The pilot-scale mulch-tower systems with resorption beds (the MT-RBs) for greywater
treatment became operational in six low-cost houses in Buffalo City Municipality, South
Africa in February 2009. Treated greywater was used for groundwater recharge. Residents of
the houses were in charge of the day-to-day operational maintenance of the MT-RBs. The
municipal officials were responsible for project oversight and major repairs. The authors
performed the chemical and microbiological analyses; and provided technical advice.
Treatment performance and biomass composition of the MT-RBs were monitored between
February and May 2009, and in August 2010. In 2009, 33 % of the MT-RBs were in good
overall physical condition. Clogging of and bursting of pipes did occur on several occasions.
The average concentrations of faecal coliforms, the total bacteria, the total fungi and the total
actinomycetes in the mulch dry matter were (in 106
CFUs/gram dry matter): 0.05 to 2.71, 5.0
to 72, 0.24 to 570 and 0.075 to 350, respectively. Mulch layers in MT-RBs contained
cockroaches (Periplanetta americana, Blatella germanica), spiders (Smeringopus pallidus,
Laterodectus geometricus), mothflies (Psychodidae sp.), sap beetles (Nitidulidae sp.), and
slugs (Deroceras laeve, Lehmannia sp.). No pest infestations of the houses or evolution of
odours were observed. There was limited removal of COD, NO3-, PO4 3-, SO4 2- or faecal
coliforms from greywater. Complete breakdown of all MT-RBs was observed in August
2010. Reasons for treatment breakdown and possible remedial strategies are discussed.