Predicting flocculant dosage in the drinking water treatment process using Elman neural network

Environmental Science and Pollution Research - Predicting the flocculant dosage in the drinking water treatment process is essential for public health. However, due to the complexity of water...     

蒙脱石絮凝剂对疏浚底泥的絮凝快速分离

为了快速对污染的河道湖泊进行清淤,使用酸改性的蒙脱石絮凝剂(MTSF)对底泥泥水进行了一级强化处理研究。结果表明:MTSF对底泥泥水具有很好的絮凝效果,当MTSF为0.3 g时,上清液的Zeta电位大约为0 mV,浑浊的泥水变为清澈透明,此时浊度、NH_4~+-N、 TP、 SS和COD的去除率分别为98.8%、 29.8%、99.6%、97.7%和56.9%;C-PAM助凝剂的少量投加,有助于絮凝过程,MTSF为0.3 g,C-PAM为8 mg·L~(-1)时,上清液的浊度和COD将会进一步降低,分别从9.0 NTU和51.6 mg·L~(-1)减少到4.7 NTU和15.0 mg·L~(-1);C-PAM助凝剂能够将絮体进一步结团,形成更大的絮体,促进絮体的快速沉降,同时还有助于对水相中污染物的进一步去除。两者的结合可以减少MTSF用量,达到更好的效果。     

多硫化钙与亚铁盐联用去除工业废水中的Cr(Ⅵ)

还原稳定化修复技术是当前重金属污染修复领域的主要技术,其中,重金属去除率和环境扰动是评价修复效果的重要指标.以不同pH重铬酸钾溶液模拟Cr(Ⅵ)污染水体,分别研究了多硫化钙、硫酸亚铁和二者联用对水体重金属Cr(Ⅵ)的还原稳定性,同时考察了环境因素对药剂联用的影响并探究各药剂对Cr(Ⅵ)的去除机理.结果表明:当多硫化钙与...     

臭氧-BAF组合工艺处理电镀RO浓水

电镀废水反渗透（RO）浓水具有盐度高、难降解有机物浓度高、含重金属等特点,是电镀废水处理工艺提标改造的难点。采用臭氧-曝气生物滤池（BAF）组合工艺,对电镀废水反渗透（RO）浓水中有机物进行处理,使出水COD浓度达到《电镀污染物排放标准》中标准。考察了废水初始pH、臭氧浓度和反应时间等因素对臭氧氧化效果的影响,以及水力停留时间（HRT）和气水比对BAF单元COD去除效果的影响。经优化后的系统运行工况为：臭氧氧化单元中废水初始pH值为10.0,臭氧浓度为31.96 mg·L-1,反应时间为40 min;BAF的HRT为3 h,气水比为5∶1。在最佳工况下,当进水COD为180~240 mg·L-1时,经组合工艺处理后COD去除率达78.6%,平均出水COD浓度为47 mg·L-1,达到了标准的要求。     

Reduction of greenhouse gases from anaerobic piggery wastewater treatment by bromochloromethane in Taiwan

This work establishes methods of reducing the amount of methane produced from the anaerobic treatment of piggery wastewater by either reducing the storage time before solid/liquid separation or inhibiting the activity of methanogens in anaerobic wastewater treatment system. Experimental results showed these two methods can be adopted effectively to reduce methane production resulting from anaerobic piggery wastewater treatment. First, the wastewater must be processed using solid/liquid separation immediately after washing pig houses. This process can reduce by 62% the biogas production and indirectly decrease the methane production from the anaerobic wastewater treatment reactor. Second, adding 10 mg L(-1) bromochloromethane (BCM) daily into the anaerobic wastewater treatment reactor can significantly reduce the amount of biogas and methane produced during the anaerobic fermentation process. Furthermore, biogas production can be completely inhibited after 4 days. Adding BCM (< or =10 mg L(-1)) to wastewater only slightly affected the efficiency of the anaerobic wastewater treatment process. Results in this study can provide the basis for further research on reduction of the amount of methane produced from anaerobic wastewater treatments.     

Biodegradation of nonylphenol in river sediment

We investigated the biodegradation of nonylphenol monoethoxylate (NP1EO) and nonylphenol (NP) by aerobic microbes in sediment samples collected at four sites along the Erren River in southern Taiwan. Aerobic degradation rate constants (k1) and half-lives (t1/2) for NP (2 microg g(-1)) ranged from 0.007 to 0.051 day(-1) and 13.6 to 99.0 days, respectively; for NP1EO (2 microg g(-1)) the ranges were 0.006 to 0.010 day(-1) and 69.3 to 115.5 days. Aerobic degradation rates for NP and NP1EO were enhanced by shaking and increased temperature, and delayed by the addition of Pb, Cd, Cu, Zn, phthalic acid esters (PAEs), and NaCl, as well as by reduced levels of ammonium, phosphate, and sulfate. Of the microorganism strains isolated from the sediment samples, we found that strain JC1 (identified as Pseudomonas sp.) expressed the best biodegrading ability. Also noted was the presence of 4'-amino-acetophenone, an intermediate product resulting from the aerobic degradation of NP by Pseudomonas sp.     

Effects of polydiallyldimethyl ammonium chloride coagulant on formation of chlorinated by products in drinking water.

The objectives of this research work was to evaluate the reduction of THM precursors by cationic p-DADMAC and determine the correlations between the chlorine demand and trihalomethane formation in the presence of electrolyte solutions and ambient light. The chlorine demand was found to be significantly reduced provided that the H2SO4 electrolyte was fed to the sample solutions. The amount of CHCl3 formation was also decreased when the Na2SO4 electrolyte was introduced in spite of the levels of light intensity. The p-DADMAC can not only effectively remove the turbidity but also reduce the formation of CHCl3. The optimum dosage of p-DADMAC for reducing the turbidity, TOC and CHCl3 in the humic acid and source water samples was determined and depended upon the nature of organics.     

Mass-size distributions of particulate sulfate, nitrate, and ammonium in a particulate matter nonattainment region in southern Taiwan

Concentrations and distributions of three major water-soluble ion species (sulfate, nitrate, and ammonium) contained in ambient particles were measured at three sampling sites in the Kao-ping ambient air quality basin, Taiwan. Ambient particulate matter (PM) samples were collected in a Micro-orifice Uniform Deposit Impactor from February to July 2003 and were analyzed for water-soluble ion species with an ion chromatograph. The PM1/ PM2.5 and PM1/PM10 concentration ratios at the emission source site were 0.73 and 0.53 and were higher than those (0.68 and 0.48) at the background site because there are more combustion sources (i.e., industrial boilers and traffic) around the emission source site. Mass-size distributions of PM NO3- were found in both the fine and coarse modes. SO4(2-)and NH4+ were found in the fine particle mode (PM2.5), with significant fractions of submicron particles (PM1). The source site had higher PM1/PM10(79, 42, and 90%) and PM1/PM2.5 concentration ratios (90, 58, and 93%) for the three major inorganic secondary aerosol components (SO4(2-), NO3-, and NH4+) than the receptor site (65, 27, and 65% for PM1/PM10, 69, 51, and 70% for PM1/PM2.5. Results obtained in this study indicate that the PM1 (submicron aerosol particles) fraction plays an important role in the ambient atmosphere at both emission source and receptor sites. Further studies regarding the origin and formation of ambient secondary aerosols are planned.     

Management and performance of Taiwan's waste recycling fund

Taiwan's resource recycling program was formally established in 1989, starting with the mandatory recycling of polyethylene terephthalate bottles. The number of mandatory regulated materials was extended to 8 categories with 27 items by 2002. Because of false data reporting, financial scandal, lack of transparency of the system, and the demand from parliament, the recycling policy has gradually changed from entirely privatized to being nationalized. Currently, the structure is built on six main bodies: fund management committee, consumers, industries responsible, recyclers, fee reviewing committee, and auditing agents. The industries that are responsible submit a fee, which is set by the fee reviewing committee, to the waste recycling fund (WRF), which is operated by the fund management committee. The auditing agents routinely check the responsible industries by documentation review as well as on-site counting to ensure that the fee is correctly submitted. The WRF provides initiatives to collect and dispose of the end-of-life products. The fund is split into a trust fund and a nonbusiness fund to deal with the collection, disposal, and treatment of the listed materials. The latter deals with the supporting works and ensures that the system runs effectively. The ratio of trust fund to nonbusiness fund is 80-20%. It is no doubt that the current practice achieves some improvements. Household waste has been reduced by 22%. And, most importantly, the benefit-to-cost ratio was as high as 1.24. However, similar to other state-owned systems, the resource recycling program has been criticized for false reporting from the responsible industries, a rigid system, and complicated procedures. To build a sustainable enterprise, the recycling program should be privatized as the recycling market and operating procedures are well established and fully mature.     

EDTA-assisted phytoextraction of lead from lead-contaminated soils by Echinochloa crusgalli var. frumentacea

The herbaceous plant Echinochloa crusgalli var. frumentacea is highly resistant to a wide range of heavy metal concentrations. In this study we tested the phytoextraction capacity of E. crusgalli var. frumentacea. Specifically, we compared the effect of EDTA on lead (Pb) accumulation in two groups of plants: those sown in lead contaminated soil and those transplanted to the contaminated soil as seedlings. The result of the time development of the Pb concentrations in the plants in the seedling and seed groups shows that for the seedling group, the effect of adding EDTA to the Pb-contaminated soil was even more pronounced in the shoots than the roots, which showed Pb concentrations 32-fold higher. Compared to the seedling group, the Pb concentrations in the roots of plants in the seed group were approximately 5 times higher in controls and 2 to 10 times higher in the presence of EDTA. Collectively, these results might be considered that EDTA elevates the bioavailability of Pb in soil and this native species is particularly suited to use in Pb phytoextraction.