Sources for isolation of extracellular polymeric substances (EPSs) producing bacterial strains which are capable of using wastewater sludge as solo substrate.

Isolation of extracellular polymeric substances (EPSs) producing bacterial strains capable of using sludge as low-cost growth substrate was carried out in this study. A total of 110 EPS-producing strains were isolated from different sources, which include sludge of beer and winery wastewater treatment plant (WWTP); young, 2-month-old and 10-year-old leachate. Thirty-seven isolated strains showed good growth in sludge medium with cell count varying from 106 to 1010 most probable number (MPN)/mL and total EPS concentration from 2737 to 6639 mg/L. Twenty-one strains produced EPS with high flocculation activity (FAmax varied from 72.0% to 80.2%). The highest FAmax (80.2%) was observed with EPS produced by strain BES 19, which was isolated from sludge of beer WWTP. Sludge of beer WWTP, young leachate and 10-year-old leachate were good sources for isolation of EPS-producing bacteria.

Adsorption and removal of arsenic from water by iron ore mining waste.

There is a global need to develop low-cost technologies to remove arsenic from water for individual household water supply. In this study, a purified and enriched waste material (treated magnetite waste, TMW) from the Trai Cau's iron ore mine in the Thai Nguyen Province in Vietnam was examined for its capacity to remove arsenic. The treatment system was packed with TMW that consisted of 75% of ferrous-ferric oxide (Fe(3)O(4)) and had a large surface area of 89.7 m(2)/g. The experiments were conducted at a filtration rate of 0.05 m/h to treat groundwater with an arsenic concentration of 380 microg/L and iron, manganese and phosphate concentrations of 2.07 mg/L, 0.093 mg/L and 1.6 mg/L respectively. The batch experimental results show that this new material was able to absorb up to 0.74 mg arsenic/g. The results also indicated that the treatment system removed more than 90% arsenic giving an effluent with an arsenic concentration of less than 30 microg/L while achieving a removal efficiency of about 80% for Mn(2 + ) and PO(4) (3-). This could be a promising and cost-effective new material for capturing arsenic as well as other metals from groundwater.