A glass house trial to investigate the impact of water treatment sludge and green waste compost to enhance the revegetation of contaminated sites

This study investigated the use of waste amendments (green waste compost and water treatment sludge cake) in improving the nutrient and revegetation status of contaminated soil obtained from a former industrial site that has heavy metal and hydrocarbon contamination. The waste amendments were mixed with the contaminated soil at application rates equivalent to 90 and 180 t ha−1 (wet weight) and placed in plastic pots. The unamended soil serves as the control. Reed canary grass and white mustard were allowed to grow on the amended and unamended contaminated soil in the glass house. After a 30 day growth period, soil nutrients status were observed and found higher in the amended contaminated soil than the control. In the amended soil, organic matter, total nitrogen, total potassium and soil nitrate were highest in contaminated soil amended with green waste compost at 180 t ha−1 and lowest in contaminated soil amended with water treatment sludge cake at 90 t ha−1. Above ground dry mass of reed canary grass and white mustard grown on amended contaminated soil increased by 120 - 222 % and 130 - 337% respectively as compared to the control showing that improved fertility of contaminated soils thereafter, enhanced revegetation.