Date of Award

1998

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Thomas Lawson

Abstract

Disposal of crawfish processing wastes poses a challenging problem to the rapidly expanding crawfish industry. Co-composting is examined as a waste management alternative to landfill disposal. Wood chips, rice hulls, bagasse, and bark were evaluated for use as bulking agents in composting crawfish processing residuals. Use of bagasse as a bulking agent led to the largest reduction in volatile solids, organic-C, particle size, and compost volume. Finished compost using bagasse contained the greatest concentration of N. Self-heating patterns and decomposition of crawfish residuals were satisfactory using all four bulking agents. The finished products of all compost mixtures were stable and possessed good structure. Leachate and runoff management from compost constitutes a challenging problem for compost facility designers and operators. The problem is extended where highly putrescent materials, such as fisheries processing residues, are composted. Nutrient losses through leaching and rainfall runoff were evaluated over a 50-day period in a pilot-scale windrow composting study. Crawfish processing residuals and rice hulls were mixed in a 1:1 ratio by weight and the mixture was windrowed on liners to capture leachate and runoff. Water for moistening the windrows was supplied by (1) leachate and runoff for one windrow; (2) tap water for the second; and (3) naturally-occurring rainfall events for the third. It can be beneficial to add leachate and runoff water to the pile during early stages of composting to provide adequate moisture and replenish some of the nutrients that could have been lost otherwise. Degradation of mass, microbial activity, and nutrient content was determined during composting of different mixtures of rice hulls and crawfish residuals. This experiment was also undertaken to assess the suitability of recycling compost product with additional crawfish residuals. Mixtures containing high percentage of crawfish residuals had the highest degradability, microbial activity, and nutrient content. The reuse of the recycled product induced higher degradation in the recycled product as well as complete degradation of the crawfish residuals.

ISBN

9780591904789

Pages

129

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