粉末活性炭回流高密度沉淀池生物强化作用研究

研究了投加粉末活性炭并回流泥炭后高密度沉淀池对有机物的去除效果。结果表明:粉末活性炭回流后有机物的去除效果显著提高:CODMn平均去除率为43.66%,比未投加粉末活性炭工况的32%提高了近12个百分点,沉淀池出水平均CODMn为3.46mg/L,比未投加粉末活性炭时的4.13mg/L降低了约0.7mg/L;对比投炭前后沉淀池中底泥的微生物好氧速率,发现其微生物量的提高与有机物去除效果的变化一致,投加粉未活性炭提高了污泥中微生物量从而提高了有机物的去除率;通过GC-MS对半挥发性有机物的检测发现,投加粉末活性炭后的吸附作用对有机物的浓度有很好的去除效果但对有机物种类去除效果有限,而投炭后吸附以及随着投炭产生的微生物强化作用对有机物种类和浓度都有很好的去除效果。     

高效去除有机物沉淀工艺中试研究

针对地表水有机物污染较重,深度处理单元负荷过高或地表水有机物污染较轻,建设深度处理单元投资过大的问题,提出一种高效去除有机物的沉淀工艺。其以高密度沉淀池为载体,粉末活性炭吸附去除有机物为手段,利用污泥回流对粉末活性炭的富集和回收作用,延长粉末活性炭在沉淀池中的停留时间,充分发挥活性炭的吸附能力,强化对有机物的去除效果。研究结果表明,该工艺相比不投加粉末活性炭的高密度沉淀池,CODMn去除率提高了17个百分点。相比于沉淀池普通活性炭投加方式,在相同去除率的情况下,粉末活性炭投加量减少了68%,节约了运行成本。     

PDF技术在饮用水深度处理中的应用研究

本课题采用粉末活性炭和硅藻土过滤技术,简称PDF技术,对自来水进行深度处理,试验结果表明: 1.粉末活性炭吸附速度极快,故吸附时间对有机物去除效果影响较小; 2.原水中颗粒粒径大小对过滤周期的影响远大于颗粒浓度的影响;同时,附加剂中颗粒粒径分布的均匀性对过滤周期的影响很大; 3.预涂剂中投加适量的混凝剂,对过滤周期具有良好的改善作用; 4.PDF技术可以取得稳定的有机物去除效果。试验表明:粉末活性炭投加量为60mg/L时,COD_(Mn)平均去除率为为60％左右,UV_(254)平均去除率为90％以上。对三氯甲烷、四氯乙烯的去除率分别为61.61％和84.26％; 5.PDF技术在过滤过程中不存在微生物滋长的问题。     

强化传统工艺处理微污染水源水的试验研究

作者采用净水药剂或材料与传统工艺的强化组合工艺处理微污染水源水,试验表明:三种强化组合工艺不同程度地提高了传统工艺去除有机物的能力,其中粉末活性炭组合工艺的去除效果最佳;传统工艺出水中仍含有一定量的有机污染物和致突变物质,严重影响了饮用水的安全性;颗粒活性炭及粉末活性炭组合工艺均能明显减少原水中的有机污染物及致突变活性;高锰酸钾组合工艺不能有效去除水中有机污染物,其出水的致突活性明显高于传统工艺出水.因此,对于微污染水源水中有机污染物及其致突变活性的控制,颗粒活性炭与粉末活性炭组合工艺是有效可行的.     

压力强化混凝沉淀过滤除藻工艺中藻毒素去除研究

为了探究压力强化混凝沉淀过滤除藻工艺中藻毒素的去除效果,试验对比研究了预加压和预氧化后的含藻水,经混凝沉淀、粉末活性炭吸附后的藻毒素去除效果,考察了不同粉末活性炭投加点及投加量对藻毒素去除效果的影响。结果表明,含藻水加压后混凝沉淀,藻类和浊度物质去除效果最优,蓝藻去除率达到96.2%,浊度降至0.49NTU。含藻水在加压和高锰酸钾预氧化后,水中藻毒素浓度未增加,而次氯酸钠预氧化后水中藻毒素浓度最大增幅为215.78%;对于加压水样,在混凝剂投加前30min或投加后7min投加粉末活性炭效果较好,粉末活性炭投加量为5~20 mg/L时,沉淀水藻毒素平均去除率分别达54.13%和53.57%,而与混凝剂同时投加则效果不佳。对次氯酸钠预氧化的水样,粉末活性炭与混凝剂同时投加时效果最好,沉淀水藻毒素平均去除率15.84%。     

水中全氟化合物的活性炭吸附特性研究

针对5种具有不同碳氟链长度的全氟羧酸,选择了4种不同基质的活性炭,开展了活性炭吸附水中全氟羧酸污染物特性的研究。在试验所使用的4种活性炭中,以椰壳和木材为基质的活性炭对全氟羧酸的吸附能力最强。通过水磨法将粉末活性炭制备为超微粉末活性炭(粒径约为1.2μm)后,其吸附容量没有明显变化,仅吸附效率得到了显著提高,在吸附开始的5min内即能够达到吸附平衡。碳氟链长度与活性炭吸附水中全氟羧酸的效果密切相关,全氟羧酸的碳氟链长度越长,其亲水性越弱,活性炭对其的吸附效果越好。当水中pH和离子强度分别为7.2和0.02时,15mg/L的椰壳活性炭能够吸附90%初始浓度为500ng/L的全氟辛酸,但仅能去除水中不高于10%的全氟丁酸。根据试验结果,较低的pH有利于全氟羧酸的活性炭吸附,水中的离子强度与可溶性有机物能够抑制全氟羧酸的吸附去除。     

饮用水深度净化工艺现场对比试验

考察了实际生产规模的臭氧粒状活性炭工艺以及小型超滤、纳滤、反渗透膜法两种典型饮用水深度净化工艺的处理效果。试验结果发现臭氧活性炭工艺具有优良、稳定的去除有机污染物功能,而孔径较小的活性炭纤维除污染效果并不好,臭氧氧化出水、超滤出水再用压缩活性炭进行吸附处理对有机物的去除效率要比直接处理原水高。超滤膜除有机物效率不高,而反渗透和纳滤膜在较好地去除水中有机物的同时,也去除了水中绝大部分无机物,出水有机物和无机物浓度都比较低。     

膜组合工艺处理高藻水的试验研究

针对太湖高藻的水质特点,研究膜处理工艺应对高藻的能力及其缓解膜污染的效果。太湖水有机物主要来源于藻类的新陈代谢产物,而且悬浮颗粒性有机物所占比例较高。试验结果表明,膜以及膜组合工艺可有效去除浊度、藻类和有机物。单独采用超滤膜可造成严重的膜污染,但采用化学强化反洗措施仍可保证膜过滤的稳定运行。采用混凝和粉末活性炭作为预处理可以有效去除有机物和缓解膜压差的上升。对膜污染机理的研究表明,预处理可有效去除大分子有机物,从而有效缓解可逆污染;但对中小分子有机物的去除效果有限,很难有效抑制不可逆污染。导致不可逆污染的主要污染物是强疏水和中性亲水组分。     

生物活性炭长期运行的水质变化特征

考察以太湖为原水的生物活性炭出水水质的长期变化.研究表明,出水的BDOC最低时,可作为生物活性炭进入生物膜阶段的水质表征.在生物膜阶段,吸附和生物降解共同发挥去除有机物的作用,BDOC和NBDOC的去除一直呈下降趋势.生物活性炭运行5～6年后,仅依靠生物膜降解有机物,吸附作用完全消失,此时去除30％的进水BDOC以及10％的小分子有机物.荧光响应的有机物主要依靠活性炭的吸附去除.活性炭对亲水性有机物的去除增强,而对疏水性有机物去除减弱.进一步提出了描述生物活性炭出水水质变化的数学模拟公式.     

高锰酸钾—粉末活性炭工艺在净水厂应急处理中的应用研究

通过静态试验考察了单独投加粉末活性炭、高锰酸钾的不同投量、投加顺序以及两者联用时的投加顺序对去除水体中有机物的影响。结果表明:单独投加粉末活性炭的最佳投加位置是混凝后1min,联用时粉末活性炭的最佳投加位置是与锰同时投加。两者同时投加能够有效去除水中的有机物并降低浊度,可作为原水的应急处理方法。     

石灰软化法处理地下水源水硬度试验研究

采用石灰软化法处理某地下水源水硬度,结果表明,当石灰投加量为220mg/L,pH为8.7～8.9时,可使原水硬度和碱度分别由300mg/L和250mg/L降至115mg/L和80mg/L以下,去除率分别为61.7%和68%,沉淀和过滤对硬度去除效果影响不大;投加石灰后出水浊度明显升高,投加PAC(聚氯化铝)40mg/L,并与常规工艺联用,可使出水浊度稳定降低至0.15～0.65NTU;试验证明"石灰+PAC+常规工艺"能有效去除水中硬度和浊度,出水煮沸后不再生成沉淀和悬浮物,符合现行《生活饮用水卫生标准》(GB 5749—2006)和用户使用要求,石灰软化法药耗成本估算为0.246元/m3。     

Removal of micropollutants in municipal wastewater treatment plants by powder-activated carbon

Micropollutants (MP) are only partly removed from municipal wastewater by nutrient removal plants and are seen increasingly as a threat to aquatic ecosystems and to the safety of drinking water resources. The addition of powder activated carbon (PAC) is a promising technology to complement municipal nutrient removal plants in order to achieve a significant reduction of MPs and ecotoxicity in receiving waters. This paper presents the salient outcomes of pilot- and full-scale applications of PAC addition in different flow schemes for micropollutant removal in municipal wastewater treatment plants (WWTPs). The sorption efficiency of PAC is reduced with increasing dissolved organic carbon (DOC). Adequate treatment of secondary effluent with 5-10 g DOC m(-3) requires 10-20 g PAC m(-3) of effluent. Counter-current use of PAC by recycling waste PAC from post-treatment in a contact tank with an additional clarifier to the biology tank improved the overall MP removal by 10 to 50% compared with effluent PAC application alone. A dosage of 15 g PAC m(-3) to a full-scale flocculation sand filtration system and recycling the backwash water to the biology tank showed similar MP elimination. Due to an adequate mixing regime and the addition of adapted flocculants, a good retention of the fine fraction of the PAC in the deep-bed filter were observed (1-3 g TSS m(-3); TSS: total suspended solids). With double use of PAC, only half of the PAC was required to reach MP removal efficiencies similar to the direct single dosage of PAC to the biology tank. Overall, the application of PAC in WWTPs seems to be an adequate and feasible technology for efficient MP elimination (>80%) from wastewater comparable with post ozonation.     

强化混凝技术处理南淝河污染水的效果

选用聚合氯化铁(PFC)、聚合硫酸铁(PFS)、聚合氯化铝(PAC)和聚合氯化铝铁(PAFC)作为混凝剂;选用阳离子型聚丙烯酰胺(CPAM)、阴离子型聚丙烯酰胺(APAM)和非离子型聚丙烯酰胺(NPAM)作为助凝剂,通过室内试验对比研究强化混凝技术中多种混凝剂单用及其和助凝剂联用对南淝河污染水的除浊和去污效果,并用于南淝河现场构建的混凝沉淀系统。结果表明,4种混凝剂单用时,PAFC对浊度、TP去除效果最优,对CODMn有良好的去除效果,且不影响原水的p H值,而PFC和PFS单用时可明显降低原水p H值,4种混凝剂单用时对TN均没有明显去除效果;PAFC与CPAM联用时对浊度的去除效果最佳,明显优于PAFC与APAM和NPAM联用和PAFC单用的效果;混凝剂与CPAM联用提高了其除浊和去除TP的能力,但不能明显改善其去除CODMn的效果,对原水p H和TN的影响与单用时相同。选取"PAFC+CPAM"作为南淝河示范工程的混凝剂和助凝剂,现场混凝沉淀出水水质稳定,浊度和TP的去除效果较好,去除率分别达到90%和80%,对CODMn的去除率约为52%,而对TN的去除效果有限,去除率约为22.4%。     

Rapid adsorption pretreatment with submicrometre powdered activated carbon particles before microfiltration.

Manufacturer-supplied powdered activated carbon (PAC) was ground to produce submicrometre particles (0.8 and 0.6 m median diameter) for use as an adsorbent before microfiltration (MF) for drinking water treatment. Batch tests revealed that the microground PAC adsorbed natural organic matter (NOM) much more rapidly and had a higher adsorptive capacity than ordinary PAC. The water samples pretreated with the submicrometre PAC were subjected to MF, and the results of experiments with different PAC contact times revealed that a 1 min retention time was sufficient for adsorptive removal of NOM. The use of submicrometre PAC permitted not only shorter PAC contact times but also a 75% reduction in dose.     

净水厂应对突发乙苯污染的应急处理中试研究

乙苯是净水厂原水突发水质污染的高风险物质之一.通过中试研究了应对原水突发乙苯污染的应急处理工艺.结果表明,常规工艺难以去除水中乙苯,向原水中投加粉末活性炭(PAC)与强化常规工艺联用可有效去除水中乙苯,保证处理后水质达到《生活饮用水卫生标准》(GB 5749-2006)要求;PAC与原水混合阶段是乙苯去除的主要阶段,去除率为78.9％～97.4％,强化常规工艺可进一步去除水中低浓度乙苯,颗粒活性炭滤柱作为安全余量,是水质安全保障的最后关口.基于中试结果,给出了应对原水突发乙苯污染时PAC对乙苯的吸附能力.     

Performance improvement of hybrid membrane bioreactor with PAC addition for water reuse.

A study was carried out on a hybrid (AS-SBF) membrane bioreactor (HMBR) for the municipal wastewater reclamation and reuse at Chengfengzhuang WWTP in Daqing City, Heilongjiang Province. It was found that the effects of DO and water temperature on performance of the HMBR was significant. Under the conditions of water temperature in range of 10-14 degrees C, pH of 6.6- 7.0, DO of 4-6 mg/l and HRT of 7 h, the HMBR exhibited removal efficiencies for CODcr, BOD5, NH3-N and TN of 96.7%, 98.9%, 93.7% and 60.5% respectively. The turbidity of effluent from HMBR was below 1 NTU. The effluent of HMBR meets the standard of wastewater reclamation for oil exploitation. PAC was added into the bioreactor at the second operating stage, in order to further research parameters variation. The flux was improved by 53.2%, compared to the membrane without PAC-addition, due to formation of a PAC pre-coat layer on the membrane surface, with lots of advantages such as larger granules, higher porosity, non-compressibility, higher filterability and easy removal, compared with pure biomass layer. In addition, the performance of HMBR was further improved, due to adsorption and degradation of SMPs, the average removal of CODcr and TN was further improved by 5.1% and 13.5% respectively. Biomass in the HMBR was quantitatively measured, of which the biofilm played a major role in pollutants removal.     

Application of chemical precipitation for piggery wastewater treatment.

Several series of experiments were conducted to investigate the treatment of piggery wastewater using chemical precipitation (CP) where various types of coagulants such as aluminium sulfate (Al2(SO4)3), poly aluminium chloride (PAC), ferric chloride (FeCl3), ferric sulfate (Fe2(SO4)3), ferrous sulfate (FeSO4) and ferrous chloride (FeCl2) were used. Throughout the experiments, CP was found to achieve high removal efficiencies for organic compounds and nutrients (nitrogen and phosphorus) from the piggery wastewater. Experimental results showed the optimal doses of FeCl3, Fe2(SO4)3, FeCl2 and FeSO4 was 2.0 g/L, while 0.31 g/L and 2.5 g/L were the optimum dose for PAC and Al2(SO4)3, respectively. The pH range 4-5 resulted in the best performance to all coagulants except FeCl2 and FeSO4, whose optimum pH were more than 6. Percentage removal efficiencies for COD were in the ranges of 70-80%, 90-95% for SS, 80-90% for organic-N and TP. Those removal efficiencies were achieved within 5 min of operation. Three times of repetition in CP resulted in higher removal efficiencies for COD, SS and colour up to 74%, 99% and 94% respectively, in which Al2(SO4)3 was used as the coagulant. Removal efficiencies of various water quality parameters in a continuously operated reactor were similar to those of the batch experiments. Biodegradable ratios (BOD5/COD) increased up to 65% after the application of CP.     

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.     

混凝-气浮-过滤工艺中粉末活性炭投加效果与投加点研究

对投加粉末活性炭(PAC)预处理黄河原水进行了现场中试研究,确定了PAC适宜的投加位置和投量。结果表明,PAC最佳投加点为混合池,投加PAC使气浮出水浊度提高0.4NTU左右,滤后出水浊度略有升高(<0.1NTU);在絮凝池投加会造成气浮、过滤出水浊度的明显增加;在预氧化前投加PAC较之在混合池投加其有机物去除率略有下降;在混合池投加,当PAC的投加量为10mg/L时,滤后水的CODMn去除率提高15%-20%,可取得满意的结果;滤后水的色、臭和味等指标可完全达到国家饮用水标准的要求。     

The removal of residual organic matter from biologically treated swine wastewater using membrane bioreactor process with powdered activated carbon.

The objective of this study was to characterize the mechanisms of the COD removal in the membrane bioreactor (MBR) process with powdered activated carbon (PAC) addition and to determine its optimal operation, for the removal of residual organic matters (ROM) from biologically treated swine wastewater. The MBR process with PAC showed higher removal efficiency of chemical oxygen demand (COD(Mn)) than that without PAC. When the average COD(Mn) concentration of the influent was 217 mg/L, the average COD(Mn) concentration of the permeate from the MBR with PAC was about 41.5 mg/L, indicating an approximate removal efficiency of 81%. On the other hand, the average COD(Mn) concentration of the permeate from the MBR without PAC was 172 mg/L. The PAC dosage estimated to obtain the above removal efficiency was about 0.74 g per litre of influent. Among the total residual organics removed by PAC-added MBR, 46.5% was removed by PAC adsorption, 20.8% by biodegradation, 4.4% by membrane separation, and 9.3% by enhanced microorganism activity. From these results, the MBR process with PAC was considered as a very useful treatment process for the reduction of COD(Mn) in biologically treated swine wastewater.