Waste water purification

Abstract

Disclosed is an improved process for the treatment and purification of waste water. Generally the process comprises the use of primary, intermediate, and secondary treatment but tertiary treatment may also be included. Powdered activated carbon is used in the secondary treatment with recycle to any or all of the primary, intermediate or secondary treatment stages. Regeneration of used powdered activated carbon is also provided. In some cases, the improved process for the purification of waste water comprises feeding the waste water to a first clarification zone wherein easily removable solids are separated from the water; passing the effluent from the first clarification zone to a filtration or air flotation zone wherein suspended solids and colloidal matter are separated from the water; passing the effluent from the filtration or air flotation zone to an aeration zone wherein the water is contacted with activated sludge and powdered activated carbon, and oxygen is introduced into the water-sludge-carbon mixture; passing the effluent from the aeration zone to a second clarification zone wherein purified water is separated from the sludge and carbon; recycling a first portion of the separated sludge and carbon from the second clarification zone to the filtration zone effluent; recycling a second part of the separated sludge and carbon from the second clarification zone to the first clarification zone effluent; and passing purified water from the second clarification zone.