The effectiveness of sewage treatment processes to remove faecal pathogens and antibiotic residues

Pathogens and antibiotics enter the aquatic environment via sewage effluents and may pose a health risk to wild life and humans. The aim of this study was to determine the levels of faecal bacteria, and selected antibiotic residues in raw wastewater and treated sewage effluents from three different sewage treatment plants in the Western Cape, South Africa. Sewage treatment plant 1 and 2 use older technologies, while sewage treatment plant 3 has been upgraded and membrane technologies were incorporated in the treatment processes. Coliforms and Escherichia coli (E. coli) were used as bioindicators for faecal bacteria. A chromogenic test was used to screen for coliforms and E. coli. Fluoroquinolones and sulfamethoxazole are commonly used antibiotics and were selected to monitor the efficiency of sewage treatment processes for antibiotic removal. Enzyme Linked Immunosorbent Assays (ELISAs) were used to quantitate antibiotic residues in raw and treated sewage. Raw intake water at all treatment plants contained total coliforms and E. coli. High removal of E. coli by treatment processes was evident for treatment plant 2 and 3 only. Fluoroquinolones and sulfamethoxazole were detected in raw wastewater from all sewage treatment plants. Treatment processes at plant 1 did not reduce the fluoroquinolone concentration in treated sewage effluents. Treatment processes at plant 2 and 3 reduced the fluoroquinolone concentration by 21% and 31%, respectively. Treatment processes at plant 1 did not reduce the sulfamethoxazole concentration in treated sewage effluents. Treatment processes at plant 2 and 3 reduced sulfamethoxazole by 34% and 56%, respectively. This study showed that bacteria and antibiotic residues are still discharged into the environment. Further research needs to be undertaken to improve sewage treatment technologies, thereby producing a better quality treated sewage effluent

By-Side Impurities in Chloronaphthalene Mixtures of the Halowax Series: All 209 Chlorobiphenyls

202 congeners of chlorobiphenyl (CB) with 109 single-resolved compounds and 93 co-eluting, which represented from mono- to deca-CB were quantified as by-side impurities in all seven and of various type the technical chloronaphthalene (CN) formulations of the Halowax series. IUPAC No. 104, 145, 159, 169, 184, 186, and 188 were undetected (<0.05-<0.7ng/g). The total CBs content of the Halowax formulations ranged between 220 and 640,000ng/g, and lower chlorinated Halowaxes 1031 (27% Cl) and 1000 (35% Cl) were two to three orders of magnitude more contaminated with CBs than higher chlorinated Halowax 1001, 1099, 1013, 1014, and 1051 (49-70% Cl). The profile of CB homologue groups of the Halowaxes changed and followed somehow a degree of chlorination of the parent CN mixture. For Halowax 1031 and 1000, a decreasing trend in proportion from mono- to deca-CB was evident, while for Halowax 1001, 1099, 1013, 1014, and 1051 the relative proportions between the CB homologue groups varied somehow. Evidently content of lower chlorinated mono- and di-CBs highly decreased and steadily increased tri- to octa-CBs and they become dominating homologues in Halowax formulations in parallel with an increase of the content of higher molecular weight CN constituents, respectively. Among planar non- and mono-ortho CBs, total concentrations in Halowax formulations were detected in the range of 2.0-2600ng/g, and only 3,3',4,4',5,5'-HxCB (no. 169) was undetected (<0.05ng/g). Detection of by-side CBs in technical Halowaxes demonstrate clearly that those formulations apart from a massive introduction of dioxin-like CNs become in the past also an early source of environmental pollution with CBs, which proceeded for around 20-30 years use of original CB formulations.No Full Tex