F ? r r stall a separate urine toilet (3 g"f ton n"1t f.;;;;*d ;; June 1977 RAIN page 11 COMPOST PRIVY UPDATE Owner-bu.ilt compost privies, costing less than $50 to build, are receiving more and more attenti6n as cosrs of conventional sewer or sepric tank systems become several thousand dollars per nouse. Compost privies generally rely on some combina_ uon oI rhree processes for preventing possible disease prob_ lems., 1) "Hot" composting that l.,r.iah. f,."i "i "..obi. .orn- ||:llg^ r: krlt parhogens and.evaporare urine, 2) Biological p_reoators-bugs in normal soil that ear the pathogens, ind 3) Ho.stile environments (cold, ulrraviolet, pHj etc.)*that starve' .:ll:l :Tflhogens. Retention rim.-iJ*irjir," sewase wnere noth_rngcan get to it for six months tJa year (asin a Llvus or )J-gal. drum privy) forms a combination of the lat_ ter rwo processes. In the absence of thorough health testingof many unirs, and because of .the .variability Jf operating praE_ tices, many people-use a redundant .o-birr"rL'n of tn?i. pro_ cesses to.ensure safety-often, performing a hot compost process on rhe wastes after they have been iiolated fo. i p.riJof time, and then restricting the use of tn. .ornp*t on food crops, play areas, etc. Detailed health studies of the first two processes have been la.de and they seem to operare satisfacrorily under most con_ ditions, but rreatment by hostile .nui.onrn.'nr, f r.nr.._p*_ hensive study. Claims hjve been -ra., *lin u"riou, a.gr"i, of substantiation, that exposure to the sun, cold and bacteria populations of soil through a winter is ad.quai. treatmenr in ::T.:..1t-j,,... Adding lime or wood ashes ,o -ou. the pH aoove IL) (a common privy management process),topr rn_ 1:T.?]: dl8esrion and producrion oT odors,'and may by itself provlcle- adequate treatment. And just setting the wastes aside in a sealed but vented 5S-gallon dium for an'extended period has.been proposed as the iimpler,,"f. *"y-,o'a."t *itti;;;;g. health problems. Thorough resting on ,n"1. f.oposals needs to be carried out .lnitial experience with both commercial and home_built units has revealed a number of common op.ruiion"t proli.rn, ;*:_T::,f .,-l1ral. be i1S overu se and urine overload.'M;;; ;i tne rnltlal demonstration Clivus installations were made in demonstration houses, schools o,,.r."..t lnriitut., "nd :il:l :l ::l"1ns 1a1r m.ore people than the single famity for ylrlch rhe{,were designed. Beer parties, campgro'und use, or nome rnsrallations where little kitchen *^rt. iu", added to compost and generate heat to evaporate moisture have caused waterlogging and anaerobic action (and smell) in large units and physical overflow in small oner The smail, etect"ricattyheated units have.had problems with arying ;r'baking the' wastes into brick-hard masses. Exhaust i"nl in bathrJoms with compost toilets have drawn the exhaust from the toilets into the room (solution, put rhe fan in the toif.i u.nt stack). The vent systems of many models draw from 2O to 4O cubic feet or atr per mlnute out of the house. During hcating seasons, that can be a significant hea^r.loss, The ma"in ;;;biems, however, conrinue to be l) urine, 2) flies, 3) smells anh +i nealttl sai.1y-' (pathogen destruction). .O Urine is a problem because almost every compost privy is based on aerobic composring, and the -oi'rrri. l" the urine Keeps alr trom the wastes. As a result, many privy builders try to separare as much of the urine ", poriibl. fiom the compost pile. Some, such as the Farallones urban house, in_ l s \. and pyrethium spray h"ave b.en us.J f;;?;;;;"j, Farallones' most recent composting priay, with seat and platform built for squatting or sitting. holding tank, which dilutes rhe urine auromatically for appli_ cation.to a garden. Others, such as Ken Kern, let the urine I'lt:r t^hl:ugl' the.compost and drain into an anaerobic (septic) ,,,Tf:-Srill others (Biopot desjgn) filter the urine through ' lrmestone, ashes and charcoal to neutralize it before Aiinlng into a soak pit. And some peopie p". or, ,...r. a Flies are alway.s a problem to deal with. They can wiggle lf l"r,g.h aery, small spaces, and it takes .*tr...iy carefu'i"craftr mansnlp and penodic monitoring (particularly on large units) to seal access points and keep rh'em sealed. The 55_gailon *l:ll: score high here again because of their so"lid, strong a.ncl slmple construction. Vents should be screened with mesh" fine enough to exclude fruit flies <-"ifJf"fro- laboratory s^upply houses, or use cloth.and windowscreen)- Even a peif:.;Y ::,11.., unit witl.get flies in tt a"rirj rr..'Spiders, beetles, O Odors are usually tied ro anaerobic activiry caused by urine wate.rlogging, and to the absence of adequate venting, and is usu.ally solved by resolving rhose problems (insulatin"g tank, 1dd.r.ng garden wasres, using windiurbine fans on top"of stack, dealing with urine separatiiy). Addition of cellulose_(planr) material is necessary in mosr situations.to provide carbbn-nitrogen balance for composting, to maintain a loose enough pile foi air to infiltrat. .".ily, uni toa.bsorb excess liquids. Moit_privy makers now warn againsr use ot sawdust, as ir is very. difficuit ro compost, requirJs a lot of oxygen for its own breikdown, ancl compacts into the pile . Straw, dirt, garden and kitchen clippings r..- ,o get highest scores from most people. Legalization of owner-built units still remains a hurdle in most areas. The Oregon legislature is now considering a bill to tegatne compost toilets. Drum privies can now be*legally constructed in Marin and Mendocino Counties in CalifJrnia. Though commelcially-made compost toilets "r" no* legal in a number of states, they almost invariably have not tested or approved owner-built units. A broad testing program ro resolve r^?T..""of the remaining que.stions of perfoniancJand reliabiliry of drtterent designs is needed to male broader legalization possible.
RkJQdWJsaXNoZXIy NTc4NTAz