ISSN: 1659-2751



Stabilization of Septage from a Small Community with Effective Microorganisms


In Costa Rica, the most common system for management of sewage is the septic tank. The material that accumulates, the septage, contains biosolids and pathogens that can have a negative effect on the environment if it is not managed correctly. The objective of this project was to use Effective Microorganisms (EM-1) to stabilize septage from the cafeteria’s septic tank at EARTH University. Six replications of three treatments of activated EM (EMa: 0 %, 2.5 %, and 5 %, v/v) were incubated anaerobically and the samples were analyzed destructively for various parameters every three days for 15 days. In both experiments a positive effect of EMa at all concentrations, as compared to the treatment without EMa, was observed in the analyses of the samples. Without EMa, the septage had the characteristic fecal odor throughout the entire incubation whereas the samples with the EMa treatments had a characteristic odor of fermentation. With the EMa treatments it was possible to eliminate the coliforms from the samples. As well, a reduction in BOD5, COD, and total solids was observed. After three days, in the samples treated with EMa, the level of BOD5 was lower than the permissible level of <300 mg L-1. However, after 15 days of anaerobic incubation, the levels of COD and total solids were still in excess of those permissible by law for discharging the water into the environment (<1000 mg L-1 and <2000 mg L-1, respectively). The results showed the effectiveness of EMa for stabilizing septage so that it can be used as a source of nutrients in agriculture.

Key words: Activated EM (EMa), coliforms, stabilization, BOD5, COD, septage, Effective Microorganisms (EM-1), pathogens, total solids.

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