Raking through sludge exposes a stink

Water and energy recovery: The future of wastewater in China

China is increasing its use of non-conventional water sources - seawater desalination, surface water transfer and wastewater reuse - to meet demand. Getting and treating water from these sources generally requires more energy than is needed for local freshwater sources. This increases the cost and greenhouse gas emissions associated with water supply. It also leads us to the question: are alternative water sources necessary and, if so, which source should be preferred? Here we argue that reclaiming and reusing wastewater is often the least energy-intensive alternative source for water-scarce areas of China, particularly when energy present in wastewater is recovered during the process.

Sewage sludge does not induce genotoxicity and carcinogenesis

Through a series of experiments, the genotoxic/mutagenic and carcinogenic potential of sewage sludge was assessed. Male Wistar rats were randomly assigned to four groups: Group 1 - negative control; Group 2 - liver carcinogenesis initiated by diethylnitrosamine (DEN; 200 mg/kg i.p.); Group 3 and G4-liver carcinogenesis initiated by DEN and fed 10,000 ppm or 50,000 ppm of sewage sludge. The animals were submitted to a 70% partial hepatectomy at the 3(rd) week. Livers were processed for routine histological analysis and immunohistochemistry, in order to detect glutathione S-transferase positive altered hepatocyte foci (GST-P(+) AHF). Peripheral blood samples for the comet assay were obtained from the periorbital plexus immediately prior to sacrificing. Polychromatic erythrocytes (PCEs) were analyzed in femoral bone-marrow smears, and the frequencies of those micronucleated (MNPCEs) registered. There was no sewage-sludge-induced increase in frequency of either DNA damage in peripheral blood leucocytes, or MNPCEs in the femoral bone marrow. Also, there was no increase in the levels of DNA damage, in the frequency of MNPCEs, and in the development of GST-P AHF when compared with the respective control group.