微污染水源饮用水处理技术展望

现有的水源常规水处理工艺已难以满足饮用水水质要求,为了达到饮用水水质标准,需要强化常规水处理工艺,对原水进行预处理或深度处理。本文对微污染水源常规处理的各种工艺方法以及在各工艺中应相应增加的新工艺新技术进行综述,以期今后在面对有机污染物日益严重的水源水而又要生产出合格的饮用水时,对水处理工艺选择的基建投资、运行成本和维护管理等基本必要条件提供一些技术概念支持。

2010-2014年某市水处理剂聚氯化铝质量分析

目的了解某市生活饮用水水处理剂使用和生产的质量情况,为加强相关卫生安全监管提供依据。方法对2010-2014年某市集中式供水厂及水处理剂生产厂使用和生产的水处理剂聚氯化铝进行采样,依据《生活饮用水用聚氯化铝》(GB 15892-2009)进行检测和评价,并用对测定结果进行统计分析。结果共抽检432份样品,合格率为96.22%。水厂样品合格率96.10%,净水剂生产厂产品合格率为97.37%;5年间的合格率分别为93.97%、100.00%、84.31%、98.96%、100.00%;各检测指标合格率盐基度、p H、镉、六价铬均为100.00%,砷99.52%、汞99.29%、铅99.05%、水不溶物99.05%、氧化铝98.81%。结论某市5年的水处理剂质量较好,氧化铝不达标为主要的质量问题,个别样品重金属略有超标,结果提示某市生活饮用水水处理剂使用较卫生安全。

Ordinary Toxicity of Chlorine Dioxide and By-products Chlorite and Chlorate in Water

Acute toxicity and accumulated toxicity of chlorine dioxide (ClO2) and by-products chlorite (ClO2-) and chlorate (ClO3-) in water acted on mice are studied by the method of Horn and accumulation coefficient. Subchronic toxicity of the mixture of ClO2 and ClO2-and ClO3- in water acted on rat is studied though feeding test for 90 days, including statistical analysis of variance on weight gaining, food utilization efficiency,index of blood and serum,liver (or kidney) to body weight ratio, and histopathological examination on liver and kidney. The results show that aqueous solution of ClO2, NaClO2 and NaClO3 ( with the concentration of 276.5 mg/L, 200 mg/L and 200 mg/L respectively) and the mixed aqueous solution of ClO2 with the concentration of 553 mg/L are actually non-poisonous , and non-cumulative aqueous solution as well.

Observation and simulation of 2-methylisoborneol in the Qingcaosha Reservoir,Changjiang estuary

2-Methylisoborneol(2-MIB) is a cyanobacterial metabolite that is responsible for many taste and odor(T&O) complaints related to the aesthetics of drinking water and poses a problem for water authorities because it is recalcitrant during conventional water treatment. A numerical model was developed to simulate 2-MIB in the Qingcaosha Reservoir, an estuarine drinking water resource in the Changjiang estuary with known 2-MIB episodes. The objective of this study was to numerically simulate the generation and release processes of 2-MIB in the reservoir and to provide useful information for better management of drinking water resources experiencing T&O problems caused by cyanobacteria. The simulation results from 2009 to 2013 showed that the simulated 2-MIB concentrations corresponded well to the observational data. 2-MIB was released mainly during periods of low dissolved oxygen(DO) levels with an adequate potential sediment source. The temporal and spatial variations in nutrients, chlorophyll-a(Chl-a), Cyanophyta and 2-MIB were presented and analyzed during 2009 to 2013. According to the study results, high-concentration areas and peak levels of 2-MIB can be controlled by inhibiting algal growth and increasing oxygen levels in the water, which can be achieved via adequate water exchange and oxygen exposure in the reservoir, respectively.

Immobilization biological activated carbon used in advanced drinking water treatment

Bacteria separated from a mature filter bed of groundwater treatment plants were incubated in a culture media containing iron and manganese. A consortium of 5 strains of bacteria removing iron and manganese were obtained by repeated enrichment culturing. It was shown from the experiments of effect factors that ironmanganese removal bacteria in the euhure media containing both Fe and Mn grew better than in that containing only Fe, however, they were unable to grow in the culture media containing only Mn. When comparing the bacteria biomass in the case ofp （DO） ：2.8 mg/L andp （DO） ：9. 0 mg/L, no significant difference was found. The engineering bacteria removing the organic and the bacteria removing iron and manganese were simuhaneously inoculated into activated carbon reactor to treat the effluent of distribution network. The experimental results showed that by using IBAC （ Immobilization Biological Activated Carbon） treatment, the removal efficiency of iron, manganese and permanganate index was more than 98% , 96% and 55% , respectively. After the influent with turbidity of 1.5 NTU, color of 25 degree and oflbnsive odor was treated, the turbidity and color of effluence were less than 0.5 NTU and 15 degree, respectively, and it was odorless. It is determined that the cooperation function of engineering bacteria and activated carbon achieved advanced drinking water treatment.

Pilot scale treatment of low turbidity water using compound bioflocculant and polymerized aluminium ferrum chloride

To investigate the application of compound bioflocculant （CBF） in drinking water treatment at pilot plant, CBF and polymerized aluminium ferrum chloride （PAFC） coagulant were used to treat raw water taken from Longhupao Reservoir in Heilongjiang Province for the removal of turbidity, COl）, UV254 and residual Al. Coagulation test shows that the coagulation enhanced by CBF and PAFC exhibits more effective performance than that enhanced by the individual of them, and the total combination dosage is lower than that of the individual. The residual Al from PAFC can be removed efficiently by CBF. The removal efficiency of turbidity reaches 76.6% by combining CBF of 2 mg/L and PAFC of 15 mg/L, COl） is decreased from 3.80 mg/L to 1.62 mg/ L, and the concentration of residual Al is only 0. 033 mg/L in the product water. It can be speculated that adsorption-bridging and sweep-coagulation processes are predominant in the flocculation process by the combination of CBF and PAFC.

Pilot Study on Drinking Water Advanced Treatment by GAC-MF System

The pilot performance of the combined GAC-MF membrane process for drinking water advanced treatment was described. In the process of GAC adsorption, under the conditions of 20 min HRT and 6 m/h filtration rate, the removal efficiencies of UV_(254) and trichloromethane could reach 40% and 50% respectively and the UV_(254) and trichloromethane in system effluent was less than 0.015 cm^(-1) and 5μg/L respectively. In the post MF membrane process, MF membrane effectively retained the particles and bacteria in raw water. The effluent turbidity was less than 0.2 NTU and no bacteria were detected at all in permeate. A computer-controlled system was employed to control this system. The membrane operating parameters of backwash interval, duration and flux were studied. The backwash interval of 10-min, 20-min and 60-min was researched respectively, and the variation of trans-membrane pressure was also analyzed. Consequently short backwash interval was recommended under the same water consume.

Impacts of Coagulation Pretreatment on MF Filtration and a Comparative Study of Different Membrane Module Types

Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products （D/DBP） Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particles and disinfectant tolerant microorganisms as well as natural organic matter （NOM）. For drinking water production, the use of membrane filtration processes such as microfiltration and ultrafiltration （MF/UF） alone to satisfy the turbidity, particle and microorganism removal a requirement of the surface water treatment regulation （SWTR） is not enough. MF/UF treatment processes can achieve only nominal （10 percent） removal of disinfection by-products （DBP） precursors （James, et al., 1995）. On the other hand, too fast fouling can make the filtration processes more difficult to carry on. To solve these problems, many authors have been interested in installing coagulation pretreatment before membrane filtration to improve membrane performance. However, previous studies reported conflicting results. Some supported the effectiveness of coagulation pretreatment, while others contended that coagulation aggravated membrane performance. This research aims to identify the effects of coagulation pretreatment on membrane filtration through a pilot study using PVDF membrane in combination with analyzing the rationale of coagulation. Another objective of this research was to evaluate the different impacts on membrane performance of using different membrane modules （the submerged module and pressured module）. The results showed that coagulation pretreatment greatly improved the membrane performance, extending the filtration time as well as reducing the permeated organic level, and that the submerged module is much more efficient than the pressured module.

Problems of drinking water treatment along Ismailia Canal Province, Egypt

The present drinking water purification system in Egypt uses surface water as a raw water supply without a preliminary filtration process.On the other hand,chlorine gas is added as a disinfectant agent in two steps,pre-and post-chlorination.Due to these reasons most of water treatment plants suffer low filtering effectiveness and produce the trihalomethane(THM) species as a chlorination by-product.The Ismailia Canal represents the most distal downstream of the main Nile River.Thus its water contains all the proceeded pollutants discharged into the Nile.In addition,the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year.Moreover,the wide industrial zone along the upstream course of the canal enriches the canal water with high concentrations of heavy metals.The obtained results indicate that the canal gains up to 24.06×106 m3 of water from the surrounding shallow aquifer during the closing period of the High Dam gates,while during the rest of the year,the canal acts as an influent stream losing about 99.6×106 m3 of its water budget.The reduction of total organic carbon(TOC) and suspended particulate matters(SPMs) should be one of the central goals of any treatment plan to avoid the disinfectants by-products.The combination of sedimentation basins,gravel pre-filtration and slow sand filtration,and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC,SPM and heavy metals.Moreover,it reduces the use of disinfectants chemicals and lowers the treatment costs.However,this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application.

Operation Characteristics of Treating Surface Water with Polyvinylchloride Hollow Fiber Ultrafiltration Membrane

A pilot plant study on a polyvinylchloride hollow fiber ultrafiltration membrane process was conducted for treating surface water. The membrane system was operated in the dead-end filtration mode under different constant permeate fluxes. The results show that the optimized operation (transmembrane pressure≤0.1 MPa, filtration time≤30 min) with a hydraulic cleaning (30 s) and a chemical cleaning (30 min, the chemical cleaning was performed after 16 cycles of filtration ) ensures a quite steady flux (1 100 L/(m^2·h·MPa)) and good permeate quality (turbidity<0.1 NTU). A full-scale plant can be suggested to operate with a mixed strategy of constant permeate flux mode (transmembrane pressure≤0.1 MPa) and constant transmembrane pressure mode. When the temperature of raw water becomes below 5 ℃, a constant transmembrane pressure mode should be used; otherwise a constant permeate flux mode (transmembrane pressure≤0.1 MPa) can be operated. In this way, irreversible fouling of ultrafiltration membrane can be minimized to keep a stable flux and make the life of membrane longer.

Integrated Phytodisinfectant-Sand Filter Drum for Household Water Treatment in Subsaharan Africa

This report details an assessment of an integrated low-technology phytodisinfectant-sand filter drum for household water and waste water treatment for sub-Saharan Africa, using bacterial culture tests, total solids, and turbidity amongst others is presented. A hundred litres of very dirty/turbid water （130.3 NTU） was pretreated with 100 seeds of Moringa olieferaand further filtered through a sand filter drum （120 litres carrying capacity） made of fine, coarse sand, charcoal and gravel. The mean total aerobic mesophilic bacterial counts, E coli, coliform, pseudomonas, and yeast counts, as well as turbidity of untreated water drastically reduced to wealth health organization acceptable standards for potable water. The results indicated that the mean values of the same parameters for sand filtered pond water alone was significantly lower than the corresponding mean values obtained for Moringa treated pond water. The findings from this study suggest strongly that an integral of two natural water purification technologies （phytodisinfectant-sand filter drum） could be applied for the treatment of all types of contaminated water rendering it free from pathogens for potable and non potable uses.

Advanced purification of filtered water by aerobic IBAC

Conventional water purified processes have low removal efficiencies for low concentrations of ammonia nitrogen, nitrite nitrogen and micro-pollutants. The efficiency and mechanisms of a novel immobilized biological activated carbon (IBAC) process to remove those pollutants from treated potable water was investigated. Operated at a hydraulic retention time of 24 minutes, the IBAC process achieved ammonia nitrogen, nitrite nitrogen and organic micro-pollutants (measured as COD equivalent) removal efficiencies of 95%, 96% and 37%, respectively. A GC/MS analysis of the organic micro-pollutants revealed that the initial 24 organic compounds in the in-coming water were reduced to 7 after the IBAC treatment. The organic micro-pollutant removal efficiency decreased with decreasing in-coming concentrations. Pollutant reduction in the IBAC process was achieved by a rapid physical adsorption on the activated carbon, which effectively retained the pollutants in the system despite the short hydraulic retention time, followed by a slower biological enzymatic degradation of the pollutants.

Comparative Study of Ozonation and Catalyzed Ozonation Processes for Drinking Water Treatment by Pilot Test

The ozone consumption effect and organic removal ability of metal coated cordierite ceramic honeycombs catalytic ozonation （catazone） process and ozonation process were comparatively studied by pilot-scale experiments. By Scan Electron Microscope （SEM）, Atomic Force Microscope （AFM）, BET, and X-ray photoelectron spectroscopy （XPS） analysis, metal oxides attached to ceramic surface were found to be in the form of crystal cluster, and the pore structure of ceramics was less developed. The air flow statuses of vacant catazone and ozone contactors were inclined to be plug-flow and mixed flow, respectively. Comparing with ozonation process, the ozone mass transfer efficiency of catazone process is lower, and the ozone decomposition efficiency of catazone is higher. The former effect is more obvious in semi-batch experiment, and the latter effect is more obvious in continuous-flow experiment. Unsaturated organics removal efflciencies of the two oxidation processes are similar, and are less affected by dissolved ozone concentration when it is higher than 1 mg/L. More dissolved organics were detected in catazone process in continuous.flow reaction, and more CH3CI3 formation potential （CH3CI3FP） was removed by catazone in semi-batch mode, especially in the water with lower UV254 .

Optimization of ultrasonic parameters for effective detachment of biofilm cells in an actual drinking water distribution system

It is important to obtain a considerable quantity of DNA from oligotrophic environments such as a drinking water distribution system(DWDS)to study microbial communities by molecular biotechnology,and DNA yield is always one of the biggest problems when performing metagenomic sequencing on drinking water samples.To obtain as many microbes as possible,ultrasound has been widely used in cell detachment,but studies on the optimal ultrasonic parameters for biofilm in DWDS have rarely been seen.The effects of three ultrasonic parameters,including power,duration,and the number of ultrasound treatments(USTs)on the selected monoculture bacteria(Pelomonas sp.)biofilm were studied first.Then the optimal values of each ultrasonic parameter were initially determined.Based on these values,three levels of each ultrasonic parameter were selected,and then an orthogonal experiment was conducted to further study drinking water biofilm,and finally the optimal ultrasonic parameters for the effective separation of biofilm cells in DWDS were determined.The results showed that the optimal ultrasonic power,duration,and the number of USTs are 13 W,1 min,and 15,respectively.A 20-min interval is needed between two USTs.The present optimal UST,which does not lose DNA quality,can increase the amount of extractable DNA by at least 4.78 times compared to samples without UST.This study provides a pretreatment methodology for extracting more and reliable DNA from biofilm in DWDS,and can better solve the problem of DNA collection in oligotrophic environments.