PPC预氧化和超滤协同处理引黄水库高藻水

采用高锰酸盐复合药剂(PPC)预氧化—混凝—沉淀—超滤组合工艺处理黄河下游引黄水库夏秋季节高藻水。工艺优化试验结果表明:当处理高藻水时,聚氯化铝最佳投加量为4mg/L,PPC最佳投加量为0.6mg/L。进行了混凝—沉淀—超滤和PPC预氧化—混凝—沉淀—超滤工艺中试比较,结果表明:两种工艺均能将出水浊度控制在0.1NTU以下;投加0.6mg/LPPC能使组合工艺对原水UV254和藻类的平均去除率分别提高10%和28%。将PPC预氧化技术和超滤技术联用,具有协同除污染作用,降低进入膜表面的污染负荷,缓解膜污染。     

强化混凝技术处理东太湖原水研究

在常规混凝工艺确定的最佳处理条件下,考察了单独高锰酸钾(KMnO4)和次氯酸钠(NaClO)预氧化、单独投加粉末活性炭(PAC)以及KMnO4和PAC联用对混凝处理东太湖原水的强化效果。结果表明,聚氯化铝和硫酸铝的最佳投加量分别为20mg/L和30mg/L,聚氯化铝的混凝效果明显优于硫酸铝;投加KMnO4对浊度、CODMn和UV254的去除均有一定程度提高,但不利于原水氨氮的去除;投加PAC有显著的强化混凝作用,各指标去除率均有所提高;KMnO4和PAC联用能进一步提高水中UV254的去除率;预氧化大大提高了混凝对氨氮的去除效果,投加1mg/L NaClO对氨氮去除率可达100%。     

五种预处理方式对超滤膜处理松花江水的效能比较

采用中试对比考察了不同预处理方式(包括混凝、砂滤、混凝-砂滤、高锰酸钾-混凝-砂滤、粉末活性炭)对超滤膜渗透性能及其对去除松花江水中污染物的影响.结果表明:以松花江水为原水,在超滤膜之前进行预处理是必要的.其中单独混凝会使膜通量降低,投加高锰酸钾使膜通量显著增加,并可延缓膜通量的下降速度,投加粉末活性炭对提高膜通量作用不大;不同预处理均能保证超滤膜出水浊度低于O.3 NTU,大于2 μm颗粒数少于10个/mL;此外,不同的预处理均能提高超滤膜对水中有机物的去除效果,高锰酸钾-混凝-砂滤-超滤对DOC、UV254的去除率分别为37.5%、28%.     

粉末活性炭一混凝联用工艺强化去除毒死蜱试验研究

针对受毒死蜱污染的水源水,通过小试研究了粉末活性炭(PAC)-混凝联用工艺对毒死蜱的去除效果.结果表明混凝工艺对毒死蜱具有一定的去除效果,但当原水中毒死蜱浓度较高时,混凝后毒死蜱浓度高于《生活饮用水卫生标准》 (GB 5749-2006) 30 μg/L的限值,因此为使出水达标还需增加PAC吸附处理措施;针对原水中不同初始浓度的毒死蜱(超标5～50倍),调节PAC投量(10～60mg/L),吸附30 min后,再投加30mg/L聚氯化铝,经PAC-混凝联用工艺处理后出水中毒死蜱浓度小于30 μg/L,满足《生活饮用水卫生标准》要求.PAC-混凝联用工艺可以作为水源水突发毒死蜱污染时的应急处理措施.     

在线混凝-超滤联用工艺用于小城镇给水的应用研究

采用在线混凝-超滤联用工艺对某水塘水进行中试研究.试验结果表明,将常规处理作为超滤的预处理时,膜压差增加迅速,无法保持稳定运行.将在线混凝作为超滤的预处理时,膜压差增加缓慢.通过比较不同的混凝剂抑制压差和去除有机物的效果,发现聚硫酸铁均优于聚氯化铝.次氯酸钠和高锰酸钾预氧化的试验结果表明,尽管高锰酸钾去除有机物和三氯甲烷生成潜能的效果较好,但膜压差增加较快.在线混凝-超滤联用工艺处理后出水的CODMn可低于3 mg/L.     

接触过滤-活性炭吸附-超滤一体化净水装置处理长江原水的研究

试验采用接触过滤-活性炭吸附-超滤工艺处理长江原水.结果表明,接触过滤能有效地去除较大悬浮物,活性炭能吸附水中大量有机物,有效防止膜污染.并且用0.4%的HCl和0.4%的NaOH对膜进行化学清洗,能使膜的过滤性能得到很好的恢复.当原水平均浊度为114.8 NTU、氨氮为0.35 mg/L、TOC为2.47 mg/L、CODMn为2.7 mg/L、细菌数为700 CFU/mL时,工艺出水浊度为0.07 NTU、氨氮为0.09 mg/L、TOC为0.3 mg/L、CODMn为0.88 mg/L、细菌总数为0.     

粉末活性炭—超滤组合工艺处理长江陈行原水

以长江陈行水库原水为研究对象,探讨了粉末活性炭—超滤组合工艺对水中CODMn、UV254、浊度、氨氮等去除效果,评价投加粉末活性炭后超滤膜跨膜压差(TMP)的变化情况.结果表明:超滤膜出水CODMn均值为1.10 mg/L,平均去除率为48.7％,UV254均值为0.016 cm-1,平均去除率为76.2％;组合工艺对水中氨氮具有一定的去除效果,对总铁、总锰去除效果显著,出水浊度保持在0.031 NTU以下.粉末活性炭投加于沉淀池之前,对于改善出水水质、减轻膜污染起到了较好的效果.     

含腐殖酸低浊原水的改性凹土强化混凝效果分析和参数确定

研究了改性凹土联合聚氯化铝强化混凝耦合去除浊度和腐殖酸的效果。试验原水条件为腐殖酸浓度10mg/L,浊度为(30±1)NTU。采用静态混凝搅拌试验,考察了聚氯化铝和改性凹土的混凝沉淀时间、复配投加量、pH、投加顺序、搅拌速率等工艺参数对腐殖酸和浊度耦合去除效果的影响。结果表明,在强化混凝中,当聚氯化铝投加量为15mg/L,改性凹土投加量为30mg/L,沉淀时间30min,pH=7时,腐殖酸和浊度的同步去除率分别达到95.5%和96.8%,对比单投加聚氯化铝混凝工艺,聚氯化铝投加量可降低25%,并减少沉降时间。     

投加活性炭膜污染控制的研究

比较了不同粒径(20～40目、40～60目、80目、100～150目)的活性炭对膜生物反应器减缓膜污染的效果,粒径确定后比较不同投加量(0、1g/L、2g/L)对膜生物反应器膜通量的影响,结果表明:粒径过大或过小都不利于减缓膜污染,本试验适宜的活性炭粒径为40～60目;1g/L的颗粒活性炭膜通量下降比较缓慢,2g/L的活性炭反而会加剧膜污染。活性炭减缓膜污染的主要原因是改善了活性污泥混合液的性能,阻碍污泥层在膜面的形成。     

强化混凝处理微污染原水的试验研究

混凝是水处理的基本工艺之一,如何提高混凝的效率是饮用水处理的关键。以微污染原水中的有机污染物为对象,对比研究了几种强化混凝工艺的技术特征,结果如下:预氧化、粉末活性炭吸附、助凝剂和回流污泥的方式均能强化混凝的效率,有效提升处理过程中的COD_(Mn)、色度去除率;几种强化混凝工艺的机理不同,预氧化强化混凝是通过氧化作用将大分子有机物转化为分子量较小、疏水性较高的有机物;粉末活性炭吸附强化混凝是利用粉末活性炭对特定分子量的有机物的吸附作用;助凝剂强化混凝沉淀是通过助凝剂提高絮体颗粒尺寸,加速颗粒沉降;污泥强化混凝则是利用回流污泥提供混凝反应的凝聚核心的方式提升混凝的效率,提高COD_(Mn)去除率。     

利用溶气气浮工艺强化处理低浊高色富含有机物地表水

低浊高色富含有机物地表水难于混凝,试验采用“混凝-溶气气浮”(“混凝-DAF”)工艺处理此类水,并与常规“混凝-沉淀”工艺进行了比较。结果表明,“混凝-DAF”工艺在较低投药量时能取得更好的处理效果;对于“混凝-DAF”工艺,增大混凝剂投量后出水浊度基本不变,但出水色度及CODMn可进一步降低;“混凝-DAF”工艺去除水中有机物的能力优于“混凝-沉淀”工艺。最后,对“混凝-DAF”工艺去除水中有机污染物的机理进行了探讨。     

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.     

Fluidised pellet bed bioreactor: a promising technology for onsite wastewater treatment and reuse.

A pilot-scale fluidised pellet bed (FPB) bioreactor, which combines chemical coagulation, biological degradation, particle pelletisation and separation in one unit, was applied for onsite wastewater treatment and reuse. As a result of rational use of inorganic coagulant and organic polymer and moderate mechanical agitation, spherical particles were generated in the upflow column and a well-fluidised bed was formed. With a continuous supply of dissolved oxygen through a recycling loop, an aerobic condition was kept in the bottom section of the FPB column. Under such conditions the pellets in the FPB column showed the following characteristics: (1) compact structure and high density; (2) rich in microorganisms; and (3) high MLSS and MLVSS concentrations. Therefore, the FPB bioreactor achieved more than 90% removal of SS, COD, BOD and TP from raw domestic wastewater within a total hydraulic retention time (HRT) of only about 30 minutes. It also showed nitrification and denitrification ability and the TN removal could be about 50% as the recycling ratio was increased to 1:1. The treated water quality is generally competitive with the secondary effluent from a conventional activated sludge process. With these advantages the FPB bioreactor is recommendable as a compact system for onsite wastewater treatment and reuse.     

Lab scale study on electrocoagulation defluoridation process optimization along with aluminium leaching in the process and comparison with full scale plant operation

An excess or lack of fluoride in drinking water is harmful to human health. Desirable and permissible standards of fluoride in drinking water are 1.0 and 1.5 mg/L, respectively, as per Indian drinking water quality standards i.e., BIS 10500, 1991. In this paper, the performance of an electro-coagulation defluoridation batch process with aluminium electrodes was investigated. Different operational conditions such as fluoride concentration in water, pH and current density were varied and performance of the process was examined. Influence of operational conditions on (i) electrode polarization phenomena, (ii) pH evolution during electrolysis and (iii) the amount of aluminium released (coagulant) was investigated. Removal by electrodes is primarily responsible for the high defluoridation efficiency and the adsorption by hydroxide aluminium floc provides secondary effect. Experimental data obtained at optimum conditions that favored simultaneous mixing and flotation confirmed that concentrations lower than 1 mg/L could be achieved when initial concentrations were between 2 and 20 mg/L. pH value was found to be an important parameter that affected fluoride removal significantly. The optimal initial pH range is between 6 and 7 at which effective defluoridation and removal efficiencies over 98% were achieved. Furthermore, experimental results prominently displayed that an increase in current density substantially reduces the treatment duration, but with increased residual aluminium level. The paper focuses on pilot scale defluoridation process optimization along with aluminium leaching and experimental results were compared with a full-scale plant having capacity of 600 liter per batch.     

Membrane bioreactor application within the treatment of high-strength textile effluent

A pilot-scale dual-stage membrane bioreactor (dsMBR) incorporating two ultra-filtration (UF) side-stream membrane modules was designed, constructed, operated and evaluated on-site for treating high-strength textile effluent. The effluent stream was characterised by a COD range of between 45 to 2,820 mg/L and an average BOD of 192.5 mg/L. The dsMBR achieved an average COD reduction of 75% with a maximum of 97% over the 9 month test period. The COD concentration obtained after dsMBR treatment averaged at 190 mg/L, which was well within the discharge standard. The average reduction in turbidity and TSS were 94% and 19.6%, respectively, during the UF-MBR stage of the system. Subsequent treatment of the UF-permeate with nanofiltration (NF) and reverse osmosis (RO) removed both the residual colour and remaining salt. A consistent reduction in the color of the incoming effluent was evident. The ADMI was reduced from an average of 659 to ～20, a lower ADMI and colour compared to the potable water. An average conductivity rejection of 91% was achieved with conductivity being reduced from an average of 7,700 to 693 μS/cm and the TDS reduced from an average of 5,700 to 473 mg/L, which facilitated an average TDS rejection of 92%.     

Influence of type and dose of coagulants on effectiveness of PAH removal in coagulation water treatment

This study evaluated the influence of the type and dose of coagulants on the removal of 16 polycyclic aromatic hydrocarbons (PAHs) in the coagulation process. The effects of coagulant type and dose in reducing water turbidity, colour, and the total content of organic compounds were also assessed. The surface water samples had the turbidity of 9.3–11.2 NTU and colour of 25–35 mg/L. The content of organic compounds determined with total organic carbon (TOC) was 9.2–12.5 mg/L. For the coagulation process, pre-hydrolyzed polyaluminium chloride (PACl) coagulants with basicity values of 41%, 65%, and 85% were used. This shows that water purification performance increased as the basicity of the coagulant increased. When the coagulant with the highest basicity and a dose of 3 mg Al per litre was used, a removal efficiency of 83% in the concentration of benzo(a)pyrene was achieved, and efficiencies for the remaining 15 PAHs ranged from 80% to 91%. These values were 4%–9% higher than those achieved using other coagulants. The removal efficiencies of turbidity, colour, and TOC were 80%, 60%, and 35%, respectively. The water purification performance, including PAH removal, was improved with the increased coagulant dose. Increasing the coagulant dose had more pronounced effects on PAH removal than on the reduction of turbidity and TOC.     

聚合氯化铝铁强化混凝去除藻类试验研究

采用聚合氯化铝铁,对微污染黄河水库水进行了强化混凝除藻试验.试验结果表明:针对原水水质,PAFC的最佳投加量为15mg/L,此时浊度和叶绿素a的去除率分别为94.67%和80.15%;PAFC的最佳pH范围是5.0～9.0,试验过程中无需对原水进行调节pH值;投加高分子助凝剂(JY)对原水的浊度、高锰酸盐指数和叶绿素a有一定的去除效果,助凝剂与混凝剂的复配可改善PAFC的混凝去除效果,助凝剂JY的投加量为0.3mg/L时,叶绿素a的去除率可提高12.9%.     

Comparison of the behaviour of selected micropollutants in a membrane bioreactor and a conventional wastewater treatment plant.

Micropollutants as pharmaceutical active compounds (PhACs), residuals of personal care products or endocrine disrupting chemicals are of increasing interest in water pollution control. In this context the removal efficiencies of sewage treatment plants (STPs) are of importance, as their effluents are important point sources for the release of those substances into the aquatic environment. Activated sludge based wastewater treatment is the worldwide prevalently used treatment technique. In conventional plants the separation of treated wastewater and sludge occurs via sedimentation. A new development is the application of membrane technology for this separation step. The studies focus on the influence of the solids retention time (SRT) on the removal efficiency, as the SRT is the most important parameter in the design of STPs. A conventional activated sludge plant (CASP) and a membrane bioreactor (MBR) were operated at different SRTs. The substances selected are the antiepileptic carbamazepine, the analgesics diclofenac and ibuprofen, the lipid regulator bezafibrate, the polycyclic musks tonalide and galaxolide and the contraceptive 17alpha-ethinylestradiole. No significant differences in the removal efficiency were detected. Due to the absence of suspended solids in the MBR effluent, substances with high adsorption potential could be retained to slightly higher amounts.     

高锰酸盐-聚丙烯酰胺联用强化混凝处理太湖支流原水研究

太湖B支流地表水受水土流失、水体富营养化和环境污染等因素影响,水体污染严重,水中有机物浓度和藻密度相对较高。常规的"混凝—沉淀—砂滤—加氯消毒"处理工艺难以有效地去除水中有机物、铁锰、藻类等物质。采用高锰酸盐(PPC)-聚丙烯酰胺(PAM)联用强化混凝工艺对原水进行处理。高锰酸盐投量在0.45 mg/L和聚丙烯酰胺投量在0.07 mg/L条件下联用强化混凝的静态试验结果表明:PPC-PAM联用强化混凝对浊度、色度、铁、锰和耗氧量的平均去除率为90%、73%、92%、99%和38%。PPC在0.3～0.5 mg/L投量和PAM在0.05～0.10 mg/L投量下联用强化混凝生产试验的出厂水浊度、色度、铁、锰等指标,均比历史同期水平要好。     

A pilot study on accelerated sludge degradation by a high-concentration membrane bioreactor coupled with sludge pretreatment.

A new sludge treatment process combining a high MLSS membrane bioreactor with sludge pretreatment techniques was studied in pilot-scale experiments. The membrane bioreactor (MBR) was adopted for high efficiency aerobic digestion. The combination of alkaline-ozone treatment of the mixed liquor in the MBR reactor accelerated the biodegradation process by enhancing biodegradability of the sludge. The hydraulic retention time (HRT) of the reactor was set as 3.1 days and the DO level was 1 mg/L on average. After 5 months of operation, the accumulative total solids reduction was more than 70%. Removal efficiency of volatile solids and non-volatile solids were 76% and 54%, respectively. It was found that a considerable portion of the non-volatile solids was dissolved into ions and then flushed out with the effluent. Also, about 41% and 28% of T-N and T-P in the raw sludge were removed although no biological nutrient removal process was adopted. The experiment was run smoothly without significant membrane fouling, even at the relatively high levels of MLSS concentration (11,000-25,000 mg/L). It is concluded that the newly proposed process can significantly increase the sludge reduction efficiency with much shorter retention times.