Improvement of organics removal by bio-ceramic filtration of raw water with addition of phosphorus

The purpose of this study was to investigate the effect of phosphorus addition on biological pretreatment of raw water. Experiments were conducted in pilot-scale bio-ceramic filters with raw water from a reservoir located in Beijing, China. The results demonstrated that phosphorus was the limiting nutrient for bacterial growth in the raw water investigated in this study. The measured values of bacterial regrowth potential (BRP) and biodegradable dissolved organic carbon (BDOC) of the raw water increased by 50-65% and 30-40% with addition of 50 microg of PO4(3-)-PL(-1), respectively. Addition of 25 microg of PO4(3-)-PL(-1) to the influent of bio-ceramic filter enhanced the percent removal of organics by 4.6, 5.7 and 15 percentage points in terms of COD(Mn), TOC and BDOC, respectively. Biomass in terms of phospholipid content increased by 13-22% and oxygen uptake rate (OUR) increased by 35-45%. The ratio of C:P for bacteria growth was 100:1.6 for the raw water used in this study. Since change of phosphorus concentrations can influence the performance of biological pretreatment and the biological stability of drinking water, this study is of substantial significance for waterworks in China. The role of phosphorus in biological processes of drinking water should deserve more attention.     

Effects Of Ozone-Hydrogen Peroxide Combination On The Formation Of Biodegradable Dissolved Organic Carbon

The effects of ozone and ozone/hydrogen peroxide on BDOC formation were studied with the “Ozotest” method, a laboratory technique that permits the assessment of oxidation efficiency. Oxidation treatments were performed on river water and sand filter effluent samples. Ozone consumption, reduction of UV absorbance, and BDOC formation were monitored during the experiments. The ratio of 0.35-0.45 mg H₂O₂ per mg O₃ used to degrade pesticides also was optimal for the oxidation of organic matter. BDOC formation versus ozone dose curves with ozone alone or ozone/peroxide system were similar. BDOC formation was optimum at an applied ozone dose of 0.5-1 mg O₃/mg C (contact time = 10 min). The ozone/peroxide system yielded lower BDOC values than ozone alone, a phenomenon related to differences in byproducts generated by the two oxidative systems. Moreover, reduction of the concentration of DOC was higher with ozone/hydrogen peroxide than with ozone alone. For both oxidant systems, BDOC formation occurred during the first minute of treatment.     

活性生物砂法测定可生物降解溶解性有机碳

以附着活性细菌的生物砂为接种物,通过静态培养的方式测定饮用水中可生物降解溶解性有机碳（BDOC）。结果表明,活性生物砂法测定BDOC的最优操作条件为：接种量为0．33g生物彬mL水样,20℃下的恒温培养时间为10d。与传统的悬浮培养法相比,其对BDOC的降解速率快、能力强,可大幅缩短培养时间,提高BDOC测定的实用性和时效性。活性生物砂法测定中BDOC的降解基本符合一级反应动力学方程,但反应速率常数随水样的不同而有所差别。     

饮用水中生物可降解溶解性有机碳的研究现状

综述了饮用水中生物可降解溶解性有机碳(BDOC)与生物稳定性的关系,以及BDOC的测定方法.并且分析了在给水管网中水温、自由余氯和细菌总数等水质指标对BDOC的影响.     

Comparison of methods for the measurement of biodegradable organic carbon and assimilable organic carbon in water

In the last few years different methods for determining assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC) in drinking water have been proposed. However, there is no agreement on the most suitable methods for the assessment of treatment processes. A comparison of six methods, one for AOC(P17) determination and five for BDOC determination, using water samples taken at different steps in a water-treatment process in Sant Joan Despí (Barcelona, Spain) is reported. Results show that the biodegradable matter values given by AOC measurements are substantially lower than those obtained using BDOC methods. The various BDOC methods do not differ significantly in their results.     

优化混凝控制水中可生物降解有机物

研究了优化混凝条件下对水中可生物降解有机物的去除效率，并和水厂实际运行效率进行了比较。结果表明：①最优混凝的pH＝6．5—7．0，②最优混凝剂量一般为30—40mg/L，②优化混凝明显提高了混凝工艺对有机物的去除效率，对TOC、AOC和BDOC的去除率分别比水厂实际运行效率提高了9％～21％、0～29％和7％～24％。     

Pilot study on combined process of catalytic ozonation and biological activated carbon for organic pollutants removal

A combined process of catalytic ozonation in the presence of a novel heterogeneous catalyst and biological activated carbon was investigated for the removal of priority control organic pollutants, the reduction of genotoxicity, and the improvement of biodegradable dissolved organic carbon (BDOC). Results confirm that the catalytic ozonation has higher effectiveness for the removal of refractory harmful organic pollutants, the reduction of genotoxicity and the increase of bio-degradability of organics than ozonation alone, which results in lower pollution load for subsequent biological activated carbon process, and then leads to less organic pollutants penetrating biological activated carbon. The novel catalytic ozonation with this combined process exhibits excellent performance to guarantee the safety of drinking water.     

Removal of biodegradable dissolved organic carbon in a water treatment plant

A new scheme of treatment has been developed in the water treatment plant of Ivry-sur-Seine near Paris. This treatment consists of a pretreatment of preozonization, contact coagulation, coagulation on a filter, slow sand filtration, ozonization and GAC filtration. We have tested the efficiency of this new line of treatment for the removal of BDOC and have attempted to correlate the results with the removal of organic matter (global parameters). Results show a very good efficiency of slow sand filtration and we think that this treatment step allows production of a biologically stable water.     

Ozone and biofiltration as an alternative to reverse osmosis for removing PPCPs and micropollutants from treated wastewater

This pilot-scale research project investigated and compared the removal of pharmaceuticals and personal care products (PPCPs) and other micropollutants from treated wastewater by ozone/biofiltration and reverse osmosis (RO). The reduction in UV₂₅₄ absorbance as a function of ozone dose correlated well with the reduction in nonbiodegradable dissolved organic carbon and simultaneous production of biodegradable dissolved organic carbon (BDOC). BDOC analyses demonstrated that ozone does not mineralize organics in treated wastewater and that biofiltration can remove the organic oxidation products of ozonation. Biofiltration is recommended for treatment of ozone contactor effluent to minimize the presence of unknown micropollutant oxidation products in the treated water. Ozone/biofiltration and RO were compared on the basis of micropollutant removal efficiency, energy consumption, and waste production. Ozone doses of 4-8 mg/L were nearly as effective as RO for removing micropollutants. When wider environmental impacts such as energy consumption, water recovery, and waste production are considered, ozone/biofiltration may be a more desirable process than RO for removing PPCPs and other trace organics from treated wastewater.     

生物可降解溶解性有机碳(BDOC)降解动力学研究

以东北某市饮用水为研究对象,采用悬浮培养测定法,讨论了生物可降解性有机碳（BDOC）测定中降解动力学特性,得出在28d测定中,BDOC的降解动力学满足一级反应,动力学方程为BDOC1=BDOCu（1—10^-0.07449t）,降解常数k=0.07449d^-1．试验研究表明：BDOC3约占BDOC28总量的40．22％,以测定BDOC3代替测定BDOC28是可行的．试验还证明了UV254与DOC存在一定的相关性,通过对实验数据的拟和,求解出了相关方程为DOC=15UV254＋245．