Chapter 44 - Graywater treatment with pelletized mine water sludge

Abstract

In this new chapter, precipitated sludge (ochre) obtained from a mine water treatment plant was considered as an adsorbent substance for pollutants, since ochre is relatively free from problematic levels of toxic elements, which could impair on the quality of water to be treated. Artificially created ochre pellets from mixing Portland cement with raw ochre sludge were utilized to remediate either high (HC) or low (LC) contaminated synthetic graywater (SGW) in mesocosm-scale stabilization ponds at 2- and 7-days contact times under real weather conditions in Salford, England. After a specific retention time, treated SGW was agitated before sampling to evaluate pollutant removal mechanisms (other than sedimentation), such as adsorption by ochre pellets, before replacing the treated water with new inflow SGW. Readers of this chapter will learn about results showing that cement-ochre pellets have a high ability to adsorb orthophosphate-phosphorous (PO4-P) significantly (P<.05) by 70.7% and 56.0% at 7-days contact time for HC-SGW and LC-SGW, respectively. After the experiment, an analysis revealed that elements such as boron (B), cadmium (Cd), magnesium (Mg), manganese (Mn), nickel (Ni), and zinc (Zn) accumulated significantly (P<.05) within the ochre pellets. The notable accumulation of Cd within ochre pellets reflects the significant (P<.05) remediation of graywater during the first 35 and 20 successive times of treatment for HC-SGW at 2- and 7-days contact times, respectively. Cadmium was still adsorbed significantly (P<.05) during the treatment of LC-SGW. However, the calcium (Ca) content decreased significantly (P<.05) within ochre pellets treating both types of graywaters due to mobilization. The corresponding increases of Ca in graywater were significant (P<.05).