Two culture approaches used to determine the co-composting stages by assess of the total microflora changes during sewage sludge and date palm waste co-composting

Abstract

Indigenous microflora community changes during six months of co-composting of activated sewage sludge and date palm waste was investigated using two different culture approaches. In order to evaluate the co-composting process evolution for mixture A and B, growth standard media (GSM) and Compost Time Extract Agar (CTEA) are used. Enumeration for indigenous flora abundance on GSM medium shows that the colony-forming unit (CFU) total number was 100 fold higher than on CTEA. The thermophilic phase is determined at 30 day for both mixtures A and B. Nevertheless this stage is limited only at 22 and 30 days, respectively for mixture A and B on CTEA medium, which indicate a similar temperature profile at versus time of co-composting. The results suggest that the GSM medium approach can be used for monitoring the microbial cultivable presence. However, CTEA act as a natural selective medium to enumerate the indigenous functional microflora. This technique was successful in assessing the process evolution and determination of a real succession thermophilic and maturation co-composting stages.