Cleaning process of abattoir wastewater with focus on bacterial pathogens
This study was conducted at the City Abattoir in Kampala, Uganda to evaluate the cleaning process, with focus on bacterial pathogens, in a pilot scale integrated bioprocess. This consisted of four steps: anaerobic sequencing batch reactors; aerobic/anoxic sequencing batch
reactors; a high performance temperature controlled methanogenesis digester and a constructed wetland. The objective was to determine if this type of cleaning process could be used to clean wastewater from abattoirs in a satisfactory way.
The indicator organisms for faecal contamination, Escherichia coli and Enterococcus spp. were used to investigate in what numbers bacteria could be found in the untreated wastewater and how much that was reduced in the different steps of the cleaning process. The water was
analysed for Salmonella to see if human pathogens could be found and could survive the different steps of the treatment process. Antibiotic resistance analyses were also performed on the E. coli samples to see if any resistance could be found and if there was any variation of this parameter in the different treatment steps.
Five samples from the untreated water and from the different treatment steps were collected at five different occasions. The results from the study was that it seems that this type of cleaning plant can be used to decrease the numbers of bacteria in wastewater from abattoirs to a great extent though further decrease in bacterial numbers are needed before the water could be used for irrigation of edible crops or drinking. The most important cleaning step seems to be the anaerobic sequencing batch reactors.
No Salmonella was found in any samples but the human pathogen Shigella was found in several samples including from the final steps of cleaning. High levels of antibiotic resistance were only found in the isolates from the constructed wetland. It is hard to draw any conclusions from this result since the constructed wetland hadn?t been functioning as it was supposed to be when this study was conducted.