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.
