Health effects associated with wastewater treatment, disposal, and reuse

Abstract

and transfer of fecal indicator organisms (coliforms, enterococci, sulphite-reducing clostridia, and coliphages) downstream of a wastewater treatment plant were investigated at Lake Kallavesi, Finland (R?jala and Heinonen-Tanski, 1998). The observation of indicator organisms up to 18 km from the discharge point and good survival in the summer suggested that direct use of lake water could constitute a health risk. The effect of combined sewer overflows (CSOs) on the occur rence of Giardia and Cryptosporidium was investigated (Gibson et al., 1998). The results suggested that CSOs significantly contribute to the load of Giardia and Cryptosporidium in ambient waters and source waters for drinking and recreational uses. An outbreak of waterborne giardiasis in Temagami, Ontario, in 1994 was assessed (Wallis et al., 1998). The outbreak was traced to leakage from the municipal wastewater system into the lake and exacerbated by spring snow-melt runoff. The influence of rainwater on the con centration of helminth eggs in wastewater was investigated (Capizzi and Schwartzbrod, 1998). Concentrations of parasite eggs vary according to water flow rates and sedimentation; heavy rain following rainless days yielded higher concentrations in raw wastewater at the treatment plant, whereas continuous moderate rain resulted in low variation of parasite eggs. The prevalence of respiratory symptoms, skin disorders, status of spirometric lung functions, and amino acid profiles among wastewater workers were reported (Bener et al., 1998). Wastewa ter workers had a higher prevalence of respiratory symptoms than controls, significant for chronic cough (p < 0.02), chronic phlegm (p < 0.03), chronic bronchitis (p < 0.02), asthma (p < 0.02), dyspneoa (p < 0.001), and nasal catarrh (p < 0.001) and acute symptoms of pruritus (p < 0.003), tinea (p < 0.004), dermatitis (p < 0.001), and nose irritation (p < 0.005). Spirometry tests scored lower in wastewater workers, and most of the plasma amino acids concentrations were elevated among wastewater workers. An investigation examining whether inadequate septic system construction may cause contamination of wells with coliform bacteria or nitrates was reported (Tuthill et al., 1998). The authors found that coliform bacteria and nitrate contamination were neg atively correlated with lot size, and coliform bacteria levels were negatively correlated with casing length, which suggested that septic systems may be a source of coliform bacteria and nitrate contamination in wells. CONTAMINATION OF WATER SUPPLIES