FEASIBILITY EVALUATION OF THE EFFICIENT VERMISTABILIZATION FOR ORGANIC WASTE USING ORP AND ALKALINITY AS A FEED CONDITION

Son, Heui-Jeong; Ha, Sang-An; Sung, Nak-Chang; Kim, Hyeong-Seok; Lee, Yong-Heui

Environmental Engineering Research 1999;4(4): 277-282.

Heui-Jeong Son¹^†, Sang-An Ha¹, Nak-Chang Sung¹, Hyeong-Seok Kim², and Yong-Heui Lee³

¹Department of Environmental Engineering, Dong-A University, 840, Hadan-Dong, Saha-Gu, Pusan 604-714, Korea
²Department of Environmental Science, Silla University, Kwaebop-Dong, Sasang-Gu, Pusan 617-736, Korea
³Department of Civil Engineering, Yangsan College, 105-1, Myeongkok-Dong, Yangsan City, Kyeongnam 626-040, Korea

Corresponding Author: Heui-Jeong Son ,

Received: August 13, 1999; Accepted: October 13, 1999.

ABSTRACT

The property changes of various organic wastes including alkalinity and ORP (oxidation and reduction potential) were monitored during the waste ripening under aerobic condition, and then the percentage of earthworm survival according to the ripening degree of the waste was observed. The relationship between the changed waste properties and the earthworm survival was developed by a nonlinear regression. The important properties of organic waste ensuring the efficient vermistabilization, in which over 70% of the earthworm could be survived, were estimated as -3.6mV of ORP and 950mg/L as CaCO₃ of alkalinity. However, the change of alkalinity in the ripening waste closely depended on the change of ORP and their relationship could be expressed as an exponential function. This means that the feasibility of the organic waste for efficient vermistabilization could be evaluated by either of alkalinity and ORP of the waste. However, the initial ORP of the waste satisfying both conditions of alkalinity and ORP was more tightened to +17.5mV of ORP. The earthworm feed index was defined by non-demensionalizing the percentage of the earthworm survival, based on the 70% of the earthworm survival. The index might be used for the evaluation of feasibility of vermistabilization for an organic waste.

Keywords: vermistabilization | earthworm | organic waste | ORP | alkalinity