Organic biofertilizer from brewery wastewater sludges via aerobic composting process

Abstract

The main purpose of this research was investigating the potential of aerobic composting process for Preparation of biofertilizer from brewery wastewater sludge (BWS) and spent brewery diatomaceous sludges (BSDS). In this study, BWS was mixed with BSDS sludges and, yielding three different mixtures to be composted. The composting process was assessed through measurements of temperature, moisture, pH, electrical conductivity, organic carbon, organic nitrogen, and total organic phosphorus contents. Moreover, the total concentration of heavy metals (Cr, Cu, Cd, Hg, and Pb) and the plant nutrients (Na, K, Mg, Ca, and Fe) were determined. Additionally, the degradation degree was evaluated through the detection and quantification of E. coli, Salmonella, and Fecal Coliform. It was found that the ratio of C/N was 9:1 and phosphorus fluctuated around 8.5%. Cr, Cu, Cd, Hg, and Pb were found 1.95 ± 0.045, 5.36 ± 0.03, 0.475 ± 0.004, 0.165 ± 0.004 and 0.273 ± 0.005 mg/kg respectively. Plant Nutrients Na, K, Mg, Ca and Fe were found at a concentration level of 100.16 g/kg, 122.95, 869.92, 4084.08 and 26.86 mg/kg respectively. Generally, aerobic compost of BWS and BSDS yielded acceptable quality of biofertilizer in line with EPA standard value limits. The higher pathogen (E. coli and Fecal Coliform) contents of raw sludges are stabilized in composting to the required standards and found far below upper EPA standard limits for unrestricted agricultural application.