Bacteria Screening with Sufficient Nitrate Extraction from Wastewater

Abstract

Search for effective biological strain for use to remedy water pollution has been limited. This study was performed to search for effective bacteria capable of extracting nitrate from wastewater. Samples from abattoir inside (Abi) and abattoir outside (Abt), fishpond of kwalkwalawa (Fpk) and mabera fishpond (Fpm) wastewater were used. Using conventional standard plate technique as 1.96×107 cfu/ml (Abi) had highest bacteria count while 1.05×107 cfu/ml (Fpk) had minimal. The obtained pure colonies were morphologically and biochemically characterized including two Enterobacter specie, Proteus and Pseudomonas specie. The isolated organisms were used as a test organism for the removal of nitrate present in high nitrate containing medium. Prior to the extraction, the wastewater samples were physicochemically analyzed using parameters like color, odor, pH, alkalinity, hardness, temperature and nitrate. For nitrate extraction, bacteria were inoculated in a separate tubes containing nitrate broth, incubated in a rotary shaker 150rpm at 37°C for 16hrs. The supernatant from 10minutes centrifuged culture were used for nitrate removal evaluation after a series of reaction and stop using spectrophotometer at 420nm. The absorbance 0.732 proteus specie after estimation of nitrate in a medium was maximal while Enterobacter specie 0.574 was minimal. Meanwhile, two of the Enterobacter specie has similar absorbance 0.012 while Proteus and Pseudomonas species had 0.016 and 0.010 respectively in the nitrate concentration removed within the media. The nitrate present in the medium was compared with a known standard curve prepared with NaNO3 at 100-1000 ppm. The result indicated that bacteria from fish pond wastewaters had highest potential for extracting nitrate and that inherent bacteria are capable of removing pollutant nitrate and the bacteria may be able to remove nitrate efficiently if genetically engineered.