Abstract: A process for clarifying and reclaiming industrial working fluids and/or outdoor working locations such as oil and gas well working fluids and pits. A treating agent is added to the fluid in an amount exceeding its solubility therein to precipitate soluble contaminants and to form a layer of treating agent over a lower layer of sludge at the pit bottom comprising insoluble contaminants and the precipitates. The layer of treating agent compresses the sludge and serves as a filter/barrier to increase the amount of overlying clarified fluid which can be collected. Following separation of the clarified fluid for disposal or reuse, the sludge is solidified by adding a further treating agent. The process is particularly suited for use in oil and gas well exploration wherein the treating agent is a particulate material including lime.