An investigation was carried out to evaluate the effect of EM on wastewater thickened sludge in order to increase and/or control the production of biogas. The sludge was mixed with variable amounts of EM, to study their effects on the wastewater thickened sludge degradation. EM consists of a wide variety of effective, beneficial and non-pathogenic microorganisms produced through a natural process and not chemically synthesized or genetically engineered. EM has a broad application. EM has no adverse effects on and is beneficial to plants, animals, and humans. Sludge samples were mixed with different ratios of EM to determine the optimum mixing ratio that will affect the reaction rate and the generation rate of gases. The mixing ratios ranged between 0.5% and 3% by weight. To simulate the anaerobic conditions, used cells were consisted of reactors connected to gas collectors. Each gas collector was attached to an open jar to receive and measure the volume of water collected due to the pressure of the biogas. The cells were placed in a glass basin equipped with a heater to maintain a constant temperature during the test. Experimental results indicated that the optimum mixing ratio was 3%. In case of using EM in sludge digestion BOD, COD, VSS, and TS tends to decrease by 75.5%, 68.3%, 42.5%, and 38%. On the other hand the reference sample BOD, COD, and VSS decreased by 33.3%, 20.2%, 9.3%, and the TS increase by 17.8%. These findings can be utilized for commercial use to achieve efficiency and flexibility in the process of anaerobic sludge.
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