Minimizing the use of water for processing by reusing and recycling it, is done in two or more successive stages. Harvesting of rainwater to meet water requirements. Treating hot water and effluents before releasing them into rivers and ponds. Treatment of industrial effluents can be done in three phases: Primary treatment by mechanical means. This involves screening, grinding, flocculation, and sedimentation. Secondary treatment by biological process. Tertiary treatment by biological, chemical, and physical processes. This involves the recycling of wastewater.