The Use of Microorganisms for the Biodegradation of Sewage Sludge and the Production of Biocompost for Sustainable Agriculture

Abstract

Recycling by composting presents a sustainable and a cost-effective approach to reduce the high quantity of sewage sludge. In addition, the relationship between compost stability and functional microflora is reflected in the evolution of several parameters as C/N and NH4+/NO3- ratios. However, the microorganisms that populate the substrates during composting reflect the evolution and the performance of structural stability of amended soils, the water retention capacity, and the biodegradation-humification process in compost and soil. Therefore, monitoring humic substance variation during composting is one of the methods used to estimate microorganism activity. In this study, two different mixtures were prepared. The physicochemical indices of maturity changed during composting to reach C/N around 10 and H-4(+)/NO3- < 1. These two physicochemical indices of maturity presented a linear correlation with mesophilic actinobacteria with R-2 = 0.3 and 0.29 for C/N and R-2 = 0.29 and 0.41 for H-4(+)/NO3-, respectively, for mixtures A and B. However, for thermophilic actinobacteria, R-2 = 0.78 and 0.25 for C/N, and R-2 = 0.73 and 0.37 for H-4(+)/NO3-, respectively, for mixtures A and B. The progress of physicochemical and microbial parameters is justified by the germination of turnip seeds, which exceed 100% by using final composting products. These findings clearly demonstrate that exploitation of treated sewage sludge as a soil amendment could regulate the carbon, nitrogen, phosphorus, and organic matter requirements for a sustainable agriculture in Morocco where, for example, more than 6.25 million tons of organic matter is needed. PU - SPRINGER INTERNATIONAL PUBLISHING AG PA - GEWERBESTRASSE 11, CHAM, CH-6330, SWITZERLAND