Reviewer response for version 1

Abstract

Flocculation has been widely used as one of the most effective methods for removal of suspended particles in water or wastewater treatment. Flocculants are conventionally used because of their high flocculating activity, low-cost production and availability. However, flocculants have been reported to have negative impacts on the environment and have caused some serious health problems including neurotoxicity and cancer-genic to humans. Consequently, bioflocculants appear to be an alternative to synthetic flocculants because bioflocculant are eco-friendly, biodegradable, non-toxic and able to function at a low dosage. In this study, the bioflocculant producing bacterium was isolated from Tendele coal mine and identified by 16S rRNA gene sequencing analysis. The isolated bacterium has about 99% estimated with Proteus Mirabilis and was named as Proteus mirabilis PJC12 with accession number MK 802115.1. Its culture conditions such as inoculum size, carbon and nitrogen sources, pH, temperature, shaking speed and time were optimised using the one-factor at a time assay. A 1% (v/v) inoculum size was selected as the optimum size for bioflocculant production by P.mirabilis PJC12 and was used subsequent experiments. Amongst all carbon and nitrogen sources that were tested, fructose and yeast extract were the most favourable respectively. The pH, temperature, shaking speed and time were tested and pH 6, 30 o C, 140 rpm and 7 hrs were taken as optimum levels respectively.