COLOUR REMOVAL BY ADVANCED OXIDATION TECHNIQUES

Abstract

The increase in the production of industrial goods has over strained the assimilative capacity of our water, land and atmosphere. Pollution problems caused by the pulp and paper mill wastewater have been one of the most important amongst common environmental problems. The most noticeable characteristics of the effluent from the pulp and paper industries is colour. Colours not only causes the bad aesthetical effect but also reduce the self-purification capacity of rivers and recognized as dangerous to whole aquatic ecosystem adversely. The colour of the pulp and paper mill wastewater, normally varies from brown to dark brown, is mainly due to the presence of lignin and its derivatives. The pulp and paper mill wastewater are frequently treated by biological treatment process such as aerated lagoon and activated sludge processes. However, these processes are effective in the reduction of BOD, COD and Suspended Solids but .these are not suitable for colour removal. Many of the current organic control unit processes have disadvantages. Coagulation and settling produce sludges, air stripping causes air pollution, and adsorption onto granular activated carbon involves regeneration of the adsorbent to renew the adsorbing surfaces. Oxidation, on the other hand, if carried to completion, truly destroys the organic compounds, converting them to carbon dioxide, water, and inorganic ions. Thus, this is an attractive concept.