Management of human excreta.

Abstract

In China human excreta has been applied as an organic fertilizer to farmlands because of its high fertilizing efficiency and the substantial quantity available. Agricultural production at the time of liberation was based primarily on small scale farming by individual households. Each household had a private vat for storing its own excreta for use as fertilizer. Water sources were heavily contaminated by excreta leading to continuing transmission of parasitic and infectious enteric diseases. The prevalence of schistosomiasis in endemic areas was about 26% reaching a maximum of over 60% in 1 commune. The average rate of hookworm infection was 36.5% in 1956 and the mortality rate of infectious enteric diseases was 13.7/100000 in 1960. Thus proper management of excreta was a measure of critical importance in reducing disease and raising the populations health level. The 1st step taken in 1953 recommended that all excreta vats in schistosomiasis endemic areas be moved away from river banks to prevent the contamination of water sources. Additional developments in 1956 were the institution of small scale centralized management of excreta vats and the ban against washing of night commodes and related tools in rivers. At that time 83.6% of the 71888 private excreta vats in schistosomiasis endemic areas were brought under centralized management. To kill parasite ova and eliminate schistosomiasis initial efforts were directed toward the grouped excreta vats. A small shed was built over each group of vats and each vat was equipped with an airtight cover. This allowed the sealing of the vats to permit storage of the excreta under anaerobic conditions. In 1964 special tanks were developed to allow fermentation of the excrement and sedimentation of parasite eggs. These fermentation and settling tanks have been found to be a practical way of treating excreta and replaced the small scale groupings of vats and sealed storage treatment. During the 1964-1980 period 2545 fermentation settling tanks were constructed. Study results have demonstrated the effectiveness of the tanks. Recently biogas generators have been developed which provide for the production of biogas and allow fermentation and sedimentation. All measures taken in excreta management over the past 25 years have had a role in controlling and eliminating enteric parasitic and infectious diseases.