Using Ruditapes philippinarum conglutination mud to produce bioflocculant and its applications in wastewater treatment

A novel bioflocculant-producing bacterium, ZHT4-13, was isolated from Ruditapes philippinarum conglutination mud. By biomicroscope morphological observation, 16S rDNA sequence identification and physiological and biochemical characteristics, strain ZHT4-13 was identified as Rothia sp. The bioflocculant MBF4-13 produced by strain ZHT4-13 had a flocculating efficiency of 86.22% for 5 g L−1 Kaolin clay suspension when the initial pH was 9 and the temperature was 20 °C. It had flocculating effect in a wide range, pH 1-13 and temperature 4-100 °C. Analysis of MBF4-13 by UV-Vis spectrophotometer, Fourier-transform infrared spectrophotometer (FT-IR) and 1H nuclear magnetic resonance (NMR) indicated that the main component of MBF4-13 is polysaccharide. The culture conditions to produce strain ZHT4-13 were optimized with orthogonal design of experiments. MBF4-13 had high efficiency in decolorizing dye solutions, had some abilities to remove heavy metal ions (Cr2O72−, Ni2+) and improve performance of activated sludge.