Method for monitoring the decomposition process in soil of organic wastewaters with high strength and low C/N ratio

Abstract

Abstract Squeezed fluid of pig manure and bonito processing wastewater, and their effluents from methane fermentation were studied in pot experiments in a model case of land application of organic wastewaters with high strength and low C/N ratio. Kanagawa alluvial soil (upland soil) and Kagoshima volcanic ash soil (upland soil) were used. The stabilization period of these four wastewaters in Kanagawa soil determined by gel chromatography was 14 days for an effluent from methane fermentation of bonito processing wastewater (EMB), 21 days for an effluent from methane fermentation of squeezed fluid of pig manure (EMP) and bonito processing wastewater (BPW), and 28 days for squeezed fluid of pig manure (SPM). Stabilization of all wastewaters occurred 1 week later in the Kanagawa soil than in the Kagoshima soil. In spite of apparent stabiliza- tion, inhibition of the growth of a 72 h seedling of Komatsuna (Brassica campestris L. var. rapiferafroug) was observed in EMB due to the accumula- tion of N02-N especially in the oligotrophic Kanagawa soil. In this case, mon- itoring of stabilization was achieved by both gel chromatography of a 1: 2.5 water extract of the wastes and soil mixtures and the use of a Merckoquant Nitrite Test strip for the detection and semiquantitative analysis of N02 ion.