活性炭结合超滤及纳滤工艺深度处理饮用水的中试研究

金门岛内水库的富营养化程度严重,藻类所产生的臭味物质、有机碳及消毒副产物的浓度非常高,影响岛内民众健康.研究利用活性炭结合超滤及纳滤工艺,将甲基异莰醇-2、土臭素处理嗅阈值以下,将不可挥发溶解性有机炭(NPDOC)从6.4 mg/L降至0.2 mg/L;三卤甲烷生成势(THMFP)和卤乙酸生成势(HAAFP)可分别从489μg/L和656μg/L去除至38μg/L及17.6 μg/L,去除率分别为92%及97%.中试结果表明,各检测项目均符合台湾地区饮用水标准.由32位金门县自来水厂员工测试3种水的适饮性,其中经活性炭结合超滤及纳滤组合工艺处理后的水样水质为多数测试人员所接受.     

藻源臭味物质Geosmin与2-MIB的生成途径及控制研究

饮用水中的臭味问题不但严重影响水的感官特性,而且某些致臭化合物还会直接危害人体健康。蓝藻是地表饮用水水源中典型致臭物质土腥素(Geosmin)和二甲基异莰醇(2-MIB)的主要来源。以Geosmin和2-MIB的研究历史为主线,综述了土腥素和2-甲基异莰醇的生物合成和代谢途径以及由此产生的基于分子生物学的检测方法及未来的发展方向,为含有土嗅味原水的处理技术的遴选提供了理论依据。     

臭味层次分析法在上海市饮用水中的应用

介绍了臭味层次分析法(FPA)培训内容及其在上海市饮用水臭味识别中的应用。结果表明,经过培训的FPA臭味识别小组能够对水样中不同种类的异臭味进行定性和定量的评价分析;臭味检测人员对上海市水体中含有的典型致臭土霉味物质甲基异莰醇-2和腥臭味物质二甲基三硫的嗅阈值可分别达到1.69ng/L和24.4ng/L,并对这两种物质的强度等级评价有较好的重现性。采用FPA评价上海市地区原水及不同供水区域自来水的臭味特征及加标后不同浓度条件下的臭味强度特征,结果表明,FPA优于现行使用的臭味评价方法,能够及时、快速地反映水质问题,是可靠的感官分析方法。     

沉淀与气浮工艺单元处理太湖原水效果比较

针对典型的太湖湖泊水源水,通过中试对比混凝沉淀和混凝气浮两种工艺对太湖原水的处理效果。试验表明,气浮工艺单元对低温低浊水的浊度、UV254的去除率分别比沉淀工艺平均高14.94个百分点、7.51个百分点,对高温高藻水则平均高出5.77个百分点、5.62个百分点。气浮工艺较沉淀工艺能更好地去除藻类和藻毒素。对于CODMn、DOC、土臭素(GSM)、二甲基异冰片(MIB)的去除效果,气浮工艺单元略高于斜管沉淀。气浮工艺单元对各粒径等级的颗粒物去除率基本在90%以上。     

南方某市水源臭味物质识别及分布研究

用臭味层次分析法(FPA)、全二维气相色谱飞行时间质谱(GC×GC-TOFMS)结合臭味活性值(OAV)表征,对以SZ、SY、TG水库为代表的南方某市主要水源的臭味类型和臭味物质进行筛查识别。确定主要臭味类型为土霉味,主要土霉味物质为二甲基异莰醇(2-MIB)和土臭素(GSM)。利用优化后的顶空固相微萃取气相色谱质谱(HS-SPME-GC/MS)检测方法对3个主要水源中的2-MIB和GSM进行为期1年的检测分析,结果表明,SY和TG两水库中的2-MIB平均含量分别为48.06ng/L和41.41ng/L,SZ水库未检出。SZ、SY、TG 3座水库中GSM平均含量分别为2.55ng/L、4.89ng/L、4.30ng/L,在2-MIB和GSM两种臭味物质中,2-MIB对水源水土霉味贡献更大,为主要土霉味物质。     

预臭氧对深度工艺去除臭味和有机物的影响

采用中试研究臭氧生物活性炭深度处理工艺去除太湖水的臭味,考察臭味浓度变化以及预臭氧投加量对深度工艺去除土臭素和二甲基异茨醇的效果和影响。试验结果表明,在试验的臭味浓度变化范围内以及有预臭氧的情况下,深度工艺可有效去除臭味,出水的臭味浓度满足国家水质标准。试验还发现,砂滤在去除臭味上起到重要的作用,并与生物活性炭存在互补关系。     

高速给水曝气生物滤池投加高锰酸钾与粉末活性炭的研究

针对采用高速给水曝气生物滤池(BAF)—常规处理工艺处理南方地区季节性微污染原水时,可能遇到污染高峰期或应急状况而联用高锰酸钾(KMnO4)与粉末活性炭(PAC),通过中试研究选择合适的投加组合方式,并优化投加量。结果表明:选择在BAF之前投加高锰酸钾、BAF之后常规处理工艺之前投加PAC的联用方式能高效地去除CODMn、藻类、色度、臭和味,降低滤后水浊度。当高锰酸钾投加量为0.8mg/L、粉末活性炭投加量为8mg/L时,工艺对CODMn、藻类、色度、臭和味及浊度的去除率达到最大,BAF对CODMn、藻类、色度、臭和味及浊度的去除率分别为42.0%、42.7%、17.0%、17.6%及22.9%,砂滤出水的总去除率达75.9%、95.8%、58.2%、94.3%及99.24%。     

包头市画匠营子总水源厂冬季水质异味分析研究

通过对包头画匠营子总水源厂冬季水质进行长期监测分析,认为造成水质异味的主要物质为水源水中含有痕量藻类次生代谢产物(Geosmin、MIB、IPMP、TCA).在对黄河水、水库水进行长期监测的基础上分析得出是由于藻类的大量繁殖造成该水厂出厂水有异臭味.研究结果表明冬季水库藻类的总数及各种属,以绿藻门、硅藻门、隐藻门三大门类为主,其中以绿藻门的小球藻、鼓藻,隐藻门中的卵形隐藻、啮齿隐藻,硅藻门的圆筛藻、星杆藻最为常见.异味明显时,水库藻类数量一直在107个/L以上.还用OLSA-GC法测定了藻类分泌物--痕量致味物质土臭素、地霉素、TCA和IPMP的含量,MIB含量在29～102 ng/L,超出嗅阈值3～10倍;TCA范围为13～59 ng/L,超过其嗅阈值2～9倍;地霉素20～65 ng/L,超过其嗅阈值2～6倍;IPMP9～38 ng/L,超过其嗅阈值4～19倍.研究结果为今后解决包头市冬季饮用水中异味问题提供了基础资料.     

水处理工艺过程中有机物分子量分布规律

针对太湖流域某湖泊水源有机物分子量分布的特性,考察饮用水处理各工艺单元对有机物的去除效应。结果表明:原水以小分子量有机物为主,小于1k Dalton的有机物占36.1%;常规工艺对大分子量有机物去除率高,尤其对分子量在10k Dalton以上的有机物去除率达32.7%以上,但对小分子量有机物去除率低,其中分子量小于1k Dalton的有机物反而增加了12.6%左右。超滤深度处理工艺中PES膜工艺对小分子量有机物,特别是分子量小于10kDalton的有机物去除率达76.4%,出水UV254值及SUVA值比砂滤出水分别下降了22.0%和11.2%;PVDF膜工艺对各分子量有机物均有较好的去除,但对大分子有机物去除效果优于小分子有机物,其出水UV254值及SUVA值比砂滤出水分别下降了28.8%和6.3%。     

沉淀-气浮组合工艺处理低浊高藻水试验研究

针对北方地区地表水夏天高藻冬天低温低浊的水质特点,采用沉淀-气浮组合工艺进行了低浊高藻水净水效果的中试研究。通过试验,首先确定了混凝剂PAFC投加量4.5mg/L、进水流量0.6m~3/h和回流比8%的试验条件。在此试验条件下,沉淀-气浮组合工艺的平均出水浊度为0.75NTU,去除率达95.2%;出水的颗粒数总量4 800个/mL,去除率达95.9%,且对不同粒径区间颗粒数去除效果基本一致;出水COD_(Mn)为3.95mg/L,去除率为41.3%,出水藻类数量270万~900万个/L,去除率达96%;臭味物质2-MIB和GSM的含量均小于6×10~(-6) mg/L,低于国标参考值。试验结果表明,沉淀-气浮组合工艺对浊度、颗粒数、藻类、臭味物质等去除率较高,对CODMn有一定的去除效果,低浊高藻水适合采用沉淀-气浮组合工艺进行处理。     

Treatment of taste and odor material by oxidation and adsorption.

Massive blooms of blue-green algae in reservoirs produce the musty-earthy taste and odor, which are caused by compounds such as 2-MIB and geosmin. 2-MIB and geosmin are rarely removed by conventional water treatment. Their presence in the drinking water, even at low levels (ng/L), can be detected and it creates consumer complaints. So those concentrations have to be controlled as low as possible in the drinking water. The removals by oxidation (O3, Cl2, ClO2) and adsorption (PAC, filter/adsorber) were studied at laboratory and pilot plant (50 m3/d) to select suitable 2-MIB and geosmin treatment processes. The following conclusions were derived from the study. Both of the threshold odor levels for 2-MIB and geosmin appeared to be 30 ng/L as a consequence of a lab test. For any given PAC dosage in a jar-test, removal efficiencies of 2-MIB and geosmin were increased in proportion to PAC dosage and were independent of their initial concentration in raw water for the tested PAC dosages. In comparison of geosmin with 2-MIB, the adsorption efficiency of geosmin by PAC was superior to that of 2-MIB. The required PAC dosages to control below the threshold odor level were 30 mg/L for geosmin and 50 mg/L for 2-MIB at 100 ng/L of initial concentration. Removal efficiencies of odor materials by Cl2, ClO2, and O3 were very weak under the limited dosage (1.5 mg/L), however increased ozone dosage (3.8 mg O3/L) showed high removal efficiency (84.8% for 2-MIB) at contact time 6.4 minutes. According to the initial concentrations of 2-MIB and geosmin, their removal efficiencies by filter/adsorber differed from 25.7% to 88.4%. For all those, however, remaining concentrations of target materials in finished waters were maintained below 30 ng/L. The longer run-time given for the filter/adsorber, the higher the effluent concentration generated. So it is necessary that the run-time of the filter/adsorber be decreased, when 2-MIB or geosmin occurs in raw water.     

Removal of geosmin and 2-methylisoborneol by biological filtration.

The quality of drinking water is sometimes diminished by the presence of certain compounds that can impart particular tastes or odours. One of the most common and problematic types of taste and odour is the earthy/musty odour produced by geosmin (trans-1, 10-dimethyl-trans-9-decalol) and MIB (2-methylisoborneol). Taste and odour treatment processes including powdered activated carbon, and oxidation using chlorine, chloramines, potassium permanganate, and sometimes even ozone are largely ineffective for reducing these compounds to below their odour threshold concentration levels. Ozonation followed by biological filtration, however, has the potential to provide effective treatment. Ozone provides partial removal of geosmin and MIB but also creates other compounds more amenable to biodegradation and potentially undesirable biological instability. Subsequent biofiltration can remove residual geosmin and MIB in addition to removing these other biodegradable compounds. Bench scale experiments were conducted using two parallel filter columns containing fresh and exhausted granular activated carbon (GAC) media and sand. Source water consisted of dechlorinated tap water to which geosmin and MIB were added, as well as, a cocktail of easily biodegradable organic matter (i.e. typical ozonation by-products) in order to simulate water that had been subjected to ozonation prior to filtration. Using fresh GAC, total removals of geosmin ranged from 76 to 100% and total MIB removals ranged from 47% to 100%. The exhausted GAC initially removed less geosmin and MIB but removals increased over time. Overall the results of these experiments are encouraging for the use of biofiltration following ozonation as a means of geosmin and MIB removal. These results provide important information with respect to the role biofilters play during their startup phase in the reduction of these particular compounds. In addition, the results demonstrate the potential biofilters have in responding to transient geosmin and MIB episodes.     

Comparison between ozone and ferrate in oxidising geosmin and 2-MIB in water.

Among the chemicals causing taste and odour (T&O) in drinking water, the most commonly identified and problematic ones are geosmin and 2-MIB (2-methylisoborneol). Since the reported odour thresholds of geosmin and 2-MIB are as low as 4 and 8.5 ng/L, respectively, they are not readily removed by conventional water treatment processes. In this study, ozone (O3) and ferrate (Fe(VI)) were applied to oxidise geosmin and 2-MIB. Their performances were compared in terms of removal efficiency of geosmin and 2-MIB. In the case of O3, removal efficiency of geosmin and 2-MIB ozonation at different initial O3 doses, H2O2/O3 ratios and water temperatures were evaluated. The oxidation rates of geosmin and 2-MIB by Fe(VI) were measured within pH 6-8. The effect of H2O2 addition was also evaluated. In summary, O3, especially with H2O2, could almost completely oxidise geosmin and 2-MIB, while Fe(VI) could not oxidise them more than 25% at any pH that was considered in this study. This was attributed to the structure of the organics and high reaction selectivity of Fe(VI). Further study should be conducted to find the reason of inhibition of oxidation by Fe(VI).     

Occurrence of the Odor Compounds, 2-Methylisoborneol and Geosmin in Eastern Lake Ontario and the Upper St. Lawrence River

Unpleasant tastes and odors in drinking water from the upper St. Lawrence River were investigated in the fall of 1996 and 1997 as the result of increasing taste and odor events in recent years. Taste and odor events resulted in widespread public reaction to the earthy/musty tasting water produced and a need for accurate information to assist water treatment efforts. The presence of geosmin, (trans, trans-1,10-dimethyl-9-decalol) and 2-methylisoborneol (MIB2, 1,2,7,7-tetramethyl-exobicyclo[2.2.1]heptan-2-ol), the most common causes worldwide of earthy and musty odors in water, were investigated in eastern Lake Ontario and the upper St. Lawrence River. Gas chromatography-mass spectrometry was used for quantitation and confirmation of the presence of these compounds in water samples. Both geosmin and MIB2 were detected in river water samples at concentrations ranging from 5 to 20 ng/L and 2 to 25 ng/L, respectively. The compounds were also detected in southern coastal lake water which serves as a source to the St. Lawrence River, but not in mid-lake samples. Similar levels of geosmin and MIB2 were detected in untreated Lake St. Lawrence water, in samples taken following pre-chlorination for zebra mussel control, and in samples taken following conventional treatment at a water filtration plant.     

Removal of cyanobacterial metabolites through wastewater treatment plant filters

Wastewaters have the potential to proliferate excessive numbers of cyanobacteria due to high nutrient levels. This could translate to the production of metabolites, such as the saxitoxins, geosmin and 2-methylisoborneol (MIB), which can impair the quality of wastewater destined for re-use. Biological sand filtration was assessed for its ability to remove these metabolites from a wastewater. Results indicated that the sand filter was incapable of effectively removing the saxitoxins and in some instances, the effluent of the sand filter displayed greater toxicity than the influent. Conversely, the sand filter was able to effectively remove geosmin and MIB, with removal attributed to biodegradation. Granular activated carbon was employed as an alternative filter medium to remove the saxitoxins. Results showed similar removals to previous drinking water studies, where efficient removals were initially observed, followed by a decrease in the removal; a consequence of the presence of competing organics which reduced adsorption of the saxitoxins.     

Efficient taste and odour removal by water treatment plants around the Han River water supply system.

Seven major water treatment plants in Seoul Metropolitan Area, which are under Korea Water Resources Corporation (KOWACO)'s management, take water from the Paldang Reservoir in the Han River System for drinking water supply. There are taste and odour (T&O) problems in the finished water because the conventional treatment processes do not efficiently remove the T&O compounds. This study evaluated T&O removal by ozonation, granular activated carbon (GAC) treatment, powder activated carbon (PAC) and an advanced oxidation process in a pilot-scale treatment plant and bench-scale laboratory experiments. During T&O episodes, PAC alone was not adequate, but as a pretreatment together with GAC it could be a useful option. The optimal range of ozone dose was 1 to 2 mg/L at a contact time of 10 min. However, with ozone alone it was difficult to meet the T&O target of 3 TON and 15 ng/L of MIB or geosmin. The GAC adsorption capacity for DOC in the three GAC systems (F/A, GAC and O3 + GAC) at an EBCT of 14 min is mostly exhausted after 9 months. However, substantial TON removal continued for more than 2 years (>90,000 bed volumes). GAC was found to be effective for T&O control and the main removal mechanisms were adsorption capacity and biodegradation.     

吴淞江微污染水源水处理工艺的比较研究

采用预臭氧生物活性炭滤池、生物接触预氧化、PAC吸附预处理三种工艺对吴淞江微污染水源水处理进行研究;常温下,臭氧投加量2 mg/L,预臭氧生物活性炭滤池对氨氮的去除率维持在70%以上,出水NH3-N约1 mg/L,CODMn平均去除率34.16%;生物接触预氧化对氨氮去除率可达80%以上,但CODMn平均去除率只有7.6%;PAC对色度及臭味有良好的去除效果,但对其他物质去除率较低.三种工艺相比,作为水厂改造或备用应急方案,预臭氧生物活性炭滤池为最佳选择.     

Enhanced nitrogen removal using C/N load adjustment and real-time control strategy in sequencing batch reactors for swine wastewater treatment.

The laboratory-scale sequencing batch reactor (SBR) was used to study the effectiveness of an integrated strategy of real time control with C/N ratio adjustment for practical swine wastewater treatment. Swine waste was used as the external carbon source for continuous treatment in the SBR reactors. Oxidation-reduction potential and pH were used as parameters to control the continuous denitrification and nitrification process, respectively. A constant effluent quality could be obtained, despite drastic variations in the characteristics of influent wastewater. Also, a relatively complete removal of nutrients was always ensured, since the optimum quantity of the external carbon source could be provided for complete denitrification, and a flexible hydraulic retention time was achieved by the successful real-time control strategy. The average removal efficiencies of total organic carbon and nitrogen were over 94% and 95%, respectively.     

Combined membrane bioreactor (MBR) and reverse osmosis (RO) system for thin-film transistor-liquid crystal display TFT-LCD, industrial wastewater recycling.

In TFT-LCD industry, water plays a variety of roles as a cleaning agent and reaction solvent. As good quality water is increasingly a scarce resource and wastewater treatment costs rises, the once-through use of industrial water is becoming uneconomical and environmentally unacceptable. Instead, recycling of TFT-LCD industrial wastewater is become more attractive from both an economic and environmental perspective. This research is mainly to explore the capacity of TFT-LCD industrial wastewater recycling by the process combined with membrane bioreactor and reverse osmosis processes. Over the whole experimental period, the MBR process achieved a satisfactory organic removal. The COD could be removed with an average of over 97.3%. For TOC and BOD5 items, the average removal efficiencies were 97.8 and 99.4% respectively. The stable effluent quality and satisfactory removal performance were ensured by the efficient interception performance of the UF membrane device incorporated with biological reactor. Moreover, the MBR effluent did not contain any suspended solids and the SDI value was under 3. After treatment of RO, excellent water quality of permeate were under 5 mg/l, 2.5 mg/l and 150 micros/cm for COD, TOC and conductivity respectively. The treated water can be recycled for the cooling tower make-up water or other purposes.     

SPME-GC/MS/MS法测定水中2-甲基异莰醇和土臭素

研究了固相微萃取-气相色谱/二级质谱联用法测定水中2-甲基异坎醇(2-MIB)和土臭素(GSM)的方法.确定了最佳固相微萃取条件,NaCl加入量3 g,萃取温度60 ℃,搅拌时间30 min,搅拌速度800 r/min.在优化的仪器条件对臭味物质的测定结果显示,此方法灵敏度高,具有良好的精密度和准确度.2-MIB和GSM的相关系数均大于0.999;检出限及RSD分别为0.2 ng/L、0.4 ng/L和5.86%、6.50%;加标回收率分别为100.6%和92.3%.该方法操作简单省时,可满足水中痕量异臭物质的测定.