Alternative odour control: turning to plant-based micronutrients
New approach designed to stimulate aerobes and anaerobes while inhibiting sulphur-reducing and ammonia-forming bacteria and enzymes
Transfer stations, recycling and composting facilities, similar to many industries ranging from wastewater and sewer to agricultural, can generate strong, “offensive” odours. When located near urban populations, this creates a challenge, especially as North American cities continue to grow in density. Odours can have an impact on small towns, rural residents and on larger urban areas, and property values of residential and commercial development are often affected by the potential/existing/perceived odours coming from neighbouring plants and facilities.
The source-separation of waste for pickup, in which waste is separated into containers for food waste, plastic, paper and refuse, works well, to a degree, for single family home owners. But for condos, apartments and other multi- residential locations, source separation is a significant challenge. Food waste bins, for example, are an identified source of odour in every single/multifamily dwelling.
Meanwhile, the measurement and management of offensive, fugitive odours has grown into a significant part of the environmental sector, spawning innovative technology to address the problem. Drone-based sampling devices have now been developed to measure odours above and around industrial facilities, for example. Overall, there has been significant progress made in measuring, quantifying and in the identification of odours which generate nuisance complaints from the public and regulatory agencies.
Those regulatory agencies are now able to identify the facilities and plants responsible for odour generation and force them to deal with odour-related problems.
Because of all of this, there is now significant incentive to measure and mitigate fugitive, offensive odours in the waste management and composting industries.
Most of the new technology currently being developed is based on chemical breakdown of odours using UV, carbon, ozone and biological filtration.
Other solutions, including oxygenation and aeration of solid and liquid waste collection basins to prevent septic conditions, can be energy-intensive. The least effective method used currently is the use of chemical masking agents – which are often toxic and have human exposure restrictions. Other initiatives and solutions to mitigate offensive odours in industry have been based on the use of biocides to kill the bacterial populations that are responsible for the generation of odours. Unfortunately the use of biocides to kill odour-producing bacteria also kill the non-odour producing beneficial anaerobic/aerobic bacteria which are responsible for the biological breakdown of waste material. Selectively stopping the generation of odours at the source can also be done by inhibiting odour-producing bacteria using selective micro-organism stimulants. Several approaches to this challenge, such as aerating solid/liquid waste streams in order to biologically inhibit the activity of odour-producing bacteria, are costly, energy-intensive and tend to produce large quantities of new biological organic biomass, which in turn must be treated and disposed of.
A new way to control odours – plant-based micronutrients
A new biological, environmentally sustainable approach using plant-based organic micronutrients has been developed over the last number of years. This method is designed to specifically stimulate aerobes and anaerobes and competitively inhibit sulphur-reducing and ammonia- forming bacteria and enzymes.
The main active ingredients in these new micronutrient solutions include plant-sourced amino acids, vitamins and other plant-based organic constituents and trace minerals. The micronutrient solution itself is biodegradable as it is used up by the beneficial bacteria as a food source. These micronutrients, when added to liquid and solid organic waste streams, eliminate the formation of odours at the source. ( Ie., in the biological reactions that are responsible for organic waste degradation.)
When certain micronutrients are added, it impacts the metabolic rate of certain microbial organisms. Recent research has shown that non-sulphur reducing anaerobes and many other types of aerobes are stimulated by plant-based organic micronutrient catalysts to operate at much higher metabolic rates. But, sulphur-reducing anaerobes and ammonia- generating enzymes are unable to utilize the specific micronutrients introduced. As a result, the micro-organisms stimulated by the micronutrient solution out-compete the odour-producing microbes for macronutrients and thereby, by means of competitive inhibition, severely restrict the odour producing microbes in their metabolic activity, resulting in a dramatic decrease in the production of odorous gases. The net impact is that odours are significantly reduced but bacterial breakdown of the organic waste continues at an accelerated rate.
Benefits of biological inhibition of odour-producing bacteria
The biological inhibition of odour producing bacteria has been observed to take place in compost facilities, sewer systems, wastewater plants, septic tanks, lagoons, retention ponds or combined sewer overflow ponds, where plant-based micronutrient solutions have been added. If micronutrient control of odour generation is implemented there is no need to revert to aerating septic systems, tanks, lagoons or ponds, or treatment facilities to control and/or treat odours.
The advantages of biological source control of odours with micronutrients include the elimination of the need for significant infrastructure and space requirements to contain, control and treat odours; it requires 90 percent less capital investment associated with odour control using chemical and/or biofilter infrastructure; and it requires 90 percent less energy demand associated with conventional odour control strategies and technologies, with a significant associated carbon-footprint reduction.
Overall, the use of plant-based organic micronutrients represents a near zero carbon footprint solution to eliminate odours from most, if not all, odour-generating facilities. There is also an immediate return on the investment for micronutrient usage as it replaces or eliminates the costly operation of biofilters, ozonation units, and carbon units.
Treatment of airborne odorous compounds using micronutrients
Plant-based organic micronutrients can also be utilized in misting systems to treat odorous gases generated by nonpoint sources of odours in facility operations like transfer stations, compost and recycling facilities, landfills, garbage collection rooms in commercial facilities, wastewater plants, biosolids processing facilities, and organic material processing facilities like food production plants and/or pulp and paper mills. These micronutrients can also be used to improve capacity and performance of biofilters and wet-scrubbers.
Plant-based micronutrients, when diluted in ratios varying from 100-1000:1, react with airborne odour molecules through chemical oxidation to render the odorous molecules odour-free. The exact mechanism is not fully understood except that when used in this type of application the results in most cases justify the use and cost of the organic plantbased micronutrient solutions, as most off-site odour complaints are eliminated and working environments on site for staff improve dramatically.
These micronutrient solutions contain no masking agents, except in some cases where a tracer fragrance is required, and do not contain any bacteria or enzymes that may be subject to regulatory restrictions. They also do not contain any minerals in concentrations harmful to the environment.
A proven solution
Micronutrient solutions, when added to a given waste stream, inhibit the formation of hydrogen sulphide, ammonia, trimethylamine, methylmercaptans and other non-identified sulphur-reduced organic compounds.
Controlled laboratory studies were recently carried out to measure the effectiveness of these micronutrient products when added to decaying organic waste. For the studies, two reactors with an enclosed head space – a control and test reactor – were set up, each containing 1 kg of decaying food waste.
For the studies, two reactors with an enclosed head space – a control and test reactor – were set up, each containing 1 kg of decaying food waste. The test reactor was treated with a one-time 5-ml dose of a micronutrient solution – Biologic SRC, manufactured and sold by Scicorp International Corp. The reactors were equipped with sampling ports to sample headspace gases and were incubated at a temperature of 30 degrees C to represent warm weather conditions. The reactors were sampled every 12 hours over a five day period. The air bag samples were sent to a certified laboratory and analyzed for the four compounds listed above. The reactors were also subjected to a simple olfactory test by the technician.
Test results showed that the control sample was characterized by a highly putrefied odour. The treated sample, however, was free of any objectionable odours. The analytical results are presented as follows.
The laboratory tests confirmed that a one-time dose was effective over a five day period to suppress the generation of odourous gases by 70 to 85 percent from organic waste incubated at a temperature of 30 degrees C.
These results have significant implications for the source mitigation of odours, from green bins and compost facilities to transfer stations, landfills and wastewater treatment facilities. Further testing has confirmed that solid organic waste degradation rates were increased by up to 65 percent under laboratory and field conditions.
As discussed, micronutrient solutions have also been applied and monitored in misting applications to oxidize and neutralize airborne non-point source odourous compounds. Commercial misting applications in refuse-storage rooms of stores and institutions have achieved 85 to 90 percent reductions in H2S/Ammonia concentrations in the atmosphere. Misting applications in MSW transfer stations, landfill sites, tipping floor and pits in a MSW incineration plant have all also resulted in dramatic odour reduction and elimination of neighbouring odour complaints.
Besides these positive results, the use of a micronutrient solution in misting applications also requires minimal capital investment for infrastructure.
The use of micronutrient solutions for odour-source control and odour abatement and stimulation of beneficial biodegradation mechanisms represents an alternative, innovative, but proven environmentally sustainable approach.
The plant-based micronutrient products utilized in the applications cited in this article are manufactured and sold by Scicorp International Corp under the BIOLOGIC SRC/SRC3 brand. BIOLOGIC SRC products have been tested and are certified non-toxic by TOX Monitor/BSR, Inc. based in Illinois. and are certified within the Ecologo/UL program, North America’s largest most respected environmental standard and certification mark. Additionally, Biologic SCR has recently been branded by a major waste management company and is being marketed as an odour control product for controlling odours from green-bin food waste containers used by households in North America.
This article was originally published in the September, 2016 edition of Recycling Product News, Volume 24, Number 6.