UBC Theses and Dissertations
Two-stage anaerobic digestion of hog wastes Duncan, Adrian C.
The present trend towards concentrated land-use animal farming has given rise to a number of new animal waste disposal problems due to the very high strength of liquid wastes from such facilities. One treatment alternative applicable to these wastes is anaerobic digestion. A study was undertaken to determine the anaerobic digestion characteristics of waste from a high-density hog-raising facility. Earlier work had provided treatment efficiency data for a single-stage, laboratory-scale anaerobic reactor, as well as giving certain design criteria for anaerobic lagoons. The present study was intended to provide a measure of the increase in treatment efficiency obtained through use of a two-stage anaerobic reactor, again on a laboratory scale, and to give information regarding biodegradability of the settled sludge. The effect of variations in temperature and detention time was included in the study, as was an investigation of volatile acids, total organic carbon, and copper toxicity due to the use of brass fittings in test apparatus. Conclusions reached on the basis of this study were that the two-stage system gives a slightly higher loading capacity, due to improved settling capability, but the effluent from the second cell is still of higher strength than is often desirable for discharge to receiving waters. The settled solids were found to be degradable to a limited extent only, and thus most of them will require physical removal from a lagoon. No significant correlation was found between BOD, COD, and TOC and copper levels were found to reach significant levels in the reactors. This report was based on laboratory findings only. No correlation between laboratory-scale and field results was attempted in the study.
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