SLURRY TREATMENT WITH FOOD INDUSTRY WASTES FOR REDUCING METHANE, NITROUS OXIDE AND AMMONIA EMISSIONS

Abstract

Livestock manure is the main source of ammonia (NH3) emissions and an important source of greenhouse gases (GHG) especially methane (CH4) and nitrous oxide (N2O). Ammonia emissions contribute to eutrophication and acidification of water, soils and ecosystems. The greenhouse gases contribute to the global warming. These gaseous emissions can be reduced by controlling the pH-value of manure. Acidifying the manure can reduce CH4, N2O and NH3 emissions. Inorganic acids are feasible, but have several disadvantages, e.g. soil contaminants. The use of organic acids is an efficient but expensive method; therefore using the food industry wastes which already contain organic acids is highly feasible. The objective of this research is to investigate the effects food industry wastes as manure additives on the emissions of CH4, N2O and NH3. Dairy cattle manure was treated with food industry wastes (whey and waste of citrus and orange juices industry) and the gas flux of CH4, N2O and NH3 were quantified using a specially designed gas detection system which consists of several flasks and a multi-gas monitor. The results showed that the gas fluxes emitted from manure treated with waste of citrus juice industry were 13, 0.219 and 2.523 g m-2 day-1 for CH4, N2O and NH3 respectively. The gas fluxes emitted from manure treated with waste of orange juice industry were 13.58, 0.223 and 2.581 g m-2 day-1 for CH4, N2O and NH3 respectively. The gas fluxes emitted from manure treated with whey were 17.45, 0.279 and 3.063 g m-2 day-1 for CH4, N2O and NH3 respectively. The gas fluxes emitted from the control sample (mixture of manure and water) were 58.21, 0.347 and 18.9 g m-2 day-1 for CH4, N2O and NH3 respectively. Consequently, manure treatment with food industry wastes enabled high reduction rates of gaseous emissions from manure.