Effects of pH Control On Composting of Garbage

Abstract

Composting experiments of garbage were conducted by using a laboratory scale reactor under well controlled experimental conditions and the effects of pH control were quantitatively analysed. In the pH controlled experiment, lime was added to prevent pH decreasing below 7, especially at the early stage of composting. The degradation rate of organic matter in the pH controlled experiment was faster than that without. Nitrogen loss was enhanced by the control of pH value, but the amount of promotion was relatively small. The pH dependency on the activity of microorganisms, which contribute to the composting rate, was investigated by using a liquid medium containing glucose and proteins as nutrients. The optimum pH for the growth rate and the degradation activity of proteins of the microorganisms was in the range of 7-8, while the decomposition of glucose proceeded rapidly at an early stage of composting in a pH range from 6 to 9.