组合工艺控制有机物及消毒副产物前体物的特性研究

通过XAD-8树脂将水中有机物分成疏水性、亲水性两部分,对传统常规处理工艺(混凝气浮、过滤)和深度处理工艺(臭氧氧化、生物活性炭)出水的DOC,UV254THMFP,HAAFP指标以及疏水、亲水有机物去除率进行了检测分析。结果表明,生物活性炭(BAC)单元工艺能同时去除疏水性和亲水性两种有机物,且两者去除率均为最高。其次去除效果较好的是传统的常规工艺。臭氧工艺具有将天然的疏水性有机物氧化成可生化降解的亲水性小分子有机物的特点,在预臭氧+常规以及O3-BAC组合工艺中,起到了强化去除有机物和消毒副产物前体物的效果。     

Development of a hybrid ozonation biofilm-membrane filatration process for the production of drinking water.

Drinking water sources in Norway are characterized by high concentrations of natural organic matter (NOM), low alkalinity and low turbidity. The removal of NOM is therefore a general requirement in producing potable water. Drinking water treatment plants are commonly designed with coagulation direct filtration or NF spiral wound membrane processes. This study has investigated the feasibility and potential of a hybrid process combining ozonation and biofiltration with a rotating disk membrane for treating drinking water with high NOM concentrations. Ozonation will oxidize the NOM content removing colour and form biodegradable organic compounds, which can be removed in biological filters. A constructed water was used in this study which is representative of ozonated NOM-containing water. A rotating membrane disk bioreactor downstream the ozonation process was used to carry out both the biodegradation as well as biomass separation in the same reactor. Maintenance of biodegradation of the organic matter while controlling biofouling of the membrane and acceptable water production rates was the focus in the study. Three operating modes were investigated. Removal of the biodegradable organics was consistent throughout the study indicating that sufficient biomass was maintained in the reactor for all operating conditions tested. Biofouling control was not achieved through shear-induced cleaning by periodically rotating the membrane disks at high speed. By adding a small amount of sponges in the membrane chamber the biofouling could be controlled by mechanical cleaning of the membrane surface during disk rotation. The overall results indicate that the system can favorably be used in an ozonation/biofiltration process by carrying out both biodegradation as well as biomass separation in the same reactor.     

Importance of the order in enhancing EfOM removal by combination of BAC and MIEX(?)

Biological activated carbon (BAC) is operationally a simple treatment which can be employed to remove effluent organic matter (EfOM) from secondary wastewater effluent (SWWE). Unfortunately, BAC removes only a limited amount of dissolved organic carbon (DOC). Thus, maximizing DOC removal from SWWE using BAC is a major concern in wastewater reuse. This study has investigated a hybrid system of BAC and Magnetic Ion Exchange Resin (MIEX(?)) for the enhanced removal of DOC. Performance of both BAC prior to MIEX(?) (BAC/MIEX(?)) and reverse (MIEX(?)/BAC) combination was evaluated in terms of DOC removal. The BAC/MIEX(?) showed much better DOC removal. This is because microbial activity in the BAC bed converted MIEX(?) non-amenable DOC to MIEX(?) amenable DOC. As a result, BAC/MIEX(?) combination synergised DOC removal. In addition, BAC was also found to be highly effective in reducing MIEX(?) dose for a given DOC removal from SWWE.     

Dissolved and particulate organic carbon concentrations in stream water and relationships with land use in multiple-use watersheds of the Han River (Korea)

This study examines temporal variation in dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations in streams in the Han River watershed, Korea. On days without significant antecedent rain, DOC and POC concentrations ranged from 0.87 to 3.23 mg C/L and 0.24 to 2.92 mg C/L, respectively. Following rain events, both DOC and POC concentrations were higher. Soil and compost had δ¹³C values similar to stream δ¹³C-DOC and δ¹³C-POC. These results demonstrate the importance of studies using tracer approaches and the value of research on sources of organic carbon transported in streams in multiple use monsoonal watersheds.     

The effect of hydrostatic pressure on the decomposition of inundated terrestrial plant detritus of different quality in simulated reservoir formation

The formation of reservoirs usually incorporates the inundation of terrestrial vegetation in the basin. The decomposition of organic matter from the flooded vegetation may have several implications for reservoir functioning, including eutrophication and dissolved oxygen depletion. The hydrostatic pressure increases with depth in a reservoir, and its influence on the decomposition process has not previously been evaluated. This study was undertaken to evaluate the decomposition of terrestrial plant detritus of different qualities (leaves and branches) under different hydrostatic pressure conditions. Detritus were placed separately in glass bottles in the laboratory and incubated in tight stainless steel pressure vessels, simulating three different depths (surface, 30 and 100 m). The masses (mg) of particulate organic carbon (POC), dissolved organic carbon (DOC) and inorganic carbon (IC) were determined for the 4 months of the detritus decomposition simulated in this study. The mass values were transformed in percentages of the initial detritus carbon. The results of temporal variations of the compounds studied were fitted to a first‐order biphasic decay model. The hydrostatic pressure exhibited no significant effects on litter decomposition. On the other hand, the detritus chemical composition (i.e. the presence of labile and refractory compounds) was the determining factor for the decomposition curve shape and for the differences observed between the leaves and branches. The greatest POC loss from leaves, and resulting larger DOC mass, indicated the leaves were more labile than the branches. The results also indicated the branches are the main detritus remaining in a reservoir over time.     

黄土塬区浅层地下水化学特征及其碳循环意义

对甘肃省灵台县独店镇秋射村黄土剖面浅层地下水的水化学组成、溶解无机碳(DIC)、溶解有机碳(DOC)、颗粒有机碳(POC)等进行了取样分析,对其δ~(13)CDIC和δ~(13)CPOC的特征及其控制因素进行了探讨,并评估了降雨补给过程中的碳酸盐风化碳汇强度。结果表明,研究区地下水的水化学类型为HCO3-Ca·Mg型,其方解石饱和指数SIC大于0,已经饱和,但尚未达到大规模沉淀的程度。研究区黄土浅层地下水的DIC变化范围为5.25~5.45mmol/L,DOC含量为0.59~0.62mg/L,明显低于地表水体;而POC稍高,这是因为黄土颗粒物的混入造成。泉水和井水的δ~(13)CDIC变化范围在-9.19‰~-8.90‰之间,其较高的δ~(13)C与碳酸盐风化-沉积过程中反复的碳同位素交换有关。而δ~(13)CPOC变化范围在-19.99‰~-18.87‰之间,与黄土有机碳同位素特征基本一致。地下水中的HCO-3、Ca2+和Mg2+主要来源于碳酸盐的化学风化。根据风化反应的离子平衡关系,计算得到研究区的风化碳汇为2.82mmol/L,即每有1L的降水入渗到零通量面以下,就会产生2.82mmol的碳汇。     

硅酸锌催化臭氧氧化净水效能连续流实验研究

以实验室制备的硅酸锌为催化剂,考察了在连续流实验中催化臭氧氧化对滤后水水质的影响。结果表明,与单独臭氧氧化相比,在相同实验条件下,硅酸锌的存在能够提高水体中的臭氧浓度。硅酸锌催化臭氧氧化对滤后水的总有机碳(TOC)和天然有机物的去除效果均好于单独臭氧氧化。连续运行10 h,硅酸锌催化臭氧氧化系统中TOC的去除效果稳定,并且Zn2+的溶出非常少。生物可同化性有机碳(assimilable organic carbon,AOC)的测定结果表明,经过硅酸锌催化臭氧化处理后,滤后水中的大分子有机物所占比例明显降低,小分子有机物含量增高。GC-MS分析结果表明,单独臭氧氧化可使滤后水中有机物的种类从41种减少到27种;而硅酸锌催化臭氧化效果明显优于单独臭氧氧化可以使水中有机物种类减少到21种。     

Investigation of microbial safety of a full-scale ozonation and biological activated carbon process under high humidity and temperature conditions

Microbial safety of a full-scale ozonation and biological activated carbon (BAC) process was investigated by examining pathogens, microbial community and particle counts, with emphasis on the BAC effluent. The process is located at South China, where the average humidity and air temperature were 70-80% and 22-24 °C, respectively. A high diversity of microbial community existed on the BAC media. Three types of dominant bacteria were identified, including Chryseobacterium indologenes, Bacillus brevis and Pseudomonas stutzeri, accounting for 90-95% of total bacteria number. As to pathogenic bacteria and viruses, an opportunistic pathogen, Bacillus cereus, was detected on the BAC. Six types of invertebrates were also observed on the medium, including rotifer, cyclops, nematode, clodecera, nauplius and blood worm. Diversity and number of invertebrates in the BAC effluent were higher than those in the BAC influent. Particle counts were generally less than 50 CNT/mL, with the maximum of 500 CNT/mL during the initial filtration stage after backwashing.     

Synergistic effect of biological activated carbon and enhanced coagulation in secondary wastewater effluent treatment

The use of secondary wastewater effluent (SWWE) is an essential strategy for making better use of limited water resources. However, a wide range of organic compounds eventually renders them unsuitable for recycling. In water treatment processes, biologically activated carbon (BAC) is adopted after physicochemical treatment. However, the effectiveness of such combination for SWWE remains poorly understood. This study investigates the effectiveness of various combinations: BAC/enhanced coagulation (EC) or EC/BAC, especially in terms of dissolved organic carbon (DOC) removal. The results showed that distinct advantage could be obtained by adopting BAC/EC combination rather than EC/BAC, as microbes in BAC not only remove non-coagulable compounds but also synergize the removal efficiency by releasing some coagulable humic substances.     

Dissolved organic matter from agricultural fields in the irrigation period.

The aim of this study was to quantify and characterize the dissolved organic carbon (DOC) of paddy fields and crop fields in Tottori, Japan. Dissolved organic carbon (DOC) and ultraviolet (UV) absorbance was measured for the filtrated water of each samples. DOC concentration and SUVA (specific UV absorbance) of biodegradation analysis samples were determined around 50 days after the incubation. In the Fukui paddy fields, DOC concentration varied seasonally from 1.1 to 10.1 mg.Cl(-1), showing higher concentration in heavy runoff of non-agriculture period in April. However, DOC concentration variation did not always correspond to rainfall. The Obadake paddy fields also showed a similar pattern with Fukui paddy fields. The daily DOC discharge per area in Fukui (up), Fukui (down), Obadake (south), Obadake (north) paddy fields influent from paddy fields were 0.02, 0.0161, 0.0135 and 0.0027 kg.a(-1).day(-1), respectively. These differences resulted from differences in agricultural types and customs of farmers according to paddy fields and fields. Also, SUVA (an indirect means to evaluate humic substances (hydrophobic fraction)) of the studied influent waters from paddy fields were generally lower than the influent waters from crop fields. The non-biodegradable DOC accounted for 50.2-98%, 46.8-85.5% of the total DOC in the paddy fields and crop fields.     

Performance evaluation of physicochemical processes for biologically pre-treated livestock wastewater.

The use of a combination of biological and physicochemical methods is a promising technique to reduce highly concentrated pollutants in livestock wastewater: firstly, biodegradable organic matters, nitrogen and a part of phosphorus should be removed in a biological treatment process and then residual non-biodegradable organic matters, color and phosphorus be eliminated by physicochemical methods. In this study, therefore, the integrations of chemical coagulation, activated carbon adsorption, Fenton oxidation and ozonation were evaluated to provide an appropriate post-treatment process for biologically pre-treated livestock wastewater. With applying a single method such as coagulation and Fenton oxidation, a yellowish brown color and COD still remained. According to the experimental result, the quality of treated wastewater including color was enough to be discharged after chemical coagulation followed by ozonation or Fenton oxidation process. Among these, ozonation was the most effective technology for decolorization. Neither simple biological nor physicochemical process provides an adequate treatability for the sufficient depletion of organics and decolorization when treating livestock wastewater. Considering only the removal efficiency, the integration of Fenton oxidation and ozonation would be an efficient alternative as a post-treatment.     

Estimates of the remineralization and burial of organic carbon in Lake Baikal sediments

Sediment cores collected from several stations throughout Lake Baikal in water depths from 100 m off the Selenga River delta to the deepest basin of the lake (~1640 m), have been analyzed for sedimentary organic carbon, nitrogen, and the remineralized components in pore water. The organic carbon content of surface sediments generally varied from 2.3 to 3.2% by weight, and profiles typically showed an exponential decrease in both organic carbon and nitrogen in the upper 20–30 cm of the sediment column. Steady state models of organic matter diagenesis yield first order decomposition rate constants which range from 0.0009 to 0.022 y⁻¹. The calculated residence times for the metabolizable fraction of the organic matter in these sediments increases roughly with increasing water depth and is on the order of 50–300 years. Pore water concentration profiles were determined for dissolved inorganic carbon, dissolved organic carbon (DOC), methane, and dissolved ammonium. At depth (25–30 cm) methane concentrations ranged from 50 to 800 μmol L_pw⁻¹ and DOC from 400 to 900 μmol L_pw⁻¹. Estimation of carbon recycling rates based upon diffusion along pore water concentration gradients at the sediment-water interface, indicate that combined DOC and methane fluxes generally contribute <15% of the overall turnover of sedimentary organic carbon. Comparisons to Laurentian Great Lakes environments show trends in sediment deposition, organic matter remineralization, and the time scales of carbon recycling across nearly two orders of magnitude with the fraction of organic content buried generally decreasing with decreasing sedimentation rates.     

Control of disinfection byproduct formation in Feng-Shan reservoir by the traditional treatment processes plus O3-pilot-plant test.

Two processes in the pilot plant were studied and compared to reduce the disinfection byproduct risk of the potable finished water of Feng-shan treatment utility in Taiwan. For 5 months study, two processes have both demonstrated to achieve a significant removal on the organic precursors of DBPs, including NPDOC and A-254. With the analysis of molecular weight distribution of organics in raw water, the study found the post ozonation plus BAC can provide additional enhancement in degrading organic contents. A process of coagulation/sedimentation/rapid sand filtration/post ozonation/BAC would be suggested as the advanced treatment process improving the supply quality of Feng-shan utility.     

Use of sediment elemental and isotopic compositions to record the eutrophication of a polymictic reservoir in central Texas, USA

Paleolimnological studies are rarely performed on reservoirs because of concern that sediments might not accurately chronicle reservoir history. Eutrophication indicators might behave differently in polymictic reservoirs and stratified natural lakes because of system and/or mixing regime differences. Particulate organic carbon (POC), particulate organic nitrogen (PON), and total phosphorus (TP) concentrations, carbon:nitrogen (C:N) and nitrogen:phosphorus (N:P) ratios, and carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes from a sediment core were measured to demonstrate that sufficient information can be derived from sediments to permit a historical reconstruction. The scattered POC data were likely biased by seasonal/annual variability in allochthonous organic matter (OM) loading. The upwardly increasing PON in the sediment core supported historic primary productivity (PP) data, suggesting PON could be a better PP indicator than POC. The upwardly increasing TP documented historic P enrichment. The upwardly decreasing C:N ratio identified an OM source shift from allochthonous to increasingly autochthonous sources with reservoir age. The upwardly increasing N:P ratio implied that N‐fixation rates have increased with reservoir age, to compensate for increasing N limitation as the P loading increased. The δ¹³C decreased as the PP increased with reservoir age producing an atypical relationship compared to stratified natural lakes. The OM source shifts likely biased the δ¹³C–PP relationship, and might weaken δ¹³C‐inferred PP reconstructions in similar reservoirs. The δ¹⁵N increased with reservoir age, likely resulting from dissolved inorganic N (DIN) source changes, rather than nitrate utilization. Watershed urban growth and dairy operation intensification potentially contributed greater loads of isotopically heavy DIN. This study demonstrated that paleolimnology has great potential to assist eutrophication assessment and management efforts in reservoirs.     

An overview of the integration of ozone systems in biological treatment steps.

Despite the well-known potential and performance of combined biological and ozonation processes for wastewater treatment, only few full-scale applications are published. Beside the synergistic effects of such process combination, which lead to oxidation of recalcitrant and inhibitory compounds or intermediates by enhancement of their biodegradability, the key for raising applicability is the improvement of the ozonation efficiency. An overview about the history and progress of full-scale applications, which deals with combined ozonation and biological treatment is given. Recently more than 40 applications exist, but many of them are not published. Therefore, a couple of selected not yet published applications have been mentioned in this paper. Landfill leachate and industrial wastewater treatment were mostly applicated, while treatment of municial wastewater treatment plant (WWTP) effluents are of increasing interest due to several advantages such as disinfection, decolourisation and removal of persistent dissolved organic carbon (DOC) for water re-use and groundwater recharge.     

臭氧生物活性炭技术的工艺设计与运行管理

针对臭氧生物活性炭工艺应用中的关键问题,首先对工艺设计中的活性炭滤料选择、活性炭滤层结构设计、活性炭滤池选择、臭氧系统选择、臭氧接触池优化设计和复合预氧化设计等内容进行了分析和总结.然后对运行中存在的微生物安全性、大型微生物控制、活性炭滤池初滤水管理及pH控制、预臭氧和主臭氧工艺的运行管理等问题进行了总结,并提出了相应的解决方案.最后,建议今后应重点注意微生物安全性、臭氧副产物控制和工艺运行控制标准等问题.     

Classification of algogenic organic matter concerning its contribution to the bacterial regrowth potential and by-products formation

The bacterial regrowth potential (BRP) and the by-products formation potential after the disinfection (DBP) are parameters recognized to be influenced by the origin of organic matter dissolved in water. A significant difference of the impact of humic compounds and algogenic organic matter (AOM), characteristic for raw waters from reservoirs, to both parameters can be assumed. In systematic laboratory experiments the influence of AOM on the BRP as well as DBP was examined. Different fractions of the AOM were chlorinated and treated with chlorine dioxide. In addition to that the influence of the ozonation was investigated. To assess the biodegradable fraction of the organic matter (BDOC) a large spectrum of byproducts (aldehydes and keto-acids) was analyzed. The BRP in the water was determined by the measurement of the increase of biomass in the water samples. It could be proved, that the chlorination of intact algae cells containing waters may cause a significant increase of the biodegradability in the water if the residual chlorine is totally required. In the case of the disinfection of the AOM containing waters with chlorine dioxide the relative increase of the BRP was lower in comparison to the chlorinated waters. The preozonation of the algae containing waters indicates an additional increase of the BRP, but only by ozonadon of the algae cells. The ozonation of the algae metabolites does not influence the BRP, but it causes a significant decrease of the THIvI-formation if chlorine is used for disinfection.     

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%。     

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.