Chlorination sewage effluent

Williams, M.L., Palmer, C.G. and Gordon, A.K. (2003) Riverine macroinvertebrate responses to chlorine and chlorinated sewage effluents - Acute chlorine tolerances of Baetis harrisoni (Ephemeroptera) from two rivers in KwaZulu-Natal, South Africa, Water SA 29 (4), 483-488. 

As a result of several studies, the following conclusions regarding viruses in sewage warrant consideration (1) primary sewage treatment has little effect on enteric viruses (2) secondary treatment with trickling filters removes only about 40 percent of the enteroviruses (3) secondary treatment by activated sludge treatment effectively removes 90 percent to 98 percent of the viruses and (4) chlorination of treated sewage effluents may reduce, but may not eliminate, the number of viruses present. 

Hexachloroethane may also be released to air during combustion and incineration of chlorinated wastes, from hazardous waste sites, and in small amounts during chlorination of sewage effluent prior to discharge and chlorination of raw water during drinking water treatment (Gordon et al. 1991 Howard 1989). 

Other organic compounds that have been determined in sewage effluents include the following (see Table 15.13) hydrocarbons, alcohols, carboxylic acids, esters, chlorobenzenes, nitrosamines, ethylene diamine tetraacetic acid, nitriloacetic acid, organophosphorus compounds, linear alkyl benzene sulphonates, methyl mercaptan, polychlorobiphenyls and chlorinated insecticides. 

Other organic compounds that have been determined in sewage effluents by gas chromatography-mass spectrometry include the following (Table 16.7) nanylphenoxycarboxylic acids, chlorinated hydrocarbons, polychlorobiphenyls, organochlorine insecticides, hexachlorophene, pentachlorophenol, A -(phenylsulphonyl) sarcosine, dimethyl di, tri and tetrasulphides, Abrazine, Nirex, and volatile organic compounds. 

Two different analytical methods were used to determine residual chlorine in sewage effluents. Both methods were used on the same samples, but each sample came from various locations, with differing amounts of contact time with the effluent. The concentration of Cl in mg/L was determined by the two methods, and the following results were obtained ... 

Many of the organic contaminants which were found in Lippe river water were also present in the source samples (see Table 3). The sewage effluent sample and the Seseke river showed the best accordance with the compound spectrum of the Lippe river. However, also in the two tributaries from the rural upper reaches of the river, numerous specific contaminants like 9-methylacridine (No. 8), alkyl phosphates (Nos. 31, 32) and chlorinated alkyl phosphates (Nos. 34, 36) appeared. In the effluent of a pharmaceutical plant, only a few Lippe river contaminants like n-alkanes (No. 1), naphthalene (No. 3), TXIB (No. 21) and caffeine (No. 67) were detected (see Table 3). Therein, mainly structural relatives of androstanone like 3p-hydroxy-5p-androstan-17-one, 3a-hydroxy-5p-androstan-17-one and androstan-50-3,17-dione were present. These compounds are probably by-products of the synthesis of hormone preparations. Some polycyclic aromatic compounds, halogenated compounds and terpenoids were not detected in the source samples (see the underlined compounds in Table 3) and probably have another origin. Representative sampling of various input sources have to be carried out to prove the origin of these compounds. Hexachlorobutadiene (No. 38) and bis(chloropropyl)ethers (No. 44) appear exclusively at the lower reaches of the Lippe river (see Table 1), downstream the chemical plants in Marl. They are attributed to inputs of the chlorochemical industry (see section 3.1). Hence, this suggests their input by an industrial point source. 

For the chlorinated benzenes, a very similar distribution within the sediment core is observed as for some PAHs, e.g. benzo[a]pyrene. An elevated large-scale industrial activity related to these compounds can be deduced for the time between 1947 and 1955. We attribute the decrease in contamination towards the top layers to a reduction of emissions as a result of more efficient sewage treatment plants (Fig. 1A,B) as well as a modified array of products. The concentration profile of HCB (Fig. 6C) and all lower chlorinated benzenes (Tab. 2) suggests the dominance of industrial sources responsible for the contamination as contrasted to agricultural emission derived from pesticide usage. It should be noted that the contamination level of 1,4-dichlorobenzene was elevated in the time period between 1975 and 1980, comparable with concentration levels determined in Rhine river sediments 1982/83. The extensive use of 1,4-dichlorobenzene as an odorous ingredient of toilet cleaners contributed additionally to the contamination via sewage effluents (LWA, 1987/1989). 

Chlorinated secondary effluent arrives at the pumping station, which is adjacent to the sewage treatment plant in Riyadh, through an open channel which flows to the pump station inlet basins. The 4.63 MGD of effluent is then pumped 19 kilometers to the refinery by either of two full capacity pumps which take suction from the inlet basins. The effluent is pumped through a... 

There are an estimated 10000 to 11000 organo-chlorines in commercial production and many thousands more may be present, but are as yet unidentified, as by-products of the production. In addition, processes such as chlorination of sewage effluent to kill bacteria, result in active forms of chlorine which react with natural organic chemicals in the sewage to produce a myriad of organo-chlorines perhaps hundreds to thousands depending on the effluent and the chlorination conditions. Small amounts of organochlorines are also reported to result from various combustion processes, both natural fires and volcanic eruptions, and human-controlled processes such as incineration of wastes. 

Calcium hypochlorite is a dry chlorine donor produced by the introduction of chlorine in aqueous suspensions of calcium oxide at 20° C. The product is suitable for use in applications where the disinfecting and oxidizing power of chlorine are needed e.g. in the beverage and food industry, and in hospitals for hard surface cleaning, for water treatment including waste water and sewage effluent, in pulp and paper mills, in taimeries. 

A portion of the effluent is recirculated, ia order to smooth out flow, keep the food concentration constant, lower film thickness and control psychoda flies, and reseed the appHed sewage with acclimatized organisms. The psychoda, or filter fly is a very small iasect that breeds ia thick trickling-filter slimes. It does not bite, but can be a nuisance. Its radius of flight is small, but it can be carried great distances by the wiad. The fly can be controlled ia the development phase by occasional flooding of the filter or chlorination of the appHed sewage. 

Another approach consists of an in-situ acetylation and extraction of NPEOs and further analysis of the acetyl derivatives. The method has been applied to analyse effluent water and sewage sludges [102,103], sediments [104] and river waters [105]. Silylated derivatives [106] using BSA or BSTFA have also been used to determine NPEO (n < 6) in seawater [107] and wastewater [107,108], sediments [109] and sludges from wool scour effluents [110]. Halogenated derivatives of alkylphenols (AP) can also be formed as a result of chlorination practices in water treatment or wastewater if bromide is present. Brominated OPs and NPs (BrAPEOs) have been identified by GC-MS in sewage [111] and tap water [89], respectively. 

Planas C, Palacios O, Ventura F, Rivera J, Caixach J (2008) Analysis of nitrosamines in water by automated SPE and isotope dilution GC/HRMS - Occurrence in the different steps of a drinking water treatment plant, and in chlorinated samples from a reservoir and a sewage treatment plant effluent. Talanta 76 906-913... 

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