Biofilter development

Bio-Fungi Kft has made an investigation about the “Development of special biofilters for closed nitrogen consumption in compost production andfor the protection of environment”. The investment previously supported by frame LIFE project was improved with a technological development. The research and development work costed more than 125 million forints whose 50% was supported by KPI and MAG Zrt. As a result of the successful work, the company had marketable technology and knowledge.

The mushroom cultivation has been one of the most successful branches of the Hungarian ghorticulture and closely related to the mushroom growing, the compost production is also developing very intensively and successfully. Our company puts a special emphasis on founding its mushroom growing and compost production units to be suitable for the existing environmental regulation.

The compost production is an environmentally friendly activity, as there is a possibility for the efficient processing of an amount of agricultural by-products. In Hungary, however the quantity of ammonia emitted from the factories causes serious problems and its consequence, the smell emission and stench pollution. The settlements near the factory can be relieved with the introduction of internal technologies which has been already realized by our company. The goal of the current development is to filter those sulfur compounds and ammonia leaving from compost operation by oxidizing bacteria treated biofilters and to recycle the filling material containing nitrates and nitrites in the mushroom production as a nitrogen source. This enables us to realize uniquely a closed nitrogen balance of our company.

We create a certain circulation of nitrogen in the compost production reducing the costs of enrichment of mushroom compost. We need to develop such a filling material that can be reused in the process of mushroom compost and we have to drench it with a bacterial culture that can transform ammonia and sulfur compounds to compounds useful or neutral in the compost production.

The main goal of our experiment is to develop a special biofilter filling material for our already existing – so-called indoor – operating unit which can absorb the unpleasure smells of button mushroom compost production (ammonia, sulfur hydrogen or other penetrating smells) with the help of its special bacterial culture.

Our biofilter unit is built on one step of our technology,  the green compost production, on the so-called big bunkers. The material runs entirely through them and according to our experience in that phase is the biggest the smell pressure on the environment. Our further goal is that the filling prepared from agricultural waste and other additives (urea, peat) together can be used in the technology of compost production after the exploration of ammonia and bacteria with minimal material loss instead of complicated and very expensive destruction. It needs a fundamental and compiled research because many respects must be considered together and the optimum of all these must be sought.

In the previous two-year period all the studies have been made that were taken in the subsidy contract. The completed developments revealed today a strong decrease in the odor emission which was also confirmed by workers of the company. But we could not be satisfied with this. Questionnaires were completed by the people living in neighbourhood of the plant from the beginning. Besides giving their names and addresses they have given feedback of what time of the day they smelled and how much it bothered them. They had to characterize whether the smell remembered ammonia, rotten egg, soil, fertilizer or something else. From this survey, it was found that the odor emission was disturbing mainly early morning and late afternoon . The smell reminded the residents primarily to ammonia odor of manure generated during composting the stable manure.

The questionnaires were the tools of informing the population in the area. We reported in detail on the development phases as we had to make the residents understood regarding the unsuccesful smell decreasing by bacterial and filling suspensions that it does not come from the imperfection of technology but it is part of the research. In the second year of the development and research, the questionnaire reported the obvious success of the research. The residents reported on the significant reduction of the odor, the decreasing of frequency of emissions. Of course there were some residents who wanted to express their dissatisfaction but in the previous years they were the toughest opponents of our activities trying to get closed our company or to claim damages. These residents have difficulties to stop viciousness and accept the failing of indemnization. But they have to realize over time, they have no reason to complain.

We consider as the largest professional conclusion that the micro-bodies in the gas scrubbing system can be continually confirmed which are mainly responsible for the oxidation process of the biofilter and for the reduction of odor. These micro-bodies are refreshed in all three months to maintain the high level of the cell number. At the same time on long term the operation of the technology is allowed by using the used biofilters as a raw material in the compost production without and negative influence on the quality of the final product, of the mushroom compost.