Methods to Reduce Malodour Emission from Municipal Solid Waste Fuel

Abstract: Swedish power plants have in general an overcapacity which means that they must import waste from abroad. The imported fuel consists of several types of waste, but the majority originates from municipal and commercial waste. EFO is one of the leading fuel supplying and transport companies in Sweden. The company is owned by eight power plants located all around Sweden. The waste is purchased from other countries and then shipped to Sweden. During the unloading of the ship, when the cargo hatches opens, the malodourous gases will escape and be released in to the air. These malodours can travel quite far and are extremely unpleasant to people who live close by. The aim of this thesis was to suggest ways on how to prevent or reduce the emission of malodours during unloading of bales containing municipal waste. The aim of the project was to determine the causes of malodours, to identify the most common odorants in municipal waste, what properties they have, how they can be affected and how to prevent the formation of them. The problem was tackled by theoretical and practical studies. The theoretical study was a literature study and the practical study was observation at Mälarenergi combined heat and power plant. The results are presented as a number of suggestions for how to prevent or reduce the emission of malodours during unloading of bales containing municipal waste. These suggestions were divide in to the three categories Storage, Unloading and At Port. The suggestions varied from using better sorted waste to researching the possibility to use a portable tent covering the cargo ship during unloading. It was recommended that EFO should use both short- and long-term plans and also conduct further research on other ways to reduce emission of malodours.The suggestions were not tested so it cannot with certainty be determined if the suggestions will reduce or prevent emission of malodour. No laboratory tests were done on the waste. Therefore, the contents and concentrations could not be confirmed. However, it is almost certain that even if there were a slight difference it would not lead to a change of the current treatment process of the MSW. Obviously, there should have been multiple observations carried out at Mälarenergi`s power plant on various occasions and at different weather conditions. Several observations should also have been done on EFO´s other power plants to confirm that the core of the malodour emission problem is the same for all power plants. Basing suggestions on results taken from one instance might not give the correct answer to the problem. Common for malodours found in MSW is that they are formed as a product of degrading MSW. Reducing or stopping the degradation process, will prevent the formation of these compounds. This can be done either by lowering the temperature of the waste bales, altering the pH, decreasing the water content and increasing the level of Oxygen.