Microbiological studies of an anaerobic baffled reactor: microbial community characterisation and deactivation of health-related indicator bacteria

Abstract

This WRC funded project has studied the appropriateness of the ABR (anaerobic baffled reactor) for on-site primary sanitation in low-income communities. A 3,000 L pilot reactor was located at the Kingsburgh wastewater treatment plant south of Durban, South Africa. Feed to the reactor was raw domestic wastewater containing a significant proportion of particulate organic matter. The compartments of the ABR were routinely monitored for pH, COD, and gas production, among other physical-chemical determinants. The microbial population in each compartment was analysed by fluorescent in situ hybridisation, using general oligonucleotide probes for eubacteria and archeae and a suite of 10 genera or family specific probes. Scanning electron microscopy was conducted on the sludge fraction of each compartment. Mixed fractions from each compartment were also analysed for health-related indicator bacteria (total coliforms and E. coli). Results indicated that methanogenesis was not occurring to the expected extent in the latter compartments, and that this was probably due to a hydraulic load limitation. This contrasted with earlier studies on industrial effluent, for which the organic load was exclusively in soluble form. Inactivation of health-related indicator bacteria was less than 1 log, indicating the need for an additional post-treatment of the effluent to protect community health.

Anaerobic Sludge Blanket Reactors

“…Table 5 presents concentrations of pathogens in the sludge. (Chernicharo et al 2001;Dixo et al 1995;Prado et al 2011;Soares et al 2000;von Sperling et al 2002von Sperling et al , 2003Keller et al 2004;Ribeiro et al 2015;El-Khateeb et al 2009;Morsy et al 2007;Trein et al 2015;Gonçalves et al 2009;Dias 2016;Verbyla 2015;Symonds et al 2014;Pant and Mittal 2007;Foxon 2009;Foxon et al 2006;Lalbahadur et al, 2005;Oliveira and von Sperling, 2011;von Sperling and Mascarenhas, 2005;Yaya-Beas et al, 2015) b ND = No data…”

“…1.0 log 10 removal for Salmonella spp., 0.5 log 10 removal for Shigella spp., 1.0 log 10 removal for Vibrio spp in a UASB reactor (Pant and Mittal, 2007) 1.1 log 10 reduction of thermotolerant coliforms in UASB reactors (Oliveira and von Sperling, 2011) 1.0 log 10 reduction of thermotolerant coliforms in an ABR reactor (Lalbahadur et al, 2005) 0.3 log 10 removal of Cryptosporidium oocysts (Morsy et al 2007) 0.42 to 1.30 log 10 for UASBs (Keller et al, 2004;von Sperling et al, 2003;Yaya-Beas et al, 2015).…”