Determination of odour emission at compost plant based on electronic nose and GIS

Abstract: Three main styles of treatments used in the municipal solid wastes treatment process are compost, landfill and incineration. Composting is an effective treatment for organic solid waste to produce fertilizer. But it always produces a certain amount of leachate and gaseous pollutants during the process, which induces odorous nuisance problems. The malodorous gas produced during composting is an important factor affecting the environment, which often lead to complaints by residents from surrounding area and has negative effect on application of composting technology in municipal solid waste disposal. The odour emission problem from composting plant must be considered carefully.In the research, sampling locations were selected near to the odour pollution sources in a large scale running compost plant (treated more than 1000 tons rubbish per day) by preliminary investigations and GPS (global position system) technology which was used to grid distribution of test points in the research area. The odour concentration were measured at the place neared the emission points of the plant and at sampling sites in the downwind and upwind directions of the facilities by electronic nose under normal weather conditions during 30 days of the research period. Based on large amounts of data obtained at the test points in the area during the research period, tension spline interpolation method of GIS technology was used to calculate the values of the points that have not been tested on the odour emission direction. Then intensity curve of odour pollution in the region was plotted based on the values generated from GIS software. It can be intuitively understood the distribution and concentration gradient downward trend of odour pollution from emission points of composting plant.Two major odour release points were found at the composting plant from the odour intensity distribution map. One point located near fermentation workshop of the plant, intensity value measured by electronic nose was 2465. The other point located near the biofilter of the plant, intensity value measured by electronic nose was 2913. Odor concentration of the points were calculated by formula were 840 and 2191 respectively. The value of the sampling point at leachate drainage outward export that near fermentation workshop was far more than boundary concentration values of unorganized emissions that emission standards for odor pollutants (GB14554-1993) specified. The pollution intensity level of two odour release points reached five, and their concentration in air is normally far above the threshold limit value. There also had some odour escape in sorting workshop of the composting plant during research period.It is determined that the composting plant is prime odour released point that affected the surrounding environment by detection and comparative analysis of the odour concentration data on a wider region of surrounding area near the composting plant. The biofilter is the main odour pollution sources of composting plant. The results show that it is difficult to decrease the odour pollution of composting plant only by using biofilter at the last step to treat the waste gas which collected during whole composting process.