Environmental applications of Effective Microorganisms: a review of current knowledge and recommendations for future directions.
This article was published in the Journal of Engineering and Applied Science volume 68, Article number: 48 (2021) via Creative Commons license CC by 4.0 http://creativecommons.org/licenses/by/4.0/ and is in the public domain.
This page is sharing the Abstract, Introduction, and Conclusions. The full paper may be read by following this link: https://doi.org/10.1186/s44147-021-00049-1.
Authors: Safwat, S.M., Matta, M.E.
Nowadays, beneficial microorganisms are getting wider applicability. One example is referred to as Effective Microorganisms (EM) having its composition kept a secret. EM is a product in liquid form, which consists of a variety of not only effective and beneficial microorganisms but also nonpathogenic ones, with admirable coexistence between aerobic and anaerobic types of microorganisms. The aim of this narrative review is to provide a summary of the different uses and applications of EM, their applications, their benefits, and the expected results when using them in different applications. This is the first review to focus on the uses of EM in environmental engineering systems and processes such as wastewater treatment processes. Originally, EM was manufactured to be utilized in organic farming, but at the moment, this substance is getting wider applications such as in medicine, environment, livestock sector, forestry, and agriculture. When it comes to the protection of the environment, EM helps in waste deodorization, eutrophication control, and wastewater. Investigation on EM use in water quality restoration, wastewater treatment, the treatment of sludge, and composting has been undertaken by researchers. This review provides an overview of the current situation of environmental application of EM in various fields including water quality, wastewater treatment, sludge treatment, and composting.
Keywords: Bioremediation, Sludge, Environmental biotechnology, Wastewater, Water
Today, beneficial microorganisms (BMs) are now getting wider applicability or uses. BMs, for instance, can be applied to the environment in three main ways namely the single strain, compound strains, and multiple strains with some synergists . The BM functions by catalyzing the decomposition of organic matter in order to not only maintain microbial ecological equilibrium in water and sediments, thus creating favorable conditions for aquatic life, but also maintain dynamic ecological balance among various organisms from all kingdoms . BMs, therefore, perform several functions in microbes’ ecology whether in water and sediments including :
- Adjusting the population of algae in water bodies in order to prevent the deterioration of the quality of water
- Inhibiting the development of fish diseases as well as putrefaction of some aquatic plants during summer
- Bolstering the immune system of aquatic animals, thus enhancing the aquatic animals’ resistance to disease
- Suppressing the harmful effects of oxidation through generating antioxidant substances as well as through the accompanying antioxidant emission of waves (that also suppress harmful effects of oxidation). Additionally, BMs can deactivate the occurring free radicals in living organisms and materials
- Helping overcome the challenges of polychlorinated biphenyl and dioxin
The area of effective disposal of sewage sludge (in a manner that is eco-friendly) is attracting unprecedented growth and development in technological innovations in order to make disposal of waste conform to the strict environmental demands and regulations . One of such technologies is referred to as Effective Microorganisms (EM) having its composition kept a secret . EM is a brand name for the various products developed by Dr. Teruo Higa, who is a professor of horticulture at the University of Ryukyus, a university located in Okinawa, Japan . EM is a product in liquid form and is consisting of a variety of not only effective and beneficial microorganisms but also nonpathogenic ones, with admirable coexistence between aerobic and anaerobic types of microorganisms . Figure 1 shows the EM solution and SEM photo of it. The advantage of EM is that its process of fermentation is natural and not chemically engineered or genetically synthesized . Consequently, EM technology is not only eco-friendly but also plays the actual role of protecting the environment. This is because EM is safe and organic . EM has several beneficial microorganisms such as five families and ten general as well as more than 80 types of aerobic and anaerobic microbes like lactic acid bacteria, photosynthesis bacteria, fungi, actinomycetes, and yeast that work together to make up EM during the manufacturing process and produce a substance that survives in a mixture of EM cultured in a brown solution containing 100 million active microorganisms per milliliter and under the pH level of 3.5 . It is important to note that the photosynthetic bacteria, being one of the major elements of EM, are critical in working synergistically with other microorganisms in reducing the incidence of pathogenic microorganisms as well as supporting nutritional requirements . Through producing certain substances, the microorganisms can survive unfavorable environmental conditions, thus effectively competing with pathogenic and destructive microorganisms and replacing them . It has been demonstrated that EM produces substances that play the role of antioxidants  and thus inhibit harmful microbial species as well as enhance the production/proliferation of organisms that are beneficial to an animal. Moreover, these substances detoxify harmful substances .
Originally, EM was manufactured to be utilized in organic farming, but at the moment, this substance is getting wider applications such as in medicine, environment, livestock sector, forestry, and agriculture . When it comes to the protection of the environment, EM helps in waste deodorization, eutrophication control, and wastewater . Because of the rising interest and applicability of EM, its developers have promoted the technology far and wide . Presently, EM has been adopted by over 100 countries across the globe, not on an experimentation basis but for commercial use as well as environmental management . In terms of composition, EM is commercially available as an EM-1® suspension concentrate, which is utilized as a basic formulation of various EM preparations obtain through sugar cane, molasses, and water’s anaerobic fermentation (EMA), or fermentation of water, sugar cane molasses, and vinegar (EM5), or fermentation of fermentable organic substrate and sugar cane molasses (Bokashi) . EMA and EM5 are spraying substances that are used not only in enhancing soil and manure quality but also in disease control . Theoretically speaking, EM has beneficial organisms that decompose the organic matter into methane (CH4), carbon dioxide (CO2), or other useful substances for growth and reproduction . Therefore, EM, in theoretical terms, is very important in the treatment of wastewater as well as improvement of the quality of water discharged in addition to reducing the quantity of sludge that is produced . Moreover, EM can also treat the leachate that is coming out of the garbage besides removing the foul smell from the decomposing garbage . By applying this technology, the menace of mosquitoes and flies is significantly reduced. In addition, EM technology suppresses the harmful gases produced by decomposed garbage . The species that are majorly present in EM include lactic acid bacteria, which have been identified as crucial in cleaning septic tanks as well as algal control . EM can also help prevent the growth of pathogenic bacteria .
A review of applications of EM in various environmental fields is essential to fill the information gap in the literature. Thus, the main objective of this review is to provide an overview of the actual situation of environmental applications of EM in different fields including water quality, wastewater treatment, sludge treatment, and composting.
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This review provides detailed information about the current environmental applications of EM technology. The research conducted during the time that was taken into consideration in this paper is an indication that the precise EM components are still unidentified. Different opinions, on the basis of the literature with regard to the EM application in environmental bioremediation applications, abound. EM generally revealed good performance in the restoration of the water quality and wastewater treatment, together with sludge volume reduction. The results, nonetheless, failed to turn out good when it comes to composting. It is possible to say, as a general conclusion, that, in certain cases, EM technology has demonstrated to be a very encouraging alternative when it comes to conventional treatment procedures. It is essential to perform further researches regarding the application of EM due to the lack of precise information about its behavior. Studies of several parameters such as temperature, pH, hydraulic retention time, dose, and its performance in aerobic and anaerobic environments should be performed to be able to apply this technology in a full scale.