Page 4 RAIN October 1978 _ [ ~r?IOr\ pt.O~~., ] rTIIU'-C>blOI (~,w,r~ PIU>PUC.."TS ) >--====..i.l.:====!l--=====-===---< ~lot\ c:::::::l==::;:=::s::ai--==-..... ~ =~anon ,fi,rhltttr......... ~=====--"-~.i~ ........ .wa dM,hU.f1on A.-,~,"''·~=~ Compost Fertilizer and Biogas Production from Human and Farm Wastes in the People's Republic of China, .ed. by Michael E. McGarry and Jill Stai,nforth, 94 pp., 1978, $5:oo printed, $1.00 microfiche from: International Development Research Centre Postal Address: Box 8500 Ottawa, CANADA KlG 3H9 This is the first thorough description of the long rumored proliferation of biogas plants in the People's Republic of China (PRC). The book is·a well edited version of papers " ... franslated from the Chinese and ... published in response to an increasing number of questions on Chinese practices and experiences in biogas production, excreta use a,nd,compos'ting." The PRC biogas plants are significantly different from the Gobar/Indian type biogas plants. The use of a fixed cover, concrete tank and rectilinear shape with no piping distinguish the PRC design. ' This unique plug flow design uses no restrictive plumbing like those of the Gobar type. Instead a generous channel opening for both the "intake chamber" and the "outlet chamber" allow an easily accessible and clog-free passage for the mixture of pig manure, crop residues and human fecal material. A one meter (35 cu. ft. or about 250 gallons) digester is generally sufficient to provide cooking gas for a family of five. The digesters are beiow·groun'd and require no heating. Operating temperature varies from 10° to 24° C. (50° to 75° F.) with .correspondingly higher gas production in the su.mmer when excess gas is used for cooking the animal feed. For hygienic purposes the digesters have proven significant in their reduction of parasite eggs, schistosome flukes, and hookworms. Liquid excreta is constantly removed for crop fertilizer since the digester is fed frequently with slug loads to mainta,in continuous treatment and gas production. The digeste!s are emptied and the accumulated -sludge is removed by hand once a year. The PRC digesters are the simplest and most appropriate small-scale systems I have seen. These could be significant in altering future toifet and septic practices both in,developing , and developed countries which are seeking simple but effective waste treatment. These are dearly unique and exceptional. We owe thanks to Dr. McGarry for his reporting of this excellent work. -KS the gasworl<s by Ken Smith . We have been twisting Ken Smith's arm for a bioconversion update, and these book reviews are the first squeezings. As his time and our space allow, Ken will also answer reader question-s on the growth, conversion, utilization and end-uses of energy from biological process.es. Ken is presently manager of the California Office of Appropriate Technology design team, having co-founded Ecotope Group, Inc., ofSeattle, wEich built a 1 oo;ooo gallon dairy methane plant under his direction. Ifyou've questions on his specialty, anaerobic digestion (methane gas production from organic decomposition in the absence of oxygen), or on alcohol pr,oduction or biomass farming, write him directly at OAT, 1530-lOth St., Sacramento, CA 95814.
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