Environmentally friendly comprehensive recycling utilization technology of foundation engineering slurry

Abstract

A set of environmentally friendly comprehensive recycling utilization technology was developed to occupy fewer land resources and realize the recycling of engineering slurry. In this study, the engineering slurry was divided into circulating and waste slurries. The technology of “desanding plus reusing of purified slurry and drill cuttings” can be adopted to the circulating slurry, and the technology of “lowering calcium concentration, pH control, flocculation separation, pressure filtration and recycling of wastewater and mud cakes” can be adapted to the waste slurry. For the purified slurry and drill cuttings obtained from the circulating slurry, the former can be directly recycled in foundation engineering, and the latter can be directly used to cultivate grass seeds, with an average germination rate of 62.22%. Wastewater and mud cakes were collected from the flocculating substances after pressure filtration. With the addition of 2% sodium bicarbonate, the wastewater satisfied the mud-making requirements of foundation engineering. Moreover, mud cakes mixed with 30–60% nutrient soil can be used to cultivate grass, with an average germination rate of 72%. The germination rate of Phi alkali grass exceeded 80% in a field trial with drill cuttings from an underground diaphragm wall project, whereas that of ryegrass and slope king grass was 100% with drill cuttings from a geothermal well project. This method can realize the comprehensive recycling utilization of all drill cuttings (or mud cakes) and purified slurry (or wastewater).