粉末活性炭-超滤对城市污水深度处理的试验研究

采用粉末活性炭(PAC)-超滤(UF)的组合工艺对城市二级生化处理出水进行深度处理.研究了粉末活性炭的投加对主要污染物的去除效果和对膜渗透性能的影响.结果表明,UF本身具有良好的截留SS功能和除菌作用.投加PAC对CODcr、BOD5和色度的去除率分别为55.3%,35%和69.7%.同时投加粉末活性炭能有效地提高膜通量,通过反冲洗,膜通量能得到很好的恢复.     

微絮凝-砂滤-超滤处理淮河原水的试验研究

采用微絮凝-砂滤-超滤工艺对淮河原水进行了中试规模的试验．重点考察预处理条件如滤速和混凝剂投加量的变化对后续膜处理性能的影响．结果表明，试验工艺去除CODMn的效果随着混凝剂投加量的增加而提高．在投加量(大于4mg／L)不变的条件下，滤速的变化不会影响砂滤出水的浊度和CODMn，当投加量为4mg／L时，较高的滤速导致砂滤出水的浊度和CODMn的增加．由于后续超滤膜的截留作用，膜出水的浊度和CODMn令人满意．     

高锰酸钾强化混凝/砂滤/超滤组合工艺处理松花江水试验研究

进行中试试验考察了高锰酸钾对混凝/砂滤/超滤组合工艺去除松花江水中污染物的强化效能及对膜渗透性能的影响.结果表明,高锰酸钾可以强化对水中污染物的去除,DOC去除率由21.4%提高到33.4%,UV254去除率由14.2%提高到28.0%,膜出水浊度低于0.1NTU,大于2μm颗粒物少于10个/mL;此外,高锰酸钾可以改善膜渗透性能,延缓了膜通量的降低速率,提高了膜通量.     

超滤膜净化水库水试验研究

用中空纤维超滤膜处理哈尔滨附近B水库水,以替代混凝、沉淀、砂滤的传统自来水生产方法,研究生产饮用水的新工艺.研究了原水温度、浊度、操作压力和混凝剂的加入量对膜通量的影响.研究发现超滤膜通量与膜进水浊度的对数成反比,跨膜压力增大、适当加入混凝剂,膜通量增加.超滤出水和传统工艺的出水进行了比较,超滤膜出水浊度小于0.2 NTU,明显好于传统工艺的出水浊度.对超滤处理后的出水水质进行了全分析,超滤对铁、铝、锰、色度、好氧量、总有机碳等均有较好的处理效果,完全满足饮用水水质的标准.     

不同混凝剂对污水处理厂出水的深度处理研究

城市生活污水处理厂出水经过处理后作为中水回用生产过程对于节水具有重要意义。针对某生活污水处理厂出水回用于电厂循环水系统的目的,研究不同混凝剂的混凝处理效果。结果表明,四种混凝剂对应的处理效果依次为PAC>硫酸铝>PFS>硫酸亚铁。PAC的混凝效果最好,在投加量为25mg/L时,可以使浊度从4.95降低到0.808,去除率可达83.7%。     

硅藻土错流动态膜工艺处理淮河原水的运行特性

采用硅藻土错流动态膜过程直接处理淮河原水,考察商品硅藻土在不同投加量、不同附加剂配合条件下动态膜的成膜效果、出水浊度和膜通量变化.研究结果表明,采用商品硅藻土和聚合氯化铝附加剂动态膜成膜较好;继续在动态膜过滤过程中不断加入0.25 mg/L聚合氯化铝,出水浊度可以稳定在0.25 NTU或以下.错流可以适当延缓硅藻土动态膜通量衰减.     

超滤-反渗透双膜法用于中水回用的中试研究

针对钢铁企业污水处理站出水回用时存在含盐量高的问题,采用超滤-反渗透双膜法对出水进行深度处理.试验考察了武钢污水处理站出水水质对超滤膜通量、跨膜压差和膜面流速的影响,确定了超滤反洗周期,分析了超滤膜的污染情况,经双膜法深度处理后的产水电导率保持在20μS/cm以下,平均除盐率为96.9%.     

混凝-微滤饮用水处理中试装置运行的优化研究

采用300 m3/d中试规模的混凝-微滤膜系统处理饮用水,间歇抽吸的运行方式连续运行,连续监测了系统运行期间的处理效果及膜污染特性,主要考察抽停比和气水比对于混凝-微滤中试装置处理效果及膜通量特性的影响.结果表明,抽停比试验的两个阶段,分别采用8/2、13/2、18/2、28/2作为不同抽停比的对比试验,对于出水水质未出现显著影响,而膜污染会随抽停比的增加略有加强;曝气量试验的两个阶段,分别采用14.9/1、12.8/1、10.6/1、8.5/1的气水比作为不同曝气量的对比试验,对于出水水质以及膜污染情况均未出现显著影响;化学清洗过程中,采用盐酸、氢氧化钠和次氯酸钠为清洗药剂,选用不同的清洗步骤对清洗效果影响不大.化学清洗后膜池的膜比通量并没有得到完全的恢复.     

硫酸铝混凝条件的变化对膜分离特性的影响

考察在混凝-膜分离处理中，混凝条件如投加量和pH的变化对膜分离的特性的影响．试验表明，混凝条件的变化会影响矾花的尺寸大小和表面的Zeta电位，因而对膜过滤阻力有较大的影响．适当的投加量能形成较大的矾花，使滤饼层阻力较低；过量的投加形成较小的矾花，使滤饼层阻力较大．当矾花表面的Zeta电位与膜表面的电位相同时，滤饼层阻力较低，相异时，滤饼层阻力较大．试验表明，不存在某种最佳的混凝条件满足最大限度地去除有机物的同时使滤饼层阻力最低．     

某厂生活污水站出水用UF膜过滤的污染试验研究

对UF膜处理某厂生活污水出水时膜污染的机理进行了研究．实验结果表明，在膜过滤过程中，沉积层的形成是膜污染的主要来源．压力越大，沉积阻力所占总阻力比例越大．投加混凝剂后沉积阻力所占总阻力比例下降．同时，过滤总阻力也显著减小．膜过滤原水初期，膜污染过程不受堵塞的控制．膜过滤原水过程符合沉积过滤定律．混凝后膜过滤初期，截留分子量为3万的UF膜污染过程不受堵塞的控制，而10万和14万UF膜过滤混凝出水初期时膜污染过程虽然受堵塞的控制，但时间很短，混凝后膜过滤过程主要受沉积层的控制．     

浸没式超滤膜处理地表水除污染效能试验研究

进行中试实验考察了浸没式超滤膜处理地表水的除污染效果.实验结果表明:膜出水的浊度恒低于0.10 NTU;膜出水的CODMn值为2.34~3.12 mg/L;膜出水中大于2μm的颗粒总数为11~20个/100 mL;膜出水中未检测出细菌;短周期内的气水反冲洗并排空,可以使膜运行压力在一定程度上得以恢复.     

Removal of bromide by aluminium chloride coagulant in the presence of humic acid

Bromide can form disinfection by-products (DBPs) in drinking water disinfection process, which have adverse effects on human health. Using aluminium chloride as a model coagulant, removal of bromide by coagulation was investigated in the absence or presence of humic acid (HA) in synthetic water and then was conducted in raw water. Results demonstrated that in synthetic water, 93.3-99.2% removal efficiency of bromide was achieved in the absence of HA with 3-15 mg/L coagulant, while 78.4-98.4% removal efficiency of bromide was obtained in the presence of HA with the same coagulant dosage and 86.8-98.8% HA was removed simultaneously. Bromide in raw water was removed 87.0% with 15 mg/L coagulant. HA apparently reduced the removal of bromide with low coagulant dosage or at high pH, while minor influence on removal of bromide was observed with high coagulant dosage or at low pH. Thus, bromide could be reduced effectively by enhanced coagulation in drinking water treatment.     

Treatment of palm oil mill effluent (POME) by coagulation flocculation process using peanut–okra and wheat germ–okra

Coagulation–flocculation has been proven as one of the effective processes in treating palm oil mill effluent (POME), which is a highly polluted wastewater generated from palm oil milling process. Two pairs of natural coagulant–flocculant were studied and evaluated: peanut–okra and wheat germ–okra. This research aims to optimize the operating parameters of the coagulation flocculation process in removing turbidity, total suspended solid and chemical oxygen demand (COD) from POME by using a central composite design in the Design Expert^® software. Important parameters such as operating pH, coagulant and flocculant dosages were empirically determined using jar test experiment and optimized using response surface methodology module. Significant quadratic polynomial models were obtained via regression analyses (R²) for peanut–okra (0.9355, 0.9534 and 0.8586 for turbidity, total suspended solids and COD removal, respectively) and wheat germ–okra (0.9638, 0.9578 and 0.7691 for turbidity, total suspended solids and COD removal, respectively). The highest observed removal efficiencies of turbidity, total suspended solids and COD (92.5, 86.6 and 34.8%, respectively, for peanut–okra; 86.6, 87.5 and 43.6%, respectively, for wheat germ–okra) were obtained at optimum pH, coagulant and flocculant dosages (pH 11.6, 1000.1 mg/L and 135.5 mg/L, respectively, for peanut–okra; pH 12, 1170.5 mg/L and 100 mg/L, respectively, for wheat germ–okra). The coagulation flocculation performance of peanut–okra and wheat germ–okra were comparable to each other. Characterizations of the natural coagulant–flocculant, as well as the sludge produced, were performed using Fourier transform infrared, energy-dispersive X-ray spectroscopy and field emission scanning electron microscope. More than 98% of water was removed from POME sludge by using centrifuge and drying methods, indicating that a significant reduction in sludge volume was achieved.     

Recycle of Alum recovered from water treatment sludge in chemically enhanced primary treatment

An investigation was made to study the feasibility of recovering the Alum from coagulation sludges and reusing it in chemically enhanced primary treatment (CEPT) process to make the CEPT more cost-effective and recover the resource (Alum) efficiently. The optimum condition and efficiency of the acidification method for Alum recovery from coagulation sludge were investigated in the test. The results show that when the recovery rate of Alum reaches its highest level, 84.5%, the reduction rate of sludge is 35.5%. It turns out that the capability of recovered coagulant to remove turbidity, UV(254) and COD are 96%, 46% and 53%, respectively. The results prove that the recovered coagulants could be used in CEPT and the efficiency of recovered coagulant to remove pollutants is similar to that of fresh coagulant. Although some substances will be enriched during recycle, they have little effect on the quality of treated wastewater. The experiments verify that it would be an advisable and cost-effective way to recover Alum from coagulation sludges in water treatment and chemical wastewater treatment, and it could be then recycled to CEPT as well as reduce sludge volume.     

Effect of OH-/Al3+ and Si/Al molar ratios on the coagulation performance and residual Al speciation during surface water treatment with poly-aluminum-silicate-chloride (PASiC)

Coagulation performance, mechanism of poly-aluminum-silicate-chloride (PASiC) and residual Al speciation in the effluent with respect to a specific surface water treatment in China were comprehensively investigated in this study. The impact of OH(-)/Al(3+) and Si/Al molar ratios on the coagulation performance, mechanism and residual Al speciation of PASiC in surface water treatment was discussed as a function of coagulant dosage. It was intended to provide an insight into the relationship between coagulation performance and residual Al. Experimental results revealed that when OH(-)/Al(3+) molar ratio = 2.00 and Si/Al molar ratio = 0.0500 in PASiC coagulant, PASiC exhibited beneficial coagulation property and relatively lower content of residual Al. Surface bridging and entrapment was more effective compared with charge neutralization during the specific surface water treatment. The majority of residual Al in the effluent existed in the form of insoluble suspended or particulate Al. Dissolved organically bound Al was almost the major speciation in dissolved Al and dissolved inorganically bound monomeric Al was the only component in dissolved monomeric Al. Al in PASiC remained abundant at lower dosages and residual Al concentration could be effectively reduced at the dosages of 12.0-15.0mg/L as Al.     

Advanced treatment of coking wastewater by coagulation and zero-valent iron processes

Advanced treatment of coking wastewater was investigated experimentally with coagulation and zero-valent iron (ZVI) processes. Particular attention was paid to the effect of dosage and pH on the removal of chemical oxygen demand (COD) in the two processes. The results showed that ZVI was more effective than coagulation for advanced treatment of coking wastewater. The jar tests revealed that maximal COD removal efficiency of 27.5-31.8% could be achieved under the optimal condition of coagulation, i.e. 400mg/L of Fe(2)(SO(4))3 as coagulant at pH 3.0-5.0. On the other hand, the COD removal efficiency could be up to 43.6% under the idealized condition of ZVI upon 10 g/L active carbon and 30 g/L iron being dosed at pH 4.0. The mechanisms for COD removal in ZVI were dominated by coagulation, precipitation and oxidation-reduction. ZVI would also enhance the biodegradability of effluent by increasing BOD5/COD from 0.07 to 0.53. Moreover, some ester compounds could be produced in the reaction. Although ZVI was found more efficient than coagulation in eliminating low molecular weight (<2000 Da) compounds in the wastewater, there were still a few residual contaminants which could hardly be eliminated by either of the process.     

Treatment of desizing wastewater by catalytic thermal treatment and coagulation

In the present study, the coagulation of the fresh and thermally treated desizing wastewater has been reported. The maximum COD reduction of fresh desizing wastewater using coagulation was observed with commercial alum at initial pH 4. This was followed by aluminum potassium sulfate (pH 4), FeCl(3) (pH 6), PAC (pH 6) and FeSO(4) (pH 4). The maximum COD reduction observed at a coagulant (commercial alum) dose of 5 kg/m(3) and pH 4 was 58% whereas the color reduction at these conditions was 85%. The results reveal that the application of coagulation on the catalytic thermal treated effluent is more effective in removing nearly 88% of COD and 96% of color at above mentioned conditions except at a coagulant dose of 1 kg/m(3). The amount of inorganic sludge generated gets drastically reduced (almost 25%) due to the reduced amount of coagulant. The COD and color of the final effluent were found to be 98.6 mg/l and 2.67 PCU, respectively, and the COD/BOD(3) ratio was 1.36. The settling rate of the slurry was found to be strongly influenced by treatment pH. The slurry obtained after treatment at pH 12 settled faster in comparison to slurry obtained at pH 4. The filterability of the treated effluent is also strongly dependent on pH. pH 12 was adjudged to be the best in giving highest filtration rate.     

Pretreatment of palm oil mill effluent (POME) using Moringa oleifera seeds as natural coagulant

Moringa oleifera seeds, an environmental friendly and natural coagulant are reported for the pretreatment of palm oil mill effluent (POME). In coagulation-flocculation process, the M. oleifera seeds after oil extraction (MOAE) are an effective coagulant with the removal of 95% suspended solids and 52.2% reduction in the chemical oxygen demand (COD). The combination of MOAE with flocculant (NALCO 7751), the suspended solids removal increased to 99.3% and COD reduction was 52.5%. The coagulation-flocculation process at the temperature of 30 degrees C resulted in better suspended solids removal and COD reduction compared to the temperature of 40, 55 and 70 degrees C. The MOAE combined with flocculant (NALCO 7751) reduced the sludge volume index (SVI) to 210mL/g with higher recovery of dry mass of sludge (87.25%) and water (50.3%).