Constructed Wetlands for Industrial Wastewater Treatment

19Dewatering of Industrial Sludge in Sludge Treatment Reed Bed Systems

S. Nielsen and E. Bruun

Orbicon A/S, Ringstedvej 20, Roskilde, Denmark

19.1 Introduction

Sewage sludge results from the treatment of wastewater originating from many sources including homes, industries, agro-industries and street runoff. Sewage sludges contain nutrients and organic matter and, due to these soil benefits, they are widely used as soil amendments. The beneficial effects of sludge application for agriculture and/or environmental purposes (forestry and land reclamation) are well known and documented (e.g., [1] and references therein). The use of organic wastes in agriculture is considered a way of maintaining or restoring the quality of soils, enlarging the slow cycling soil organic carbon pool. Sewage sludge, however, also contains contaminants including metals, pathogens, and organic pollutants [1, 2]. A wide variety of undesired substances, such as potentially trace elements and organic contaminants, can have adverse effects on the environment.

The production of sewage sludge has increased steadily, due to the growth of population connected to centralized wastewater treatment and the implementation of more strict environmental regulation [3]. For example, the yearly production of municipal sludge in the European Union (EU) – estimated to 5.5 million tons in 2005 – is expected to reach a production of 13 million tons of dry solid (t ds) by 2020 [4]. Sludge production from industry, food-industry and ...