Environmental Management of Biosolids and Water Treatment Residuals
Abstract:As landfill space becomes less available, many municipalities will have to look towards alternative methods of waste disposal. Wastewater biosolids have been extensively studied and proven as a recyclable material. Water treatment plant residuals (WTR), on the other hand, have been but briefly studied. The Colorado Department of Public Health and Environment has established guidelines regarding land co-application of WTR and biosolids since the WTR is postulated to greatly reduce plant P availability and possibly provide an additional source of trace metals to soil. If co-application ratios can be established so as to not tie up P and limit its plant uptake, co-application will be an environmentally safe method of recycling. In a laboratory study, we investigated the biosolids-borne P adsorption capacity of an alum-containing WTR from two Colorado municipalities. Our adsorption study indicated that co-mixing of both municipalities' WTR and biosolids at ratios of 8:1 will adsorb most soluble biosolids P. Beyond this ratio the WTR could adsorb all biosolids available P and possibly some soil-borne P. In a greenhouse study we co-applied various ratios of WTR and biosolids to soil growing either blue grama (Bouteloua gracilis H.B.K. Lag) or western wheatgrass (Pascopyrum smithii (Rydb.) A. Love). A positive linear relationship was evident between increasing WTR rate and blue grama yield, and a negative linear relationship between increasing WTR rate and shoot phosphorus and aluminum concentration. We observed a negative quadratic relationship with increasing WTR rate and western wheatgrass shoot aluminum concentration. Some investigators have observed plant P deficiency symptoms associated with WTR application; however, we did not.
Document Type: Research Article
Publication date: 2001-01-01
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