Abstract:

Objective To investigate the efficacies of three-squared septic tank and anti-fecal pollution treatment system in killing schistosome eggs and capacity to treat the domestic sewage. Methods Schistosome eggs obtained from the infected rabbits were respectively placed in the three-squared septic tank and anti-fecal pollution treatment system in the first tank, then were taken and hatched at day 5, 10, 15, 20, 25, 30 and 40, respectively for counting the miracidia. The wastewater was taken from the outlet of experimental reservoir A and B, respectively, and determined for the treatment effect and discharge value pertaining to chemical oxygen demand(COD), total phosphorus(TP) and total nitrogen(TN) by level B standard specified in “GB18918-2002 Discharge standard of pollutants for municipal wastewater treatment plants”. Results Inactivation of the eggs required 15 days for the "standard eggs" and "fecal residual eggs" in the reservoir A, and 15 days for "standard eggs" and 20 days for "fecal residual eggs”in reservoir B. By the GB18918-2002 discharge standard, the index of COD, TP and TN in the sewage obtained from the three-squared septic tank were seriously beyond the specific standard, whereas the index for the three factors in the anti-fecal pollution treatment system were up to the standard in three tests. Conclusion Although both treatment techniques can thoroughly kill the schistosome eggs, yet anti-fecal pollution treatment system can be biologically efficacious in removing COD, TP and TN in the domestic sewage, leading to its discharge meeting the standard of level B in GB18918- 2002.

Key words: Schistsomiasis, Harmless treatment system, Three-squared septic household tank, Hygienic evaluation