Abstract
Ocean dumping of municipal sewage sludge (MSS) that was treated in wastewater treatment plants in the Republic of Korea (ROK) began in 1993 and has sharply increased thereafter; this deteriorated the benthic environment of the dumping sites, consequently necessitating relevant policies to be developed to reduce dumping. This review introduces the outcomes of policies used to phase out ocean dumping of MSS in ROK and provides a method for improving contaminated environments. We first review a previous report submitted under the London Protocol in 2016 and then provide additional data collected since then. In addition, we introduce a scientific research result that reduced the concentration of harmful substances in the dumping sites by capping the dumping area. ROK established policies to phase out the dumping in 2006, which had immediate impacts, with dumping of MSS terminated in 2012. These policies were then expanded to terminate dumping of all types of sewage sludge in 2016, due to the fast and strict application of actions based on intergovernmental cooperation and societal consensus. In addition, the capping method that covered the contaminated sediments with dredged materials was effective. The success of the evaluated policies and research could be effectively applied to areas with similar circumstances.
Highlights
Sewage sludge is an end-product of primary and secondary treatments of sewage effluent arising from urban sources and may contain high concentrations of heavy metals and persistent synthetic organic compounds, depending on its origin [1,2,3,4]
The LP was organized to protect the marine environment from human activities under the International Maritime Organization (IMO), and it has focused on a precautionary approach to environmental protection from the dumping of waste or other materials [7,8]
The Ministry of Oceans and Fisheries (MOF)’s plans and corresponding actions were effective, as they led to termination of ocean dumping of municipal sewage sludge (MSS) in 2012 and further reduction of the amount of other sludges in the following years until all types of sewage sludge were banned from ocean dumping in 2016
Summary
Sewage sludge is an end-product of primary and secondary treatments of sewage effluent arising from urban sources and may contain high concentrations of heavy metals and persistent synthetic organic compounds, depending on its origin [1,2,3,4]. The Waste Management Act pronounced a ban on the direct landfilling of MSS in 1997 and went into effect in 2006 These legal measures caused substantial amounts of MSS to be diverted from land filling to ocean dumping. As a consequence of this increased influx of MSS, substantial enrichments were observed for trace metals including Cr, Cd, and Pb in the surficial dump site sediments, and this has affected the distributional patterns of benthic species in dump sites [13,14,15,16,17] The habitats at these dump sites have been negatively impacted by anthropogenic activities, resulting in considerable changes to the structure of these ecosystems. This led to widespread awareness of environmental damage caused by the ocean dumping of MSS that evolved into a major social crisis, producing intense social conflicts, which provided a key motivation for establishing the policy to phase out ocean dumping of MSS [12]
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