EVALUATION OF ENVIRONMENTAL IMPACT OF TYPICAL LEATHER CHEMICALS. PART I: BIODEGRADABILITY OF FATLIQUORS IN ACTIVATED SLUDGE TREATMENT

摘要

Leather processing is associated with the employment or many kinds of chemicals which may be used to excess. As a result, a part of the chemicals inevitably remain in the tannery wastewater and form major pollutants. Biological treatment plays a significant role in removing these chemicals from wastewater and biodegradability of these chemicals is directly related to their environmental friendliness. Recently, we have been undertaking a systematic evaluation of the biodegradability of typical leather chemicals so as to characterize their environmental impact as exactly as possible. In this paper, the biodegradation behaviours of six typical fatliquor components, including sulphated castor, sulphated neatsfoot oil, sulphated fish oil, lecithin, chlorinated paraffin and alkyl sulfonyl chloride, were investigated. It has been found that four of them, sulphated castor, neatsfoot oil, fish oil and lecithin, can be effectively degraded by the activated sludge from the wastewater treatment plant of the tannery, which suggests that these four kinds of fatliquors are suitable for use in leather making in consideration of their environmental friendliness. However, the two other kinds of fatliquors, chlorinated paraffin and alkyl sulfonyl chloride, cannot be degraded by activated sludge and the presence of alkyl sulfonyl chloride in wastewater will lead to poisoning of the activated sludge, which indicates that these two kinds of fatliquors should be limited in use.