Effective microorganism

An effective microorganism (EM) refers to any of the predominantly anaerobic organisms blended in commercial agricultural amendments, medicines and nutritional supplements based on the trademarked product originally marketed as EM-1 Microbial Inoculant, aka Effective Microorganisms and "EM Technology". These blends include:

• Lactic acid bacteria: Lactobacillus casei
• Photosynthetic bacteria: Rhodopseudomonas palustris
• Yeast: Saccharomyces cerevisiae
• Others: beneficial microorganisms that exist naturally in the environment may thrive in the mixture.

EM Technology is purported to support sustainable practices in farming and to improve and support human health and hygiene, composting and organic solid waste management as well as disaster clean-up (the Bangkok floods of 2011, the Southeast Asia tsunami of 2004, the Kobe earthquake, and Hurricane Katrina remediation projects).

Many of the "additives" used for improving the performance of sanitation systems, namely pit latrines, septic tanks and wastewater treatment plants, are also based on effective microorganisms. Despite the claims by manufacturers, the few limited scientific studies which have investigated these additives have come to the conclusion that long-term beneficial effects are not proven.

Origin

The concept of "friendly microorganisms" was developed by Professor Teruo Higa, from the University of the Ryukyus in Okinawa, Japan. He reported in the 1980s that a combination of approximately 80 different microorganisms is capable of positively influencing decomposing organic matter such that it reverts into a "life promoting" process. Higa invoked a "dominance principle" to explain the effects of his "Effective Microorganisms". He claimed that three groups of microorganisms exist: "positive microorganisms" (regeneration), "negative microorganisms" (decomposition, degeneration), "opportunist microorganisms". In every medium (soil, water, air, the human intestine), the ratio of "positive" and "negative" microorganisms is critical, since the opportunist microorganisms follow the trend to regeneration or degeneration. Therefore, Higa claimed that it is possible to positively influence the given media by supplementing with "positive" microorganisms.

Validation attempts

The concept has been challenged and no scientific studies support all of its claims. This was acknowledged by Higa in a 1994 paper co-authored by Higa and soil microbiologist James F Parr. They conclude "the main limitation...is the problem of reproducibility and lack of consistent results.".

Parr and Higa mention soil pH, shading, soil temperature and flooding as factors affecting the interaction of EM with local microorganisms and with each other. The approach that Higa and Parr recommend is maintaining pH and soil temperature within conditions known to be detrimental to negative microorganisms as well as the addition of EM to tip the balance of positive and negative microorganisms in favor of the former.

They dismiss inoculants that include only a single microorganism as generally ineffective due to the uncertainty about the conditions in which a single microorganism would be effective. They cite the acknowledgment by the scientific community that multiple microorganisms (as in the case of Bokashi, invented and marketed by Higa) in coordination with good soil management practices positively influence plant growth and yield.

Lwini and Ranamukhaarachchi published in 2006 a paper that discusses biological controls of bacterial wilt disease and showed that EM and EM Bokashi were most-effective as bio-control agents. Yamada and Xu examined the use of EM in making organic fertilizers. Hui-Lian Xu studied photosynthesis and yield of sweet corn, physiological characteristics in peanuts, and fruit yield and quality of tomato plants. Daiss, et al., looked at pre-harvest and post-harvest applications of EM-1.

Many earlier papers were on EM-X Rice Bran Supplement, a product sold for human consumption. Chui, et al., studied the apoptotic potential of microorganisms. Datla, et al., and Ke B. examined antioxidant-related microorganisms.

The use of EM in the bokashi-intensive composting process for home kitchen waste has been in use in Christchurch, New Zealand for years, backed by the local city council.

Use in sanitation systems

Background

Effective microorganisms are advocated for use in sanitation systems, in particular in pit latrines and septic tanks. The concept has similarities to that of "pit additives" or "septic tank additives" although EM proponents claim that EM includes a much wider range of constituents than most such additives. Most of these additives claim EM aspects, although some are simply used to improve odor or to reduce fat build-up. The products, consisting of packaged micro-organisms or enzymes or both, are marketed for their ability to either reduce the pit or septic tank filling rate with fecal sludge, or to decrease material volumes.

It has been estimated that in the U.S. more than 1,200 septic system additives were available on the market in 2011. However, very little peer-reviewed and replicated field research exists regarding the efficacy of biological septic tank additives.

Claimed benefits

The claims frequently made by manufacturers or sales personnel about these additives include:

• The products contain micro-organisms that can biologically break down the material in the pit to harmless compost products.
• Nutrients present in the additive ensure optimal growth conditions for micro-organisms to break down pit contents.
• Additives stimulate the micro-organisms in the pit accelerate sludge breakdown.
• Aerobic micro-organisms create aerobic conditions in the pit that result in rapid degradation and reduced odor.
• Non-pathogenic bacteria out-compete and/or eat pathogenic microorganisms.
• Odours are reduced as a result of aerobic breakdown.

However, South African research during 2010-2012 as well as Netherlands research in 2013-2014 conclusively showed that it is very unlikely that such claims are valid. The quantity of bacteria introduced to the pit or septic tank by dosing additives turned out to be insignificant compared to the number already present.

Use in wastewater treatment plants and septic tanks

Supporters claim that adding effective organisms to wastewater can result in significant effluent quality improvement, such as reduction in sludge build-up, reduction of organic load or pathogen concentrations and odor reduction. One source claims that EM can reduce hydrogen sulphide and ammonia production.

Results from studies around the world indicate that:

• There is no reliable evidence that addition of EM solutions to wastewater prior to treatment has a significant effect on pathogen concentrations.
• The evidence on the effect of EM solutions on settleability of solids and reduction in effluent BOD and SS is mixed. Under some circumstances, it appears that adding EM can have some effect on both BOD and SS concentrations but the effect is not large and is not proven.
• The available evidence suggests that any lasting effect of EM is dependent on regular application of EM organisms combined with good maintenance of the treatment technology. This will require (a) a reliable supply chain for the EM material and (b) management systems that ensure that the EM material is added regularly and on schedule.

While it is possible that EM techniques can lead to some improvement in effluent quality, it is unlikely that the improvement obtained will be sufficient to allow effluent uses that would not have been possible if EM had not been added. In particular, it seems that any claim that EM use can make otherwise ‘unsafe’ effluents from primary and enhanced primary treatment process ‘safe’ is unlikely to be justified.

Australia

Australian scientists investigated the effect of the addition of EM to a wastewater treatment plant and a number of septic tanks. Their aim was to test the hypothesis that EM reduces sludge volumes. They found significant reduction in pH levels at the wastewater treatment plant together with improved settlement of sludge but with a significant increase in organic matter (measured as biological oxygen demand). Their results for the septic tanks showed a homogenization of conditions in the tanks after EM application, which they suggested was due to domination by a particular type of micro-organism. However, they found no reduction in suspended solids concentration in the effluent and concluded that there were not sufficient changes in sludge volume in the wastewater treatment plant or suspended solids in the septic tanks to indicate a clear benefit from the use of EM in wastewater.

Orangi Pilot Project in Karachi, Pakistan

A project in Karachi, Pakistan called the Orangi Pilot Project (OPP) has beeing making use of EM technology. The OPP promotes a treatment technology comprising a two-chamber tank. The first of these acts like the first compartment of a septic tank while the second is filled with gravel to provide filtration. It is not clear whether flow through the second compartment is upward or downward. This arrangement has some similarities to baffled reactor designs promoted by the German NGO BORDA, although standard BORDA designs provide more chambers, arranged in series and with all after the first chamber operating in an upward flow mode. The baffled reactor design is one of a number of ‘DEWATS’ (decentralised wastewater treatment systems) wastewater treatment technologies promoted by BORDA. All operate anaerobically and are examples of what might be termed enhanced primary treatment. If maintained well, enhanced primary treatment modules should perform better than a well maintained conventional septic tank but will still produce an effluent with high pathogen levels and relatively high biological oxygen demand and suspended solids concentrations.

The OPP is using EM techniques to improve the effluent produced at these small treatment plants, including the plant that treats effluent from a nursery in Karachi. It has also also supported the installation of several small treatment plants using EM technology in rural Sindh and Punjab. Its partner organization Ali Hasan Mangi Memorial Trust (AHMMT) installed a small EM sewage treatment unit to treat sewage from 300 houses in the village Khairodero in Larkana District. Another eleven are reported to be functioning and more are planned.

During discussions at the Urban Resource Centre in Karachi in late 2011, the late Parveen Rehman of OPP stated that the addition of EM to the inlet chamber of these treatment facilities had resulted in improved effluent quality and a significant reduction in smell. However, it seems that OPP had not attempted to quantify the improvement and had not made any formal assessment of the effect of EM treatment on effluent quality.

US Environmental Protection Agency (EPA)

The US Environmental Protection Agency (EPA) has produced a fact sheet on the use of additives to improve the performance of septic tank treatment systems. This is concerned with biological additives in general rather than EM in particular. The fact sheet concludes that biological additives such as bacteria and extracellular enzymes do not appear to significantly enhance normal biological decomposition processes in septic tanks. They go on to say that ‘some biological additives have been found to degrade or dissipate septic tank scum and sludge. However, whether this relatively minor benefit is derived without compromising long-term viability of the soil infiltration system has not been demonstrated conclusively’. They noted that some studies suggest that material degraded by additives in the tank contributes to increased loadings of BOD, suspended solids, and other contaminants in the otherwise clarified septic tank effluent.

North Carolina, USA

Researchers from the U.S. carried out field experiments in 2011 to assess the effect of additives on the performance of 20 septic tanks. These septic tanks served residences at a mobile home park located in Orange County, North Carolina were used in this study. The researchers distinguished between tanks that were well maintained, poorly maintained and maintained to an intermediate level, defining the level of maintenance in terms of the period since the septic tank had last been desludged (up to 2-3 years for well maintained, 15 – 20 years for poorly maintained and somewhere in between for the intermediate category). They found some reduction in sludge accumulation rates but only for their category of well-maintained septic tanks. A follow up study investigated the impact of three additives on the performance of well-maintained septic tanks. Overall, their conclusion was that there was limited evidence of additive impact on the performance of septic tanks. It should be stressed that these field experiments used additives other than EM and the proponents of EM would no doubt argue that the more varied composition of EM makes it more effective than the additives tested here.

Cost aspects

Based on the research conducted so far, it is fair to say that individuals and local authorities spending money on such additives for their sanitation systems are generally wasting their money. A fifth of South African municipalities indicated in 2011 that they purchased additives as part of their sanitation management programmes but the Water Research Commission in South Africa is advocating against this practice saying the money would be better spent on effective pit sludge management through mechanical emptying of the pit.

As the costs and health risks associated with manual pit emptying are huge, if a product was ever developed which significantly impacted the filling rate of pits, e.g. based on EM, this would be of enormous significance.