Possible denitrification technology for small settlement water supplies

A biological denitrification technology has been developed and tested. In the laboratory, the denitrifying bacteriumHyphomicrobium X was immobilised on polyurethane and polyvinylacetate foams, glass beads, glass wool, coarse river sand and also entrapped in alginate beads. In all cases the bacteria retained their capacity to actively denitrify with methanol as the carbon source. The establishment times and longevity of the bacteria on polyurethane and sand columns was studied, as was the effect of methanol/nitrate ratios on the denitrification process in flow-through experiments. Conditions were achieved where both nitrate and methanol were removed stoichiometrically. Complete removal of nitrate could be achieved in the temperature range 4 to 48 °C. Flow-through and batch procedures were investigated and a prototype batch system was developed which was capable of treating 200 litres of nitrate-containing water per day.