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Chemical and Biological Phenomena Observed with Sewage Sludges in Simulated Soil Trenches

Taylor, J. M., Epstein, E., Burge, W. D., Chaney, R. L., Menzies, J. D., Sikora, L. J.
Journal of environmental quality 1978 v.7 no.4 pp. 477
sewage sludge, soil amendments, Zea mays, corn, roots, root growth, anaerobic conditions, gas production (biological), carbon dioxide, methane, methane production, ammonium nitrogen, soil pollution, coliform bacteria, nitrate nitrogen, zinc, copper, bioaccumulation, leaves
Chemical and biological observations were made on sewage sludge in a simulated trenching system in the greenhouse. Limed and unlimed raw and digested sludges were placed in simulated trenches in soil profile boxes in which corn (L.) was sown. During the 160-day growth period, roots penetrated entrenched digested sludge and root growth proliferated throughout the sludge. Root penetration into the raw sludges was severely restricted. Gas analysis showed that anaerobic conditions prevailed for extensive periods during the 160 days in raw sludge. Methane and CO levels reached 45 and 25%, respectively. The levels of CH and CO were < 3 and 21%, respectively, in the digested sludge boxes. Nitrate nitrogen, adjacent to and beneath the sludge, was generally higher with digested than with raw sludge. Zinc and copper did not move from the sludge into the surrounding soil. The increase of these metals in corn leaves was relatively low, reaching only 131 /g Zn and 5.9 /g Cu as compared with 79 /g Zn and 3.8 /g Cu in the controls. Although low levels of fecal coliforms survived in the sludge, none were found in the soil surrounding the sludge. Total coliform numbers in the sludge after 160 days were negatively correlated with NH-N concentrations, suggesting that NH, generated on dissociation on NH, may be important in reduction of human pathogens.