DOI: 10.14457/tu.the.2014.285
title: Application of microwave technology for treatment of human feces

description: AbstractAPPLICATION OF MICROWAVE TECHNOLOGY FOR TREATMENT OF HUMAN FECESbyTU ANH NGUYEN KIEUBachelor of Environmental Engineering, Ho Chi Minh City University of Technology, 2013Human feces, also known as stool, are the waste product of the human digestive system. They include organic compounds and bacteria. Fresh feces from toilet system are often moved and kept at the septic tanks in the form of sludge. This sludge is treated by many different methods such as anaerobic digestion, aerobic digestion and composting. Incineration is also used, albeit to a much lesser degree. There are some studies that applied the low cost systems as naturally biodegradable using aerated lagoon, combined system for multi-treatment or multiple cesspool series. However, all of them must be operated at high residence time to finish biodegradation process. No study on complete treatment of feces using microwave has been reported to the point that human waste can be discharged/recycled in an environmental friendly and safely way. Thus, this study explores the possibility of re-inventing a decentralized human waste treatment system based on microwave technology. The efficiency of the microwave treatment on human feces, which is related to types of microwave, the amount of sample, shape of the microwave container, additional moisture content, different exposure time and microwave power, was evaluated by monitoring the physical and biological parameters of the feces samples from a septic tank, before and after treatment. When using commercial household microwave without rotation for a sample of 200 g (based on per person usage), 15-20 minutes are required at higher power of 800 and 1000 W to achieve pathogen safe end product. For 1000 g sample, 70 minutes at 1000 W are required to make product safe. However, microwave with rotation proved the uniform effective treatment and the exposure time of 60 minutes (1hour) is enough to achieve volume reduction and also pathogen safe end product at powers of 800 and 1000 W. Moreover, the experiments with similar energy input indicated that longer exposure time attained better results in all aspects. A maximum removal of 9 log unit reductions in pathogens, 100 % moisture removal, and 93% volume reductions can be achieved using commercial household microwave with rotation at 1000 Wh ( 600 W and 100 minutes). The end products become more stable by the process of carbonization increasing the carbon contents and no bacterial propagation was observed in the treated sample even in the presence of water after several days of the treatment. It is conclusively evident that microwave radiation is one of the promising technologies that deserve careful considerations to be used as treatment unit in toilet. The study has also proven that the technology is feasible to treat the human feces to the point where the end products can be discharged or reused in a decentralized fashion.  Microwave technology for a toilet system is both lower in cost and require a smaller space. It is faster, safer, and simpler. Moreover, it can achieve volume reduction, pathogen destruction and making the end products safe for reuse or discharge.