Levels of treatment achieved using effective microorganisms in surface and waste waters

Abstract

Effective Microorganisms (EM), a combination of decomposing microorganisms, are extensively used in many parts of the world but their success has not been thoroughly assessed within a Southern African context. Their purposes, mostly employed heuristically, include (a) the treatment of raw, polluted and municipal wastewater; (b) recycling of waste in livestock industries; (c) commercial composting of green wastes, garbage and other organic matter when used as compost inoculants; (d) helping to mitigate the effects of acid rain on crops, vegetation, water and soil; (e) reduction and/ or elimination of methane and harmful gas production in landfill sites; and (f) controlling odour and flies in landfill sites and other places where odour and flies are a problem (e.g., livestock industries). There are limited scientific publications on the subject and hence limited empirical evidence exists as to the efficacy of EM. In addition, limited empirical evidence exists as to under what conditions EM can be optimally employed. This study investigated EM by (a) undertaking an extensive literature research on the subject, (b) analysing the following physical and chemical parameters of raw water from different points of Zoo Lake in Johannesburg that had been regularly dosed with EM: pH, conductivity, turbidity, total suspended solids (TSS), ammonia, phosphates and heavy metals and (c) laboratory experiments under aerobic and anoxic conditions, analysing the same physical and chemical parameters (as done for the lake) of polluted municipal wastewater that had been dosed with EM. The results from the study showed a significant decrease in turbidity (for the aerobic and anoxic experiments), ammonia and phosphates (for the aerobic experiment). The decrease in turbidity and phosphates was attributed to the EM but not that of ammonia as the control also decreased in the same manner. As such, the levels of treatment achieved by EM on surface and wastewaters were considered to be low as only two (turbidity and phosphates) out of seven parameters measured showed significant decreases. Based on this research, it is anticipated that better treatment efficiencies may be realised by combining EM with other complementary microbiological treatment agents and this is suggested for future research.