Sediment Oxygen Demand of a Leachate Pond at an Offshore Municipal Solid Waste Disposal Site 2 Years after the Site Was Closed

Shogo Sakita,Jun Nishimoto,Kazuyuki Nishimura

doi:10.4236/gep.2018.64011

Abstract

Various water quality parameters of a leachate pond at an offshore municipal solid waste disposal site were monitored. The pH, dissolved oxygen (DO), and water temperature at the bottom of the leachate pond were measured during Sep. (the 1st period) and Nov.-Dec. (the 2nd period) of 2011. The results suggested that the stratification of water temperature in the pond had gradually broken down due to convection occurring between the end of the 1st period and the 2nd period. The pH was almost constant at 10 - 11 during the 1st period and was approximately 11.5 during the 2nd period. The DO was almost zero during both periods. An anaerobic batch experiment with sampled sediment was undertaken to elucidate the mechanism of material leaching from the sediment. DO decreased under all experimental conditions. With respect to oxidation reduction potential (ORP) and total sulfide in addition to DO, the condition most closely mimicking that of the site became the most anaerobic. The average sediment oxygen demand, SODave, was calculated using a brief numerical model based on batch experiment data. The SODave was 1114.7 mg/m2/d, indicating that at least 434 g/d of oxygen must be supplied to the leachate pond to maintain the DO.

Highlights

In Japan, approximately 80% of municipal solid waste (MSW) is incinerated, both to reduce its volume and for sanitary treatment [1]
The results suggested that the stratification of water temperature in the pond had gradually broken down due to convection occurring between the end of the 1st period and the 2nd period
The pH, dissolved oxygen (DO), and water temperature at the bottom of a leachate pond at an offshore MSW disposal site were measured in order to better understand factors affecting pond water quality following site closure

Summary

Introduction

In Japan, approximately 80% of municipal solid waste (MSW) is incinerated, both to reduce its volume and for sanitary treatment [1]. In urban areas, finding new sites for final disposal of wastes has become increasingly dif-. It is necessary to develop strategies to manage MSW disposal sites in a more environmentally safe manner and to promote the reduction, reuse, and recycling of wastes at both the technological and legal levels. Leachate discharged from a MSW landfill must be treated appropriately in accordance with its quality and volume [2]. Complaints regarding leachate color and/or hydrogen sulfide odors can be lessened by careful management of leachate pond water quality. It is necessary to consider measures that will prevent deterioration of pond water quality

Methods

Results

Conclusion