Faecal pollution

In contrast, in developing countries published information on this topic is scarce, though existing information indicates that rain levels above background values also increase the amoimts of indicators in fresh water bodies. Blum et al. [32] described in Nigeria a peak period of faecal pollution of water sources in the transition between the dry and the wet seasons. Gasana et al. [33] described boosts of faecal contaminants in water supplies in Rwanda after heavy rain episodes. 

Kasprzyk-Hordem B, Dinsdale RM, Guwy AJ (2009) Illicit dmgs and pharmaceuticals in the environment - forensic applications of environmental data. Part 2 Pharmaceuticals as chemical markers of faecal water contamination. Environ Pollut 157(6) 1778-1786... 

The use of 56-cholestane-31 -ol (coprostanol) as a molecular marker of faecal pollution of water has been suggested [23-26]. It has been shown that this saturated sterol satisfies the criteria for an indicator of faecal contamination of water [22, 27]. 

Leeming R, Ball A, Ashbolt N, Nichols P, Using faecal steroids from humans and animals to distinguish faecal pollution in receiving waters. Water Research 30 2893-2900, 1996. 

Soupir, M. L., Mostaghimi, S., Yagow, E. R., Hagedorn, C., and Vaughan, D. H. (2006). Transport of faecal bacteria from poultry litter and cattle manures applied to pastureland. Water Air Soil Pollut. 169, 125-136. 

Pathogenic viruses, bacteria, protozoa and helminths may be present in raw municipal wastewater at the levels indicated in Table 11.3 and will survive in the environment for long periods. Pathogenic bacteria will be present in wastewater at much lower levels than that of the coliform group of bacteria, which are much easier to identify and enumerate (as total coliforms/100 ml). Escherichia coli are the most widely adopted indicator of faecal pollution and they can also be isolated and identified fairly simply, with their numbers usually being given in the form of faecal coliforms (FC)/100 ml of wastewater. 

Once released in the environment by means of human faeces or animal dejection, enterococci are able to colonise different ecological niches because of then-resistance to adverse environmental conditions. Enterococci are widely spread in nature, in soil, food, on plant and vegetables and surface water. They are used as indicators of faecal pollution in environmental waters (Godfree et al. 1997). 

Man excretes about 9 g of chlorides per day in urine, which increases the original content of chlorides in sewage. If chlorides are of animal origin, they indicate faecal pollution. High concentrations of chlorides occur in some industrial wastewaters (salting-out of products with sodium chloride, neutralization of HCl-containing waters). 

The content of phosphates in groundwaters to be used for drinking water supplies is considered to be an indicator of faecal pollution if they are of organic origin. As phosphates are well retained in soil, their indicator value is significant. 

In 1 ml of drinking water for local supply the maximum permissible count of mesophile germs (at 37 C) is 100, that of psychrophile (at 20 C), 500. Indicators of faecal pollution must be negative in 50 ml. 

Faecal water pollution is characterized bacteriologically by the determination of coliform microbes. It is expressed either in counts of microbes per ml of water, or the minimum quantity of water in which the above specified microbes are stiU present. 

A variety of physiological groups of bacteria are of importance for water quaUty. They participate in various natural processes in water. In addition, other bacteria are introduced from the environment, indicating general and faecal pollution. They include conditionally pathogenic and pathogenic bacteria. 

Bacterial indicators of general pollution include saprophytic mesophilic, psychrophilic and anaerobic bacteria. Indicators of faecal pollution include coUform bacteria, enterococci and clostridia. 

Kanazawa, A. and Teshima, S., 1978. The occurrence of coprostanol, an indicator of faecal pollution, in sea water and sediments. Oceanol. Acta, 1 39—44. 

The most important tests for indicators, which give a microbiological feel for the produce, are the Total Aerobic Viable (plate) Counts (TVAC), and a test for the presence of coliforms as indicators of faecal pollution. Other tests for indicators may be necessary for certain products or under certain storage conditions, e.g. psychrophilic plate counts for items stored at low temperature, anaerobic plate counts for suspect tinned items, and tests for enterococci in cases of suspected food poisoning. In certain items of produce, large numbers of indicator organisms may also pose a threat to health in their own right. 

There may be some overlap between these groups. For example. Staphylococcus aureus may be just an indicator of generally unhygienic conditions, or it may produce staphylococcal enterotoxin causing very rapid symptoms (two hours) of gastro-enteritis. Similarly, Escherichia coli can cause an infection, be toxigenic, or just be an indicator of faecal pollution. 

Tests for coliforms or Enterobacteriaceae are useful for monitoring the effectiveness of mild heating (pasteurisation) and as an indicator of recontamination. The presence of coliforms does not indicate faecal pollution as there are a... 

E. coli is very rarely found in water when faecal pollution is absent, and testing for E. coli and coliforms is the most sensitive method of demonstrating faecal pollution. Confirmation of the presence of E. coli indicates faecal pollution and the possible presence of intestinal pathogens. High counts suggest recent or heavy pollution, whilst low counts suggest slight pollution or pollution at some time in the distant past. 

The absence of E. coli combined with the presence of coliforms is more difficult to interpret. Whilst faecal pollution is the most probable explanation of contamination by coliforms, there are also other sources of coliforms which are generally innocuous, e.g. decaying vegetation and other organic matter such as washers and grease used in pipe joints. 

Geldreich, E.E. and Kenner, B.A. (1969). Concepts of faecal Streptococci in stream pollution. /. Water Pollut. Control Fed. 41 336-352. 

Water pollutants can also include excessive amounts of heavy metals, radioactive isotopes, faecal coliform bacteria, phosphorus, nitrogen, sodium and other useful (even necessary) elements as well as certain pathogenic bacteria and viruses (Botkin and Keller, 1998). 

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