorption capacity. This versatile adsorbent displayed a very fast nutrient adsorption rate and can, after 1h of adsorption, lower a solution enriched with 20mg/L of nutrients to <0.01mg P/L and 0.354mgN/L with a dosage of 30g/L. Fixed column adsorption studies indicated that sorption of phosphate was predominately affected by HCO3−, while sorption of ammonium was predominately affected by Ca2+. The result of a real-world application indicated that NCAP-NM could purify 1440 and 1000 bed volumes of water for phosphate and ammonium, respectively, in eutrophic river water treatment. While SEM-EDS and XPS analysis confirmed a dual function in the nutrient removal process utilizing NCAP-NM where phosphate was removed through precipitation by calcium, and ammonium was exchanged with magnesium and sodium in the adsorbent. These results offer a promising new method for lake eutrophication control if NCAP-NM is used as the adsorbent for nitrogen and phosphorus removal.

Development of a whole community genome amplification-assisted DNA microarray method to detect functional genes involved in the nitrogen cycle.

A novel DNA microarray analysis targeting key functional genes involved in most nitrogen cycling reactions was developed to comprehensively analyze microbial populations associated with the nitrogen cycle. The developed microarray contained 876 oligonucleotide probes based on the nucleotide sequences of the nif, amo, hao/hzo, nap, nar, nirK, nirS, nrf, cnor, qnor and nos genes. An analytical method combining detection by the designed microarray with whole community genome amplification was then applied to monitor the nitrogen cycling microorganisms in river water and wastewater treatment sludge samples. The developed method revealed that nitrogen cycling microorganisms in river water appeared to become less diverse in response to input of effluent from municipal wastewater treatment plants. Additionally, the nitrogen cycling community associated with anaerobic ammonium oxidation and partial nitrification reactors could be reasonably analyzed by the developed method. However, the results obtained for two activated sludge samples from municipal wastewater treatment plants with almost equivalent wastewater treatment performance differed greatly from each other. These results suggested that the developed method is useful for comprehensive analysis of nitrogen cycling microorganisms, although its applicability to complex samples with abundant untargeted populations should be further examined.