Lacquering plant operating process - uses bio-reactor and membrane separator to regenerate circulated water

摘要

An operating process for industrial lacquering plants involves using a water drizzle or spray to trap paint mist and solvent in the spray booths and/or in scrubbing towers, continuously removing lacquer particles from the water circuit by coagulation, settling or flotation and replacing the circulated water with fresh water at certain intervals. The novelty is that (a) after lacquer particle removal, part of the organic matter-loaded water is continuously passed through an aerated vessel (bioreactor) contg. an adapted microbiological biocoenosis which removes the organic content from the water and thus biologically regenerates the water; and (b) after regeneration, the water is clarified by membrane sepn. in the form of micro- or ultrafiltration and then returned to the lacquering plant. When the circulated water is unacceptably enriched with deleterious substances, the entire polluted circulated water is exchanged with fresh water, the bioreactor and the membrane separator being isolated from the fresh water supplying circuit and the polluted water being stored in a large intermediate vessel. The stored water is circulated between the bioreactor and the intermediate vessel until its chemical oxygen demand is reduced to below the acceptable limit for discharge into drains, the biocoenosis being simultaneously maintained active and, during this period, the lacquering plant being operated with biologically untreated fresh water. After discharge of the treated old water, the bioreactor and the membrane separator are reconnected to the water circuit. USE/ADVANTAGE - Process is used e.g. in vehicle body paint shops. The process permits longer intervals between water replacements and thus reduces water consumption.