The Hydrozon-Kompakt Process-A New Method for Treatment and Disinfection of Swimming Pool and Bathing Water

The Hydrozon (R) Kompakt process (ozonation – sand filtration – bromination) relies on bromine (hypobromous acid/hypobromite ion) as the residual disinfectant in swimming pool and bathing water. As it performs its disinfection work, bromide ion is formed. Pool exit water is ozonized, not only to oxidize bather-added contaminants, but also to oxidize bromide ion back to hypobromous acid/hypobromite ions. Consequently, bromine is recycled in the pool water. However, the original process forms brominated hydrocarbons (brominated trihalomethanes), particularly bromoform, in excess of current German drinking water standards for total THMs (25 ug/L).     

Ozonation at Belle Glade,Florida : A Case History

In October 1984, the city of Belle Glade, FL installed a two-stage ozonation process for the treatment of lake water high in organics (av TOC 30 mg/L; up to 75 mg/L), high in color (av 100 color units; up to 500), and high in THM concentrations, at times nearly 1,000 μ/L. The new treatment process applied 3 mg/L of ozone to the raw water ahead of the flash mix basin, lime softening, alum and polymer coagulation, clarification, recarbonation, and addition of 3 mg/L ozone prior to filtration. Post-chlorination then produced distribution system THM concentrations averaging 124 μg/L. Distribution of THMs shifted from 85% chloroform by the original process to 40% after adoption of ozonation, the balance comprising brominated species (but not bromoform).

In 1987, the treatment process was modified by adding chlorine and ammonia at the outlets of the pre- and intermediate-stages of ozonation and abandoning free chlorination. This has further reduced the distribution system THM levels to 20-30 μg/L. Filtered water turbidity and color have been improved. The use of chloramines after ozonation controls the nuisance aquatic growths in the clarifiers and recarbonation basins (caused by ozonation alone), and produces a combined chlorine residual which can be maintained throughout the distribution system. Periodic use of free chlorine in the distribution system is required to prevent elevated heterotrophic plate counts and the formation of excessive concentrations of nitrite ion due to biological regrowth and nitrification.     

抗氧剂1520对溴化丁基橡胶热降解行为的影响

采用溶液法制备溴化丁基橡胶(BIIR),添加液体抗氧剂1520。为考察抗氧剂1520对BIIR热降解行为的影响,用热重分析仪在不同的升温速率下对橡胶进行热分解测定,采用Kissinger法和Flynn-Wall-Ozawa法计算非等温热分解反应的表观活化能,并用Coats-Redfern方程推断抗氧剂1520加入前后BIIR的热分解机理函数。结果表明,通过Kissinger法和Flynn-Wall-Ozawa法得到的结果一致,抗氧剂1520的加入明显提高了BIIR的热降解反应表观活化能。用Coats-Redfern方程推断出抗氧剂1520的加入使得BIIR的热分解反应机理由相界面反应机理转变为更复杂的三级化学反应机理。     

Brominated vegetable oil in soft drinks – an underrated source of human organobromine intake

In North America brominated vegetable oil (BVO) is frequently used as a clouding agent for soft drinks. BVO containing soft drinks have a market share of about 15% in the USA. In our study we analysed several soft drinks from North America for BVO and calculated exposures from our results and consumption data. Based on a mean content of 8 ppm in BVO-containing soft drinks, the average daily human intake of BVO exceeds the intake of other organobromine compounds, e.g., polybrominated diphenyl ethers (PBDEs), by >4000 times for adults and >1000 times for children. By comparing the patterns of the brominated fatty acids (BFA) in the soft drinks, we were able to distinguish three BVO products used by three soft drink manufacturers. The analysis also revealed that the predominant BFAs in BVO are the Br₂-18:0 (bromination product of oleic acid) and Br₄-18:0 (bromination product of linoleic acid).     

The removal of algal biomass and extracellular products from water

Abstract

The removal of algal biomass and algal extracellular products (ECPs) from eutrophic water is studied using various physical chemical methods including coagulation/precipitation, powdered activated carbon (PAC) adsorption and combination of coagulation/ precipitation and activated carbon adsorption. The removal efficiencies of algae and TOC are 96% and 81%, respectively, by coagulation/ precipitation method. Moreover, dissolved organic carbon (DOC) is divided into four groups based on molecular weight distribution. It is found that coagulation/ precipitation process has good DOC removal efficiency for high molecular weight groups whereas PAC adsorption is particularly effective of the removal of DOC of low molecular weight. It is also discovered that the removal efficiency is synergistic by coagulation/ precipitation followed by PAC adsorption. The formations of THMFP/ DOC and AOXFP/DOC are higher with high molecular weight groups than those with low molecular weight groups.     

Continuous flow method for determination of total trihalomethanes in drinking water with membrane-separation

A double-tube separation system with an inner tube of microporous poly(tetrafluoroethylene) (PTFE) and an outer tube of PTFE, is proposed for the continuous determination of TTHMs (total trihalomethanes) in drinking water. The TTHMs in the sample after mixing sodium sulfite solution, are separated with the double-tube system at 50°C and are mixed with alkaline nicotinamide solution, and then heated to 98°C. After cooling in an ice bath, the reaction product is fed to a fluorometer and the fluorescence intensity excited at 372 nm is measured at 467 nm. There was no interference from unknown species existing in drinking water and river water by using the membrane separation system. A response was obtained within 8 min. The detection limit (S/N = 3) was 0.8 μg/1. The present method was applied to the determination of the TTHMs in drinking water.     

Determination of several common disinfection by-products in frozen foods

Disinfected water and/or disinfectants are commonly used by the freezing industry in such processes as sanitising, washing, blanching, cooling and transporting the final product. For this reason, disinfection by-products (DBPs) can be expected in frozen foods. This study focused on the presence of DBPs in a wide variety of frozen vegetables, meats and fish. For this purpose, the 14 halogenated DBPs more prevalent in disinfected water were selected (four trihalomethanes, seven haloacetic acids, two haloacetonitriles and trichloronitromethane). Up to seven DBPs were found in vegetables, whereas only four DBPs were present in meats and fish, and at lower concentrations, since their contact with disinfected water is lower than in frozen vegetables. It is important to emphasise that trichloronitromethane (the most abundant nitrogenous DBP in disinfected water) was found for the first time in foods. Finally, it was concluded that the freezing process can keep the compounds stable longer than other preservation processes (viz. sanitising, canning) and, therefore, frozen foods present higher DBP concentrations than other food categories (minimally processed vegetables, or canned vegetables and meats).     

Continuous and efficient removal of THMs from river water using MF membrane combined with high dose of PAC

A combination of microfiltration (MF) membrane with a high concentration (40 g/L of the reactor) of powdered activated carbon (PAC) efficiently and continuously removed trihalomethanes (THMs) and total organic carbon (TOC) from river water for a period of two months. Without PAC, the membrane reactor was able to remove less than 18% of THMs and less than 5% of TOC; with PAC, 65 to 95% of THMs and TOC were removed. Even though the THMs concentration in the influent was steadily increasing (reaching 50 μg/L), THMs concentration in the effluents from the reactors with PAC were consistently below 15 μg/L. While the MF membranes alone could not remove organics, PAC and microbial activity in the biofilm deposited on the PAC particles assured long term and continuous removal of THMs. No additional PAC was added into or removed from the reactors during the filtration period. Operational parameters such as the backwashing of the membrane, interval of the filtration cycle and biological pretreatment of the river water had a small effect on the extent of THMs removal, but they increased the filtration time prior to membrane cleaning and improved the overall performance of the reactors.     

溴代三嗪阻燃剂对LGF/PA6复合材料阻燃机理及降解行为的影响

利用溴代三嗪(BrN)协同三氧化二锑(Sb2O3)制备N-Br-Sb阻燃长玻纤增强尼龙6复合材料(BrN/LGF/PA6),通过极限氧指数(LOI)、垂直燃烧(UL94)、热重分析法(TGA)、锥形量热分析(CONE)、红外光谱分析(FTIR)、扫描电镜(SEM)等方法研究了BrN协同Sb2O3对长玻纤增强尼龙6复合材料阻燃性能影响.结果表明,在BrN与Sb2O3的协效阻燃体系添加量为16％时,可使BrN/LGF/PA6复合材料的阻燃等级达到FV-0级,LOI为26.9％.锥形量热与热失重分析均表明,BrN协同Sb2O3能提高BrN/LGF/PA6复合材料的高温下热稳定性,促进PA6分解成炭,从而起到良好的阻燃作用.红外光谱、扫描电镜和锥形量热分析表明,LGF/PA6与BrN/LGF/PA6复合材料热处理后的炭层结构不完全相同,说明了BrN协同Sb2O3不仅在气相发挥阻燃作用,在固相也同样发挥阻燃作用.     

二级处理出水中DOM在粉煤灰改性SAT系统中的去除

为进一步改善土壤含水层处理(SAT)系统对城市污水处理厂二级处理出水中溶解性有机物(DOM)的去除效果,在传统SAT系统中以不同的混合比例及填充方式加入粉煤灰对其进行改性,并通过紫外254^nm处吸光度(UV²⁵⁴)、溶解性有机碳(DOC)、比紫外吸收值(SUVA)及三维荧光光谱(EEM)技术对二级处理出水中三卤甲烷(THMs)前体物在粉煤灰改性SAT系统中的去除情况进行探讨．粉煤灰改性SAT系统对二级处理出水中的UV254、DOC、SUVA及三卤甲烷生成势(THMFP)的去除效果优于传统SAT系统．粉煤灰添加量的增加能大幅度提高SAT的处理效果,但会影响土壤中微生物的活性,故有效结合粉煤灰的吸附性与土壤层的生物降解作用可提高SAT的处理效果．量化的荧光强度数据表明,粉煤灰改性SAT系统可有效去除二级处理出水中以络氨酸类芳香性蛋白质、腐殖酸及富里酸类物质为主的THMs前体物．