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1. BIODEGRADABILITY EVALUATION OF TYPICAL LEATHER CHEMICALS (II)-THE BIODEGRADATION BEHAVIOURS OF ORGANIC TANNING AND RETANNING AGENTS ON ACTIVATED SLUDGE | |||
Sun Danhong,Shi Bi | |||
Chemical Engineering 13 January 2010 | |||
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Abstract:The biodegradabilities of three kinds of typical organic tanning and/or retanning agents, namely aromatic syntans, aldehyde tanning agents and acrylic syntans, were studied in this paper. The results showed that the biodegradation behaviours of the leather chemicals are closely associated with their molecular weight and structure together with their chemical composition. It is suggested that the employment of organic tanning and/or retanning agents in leather industry might result in different environmental impacts even for the same kind of syntans. The tested four aromatic syntans (SGP, PGP, KWOP and BS) exhibited different but generally low biodegradability. The phenol syntan SGP could not be biodegraded, and the phenol-sulphone syntan PGP exhibited strong inhibitory effects on activated sludge respiration. Comparatively, the naphthalene syntan BS and the phenol syntan KWOP showed somewhat better biodegradability. In the case of aldehyde tanning agents, both formaldehyde and glutaraldehyde are toxic to activated sludge organisms, and comparatively the latter is potential to cause more severe environmental problem when it was used in leather industry. However, an aliphatic aldehyde product, namely syntan SH, did not show toxicity to activated sludge and it was biodegradable when it was at the concentrations tested. As far as acrylic syntans were concerned, the results indicated that the commercial anionic products (R83, B7815, ART-I and ART-II) were not so much inhibitory but were hardly biodegraded. However, a cationic product ART-III is potential to inhibit the activated sludge process in the effluent treating yard of tannery when it presented at high content. | |||
TO cite this article:Sun Danhong,Shi Bi. BIODEGRADABILITY EVALUATION OF TYPICAL LEATHER CHEMICALS (II)-THE BIODEGRADATION BEHAVIOURS OF ORGANIC TANNING AND RETANNING AGENTS ON ACTIVATED SLUDGE[OL].[13 January 2010] http://en.paper.edu.cn/en_releasepaper/content/38881 |
2. Biodegradability Evaluation of Typical Leather Chemicals (Iii)-The Biodegradation Behaviours of Vegetable Tannin Extracts | |||
He Qiang,Shi Bi | |||
Chemical Engineering 11 January 2010 | |||
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Abstract:The short- and long-term biodegradation behaviours of wattle, bayberry, valonia and chestnut tannin extracts, widely employed as vegetable tanning agents in leather industry, were studied in this paper. The results indicated that the four tannin extracts are biodegradable and should not show toxic effects on the respiration of activated sludge organisms. It is proved that the short-term biodegradabilities of the four tannin extracts are concentration dependent. Low concentration of the tannin extracts could be effectively biodegraded, but the biodegradation processes should be retarded when they present in wastewater at high concentrations, owing to the inhibitory effects of tannins on activated sludge process. In general, the short-term biodegradability of the four tannin extracts follows the sequence: valonia>chestnut>bayberry>wattle. The long-term biodegradation behaviours of the four tannin extracts showed that they could be thoroughly biodegraded with the prolongation of activated sludge process, even if they present in wastewater at high concentrations. It is therefore suggested that both the condensed tannin extracts (wattle and bayberry extracts) and the hydrolysable ones (valonia and chestnut extracts) are environmentally friendly leather chemicals, in consideration of their biodegradabilities. | |||
TO cite this article:He Qiang,Shi Bi. Biodegradability Evaluation of Typical Leather Chemicals (Iii)-The Biodegradation Behaviours of Vegetable Tannin Extracts[OL].[11 January 2010] http://en.paper.edu.cn/en_releasepaper/content/38771 |
3. EVALUATION OF ENVIRONMENTAL IMPACT OF TYPICAL LEATHER CHEMICALS. PART I:BIODEGRADABILITY OF FATLIQUORS UNDER ACTIVATED SLUDGE | |||
Sun Danhong,He Qiang,Zhang Wenjun,Liu Xin,Shi Bi | |||
Chemical Engineering 14 December 2007 | |||
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Abstract:Leather processing is associated with employment of many kinds of chemicals. These chemicals are usually used excessively in tanneries to ensure the quality of leathers. As a result, a part of the chemicals would inevitably remain in the tannery wastewater and form major pollutants of the leather industry. Biological treatment plays a significant role in removing these chemicals from wastewater and, in fact, biodegradability of these chemicals is directly related to their environmental friendliness. Recently, we have been undertaking a systematic evaluation of 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 sulfated castor, sulfated neat foot oil, sulfated fish oil, lecithin, chlorinated paraffin and alkyl sulfonyl chloride, were investigated. It has been found that four of them, sulfated castor, neat foot oil, fish oil and lecithin, can be effectively degraded by the activated sludge from the wastewater treating yard of tannery, which suggests that these four kinds of fatliquors are suitable to be used in leather making in consideration of their environmental friendliness. However, two other kinds of fatliquors, chlorinated paraffin and alkyl sulfonyl chloride, can not be degraded by activated sludge, and the presence of alkyl sulfonyl chloride in wastewater will lead to poisoning of activated sludge, which indicates that these two kinds of fatliquors should be limited in use. | |||
TO cite this article:Sun Danhong,He Qiang,Zhang Wenjun, et al. EVALUATION OF ENVIRONMENTAL IMPACT OF TYPICAL LEATHER CHEMICALS. PART I:BIODEGRADABILITY OF FATLIQUORS UNDER ACTIVATED SLUDGE[OL].[14 December 2007] http://en.paper.edu.cn/en_releasepaper/content/16961 |
4. EVALUATION OF ENVIRONMENTAL IMPACT OF TYPICAL LEATHER CHEMICALS. PART II:BIODEGRADABILITY OF ORGANIC TANNING AGENTS UNDER ACTIVATED SLUDGE | |||
Sun Danhong,He Qiang,Zhang Wenjun,Wang Yulu,Shi Bi | |||
Chemical Engineering 14 December 2007 | |||
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Abstract:The biodegradability of typical organic tanning agents, including aromatic syntans, aldehydic tanning agents and acrylic tanning agents, were investigated. The results showed that the biodegradation behaviors of these leather chemicals are closely associated with their chemical structures, molecular weights and compositions. Therefore, different organic tanning agents might result in different environmental impacts even though they belong to the same type of tanning agent. The four aromatic syntans tested in experiments exhibited low biodegradability in general. Among them, phenol-based syntan was not biodegradable and phenol-sulphone-based syntan produce a strong inhibitory effect on respiration of activated sludge. Comparatively, naphthalene-based syntan was somewhat easier to be biodegraded than other aromatic syntans. In the cases of aldehydic tanning agents, both formaldehyde and glutaraldehyde were not biodegradable and were toxic to organisms in activated sludge. Thus, they have potential hazardousness to inhibit biodegradation of other organic compounds in wastewater. However, an aliphatic aldehydic tanning agent tested in experiments was biodegradable and showed no toxicity to microorganisms in activated sludge. As for acrylic tanning agents, experimental results indicated that commercial anionic products have no negative effect on biodegradation activity of activated sludge but they themselves were hardly biodegraded. Whereas, cationic acrylic tanning agents have potential to inhibit activated sludge process when presented at a high concentration. | |||
TO cite this article:Sun Danhong,He Qiang,Zhang Wenjun, et al. EVALUATION OF ENVIRONMENTAL IMPACT OF TYPICAL LEATHER CHEMICALS. PART II:BIODEGRADABILITY OF ORGANIC TANNING AGENTS UNDER ACTIVATED SLUDGE[OL].[14 December 2007] http://en.paper.edu.cn/en_releasepaper/content/16928 |
5. EVALUATION OF ENVIRONMENTAL IMPACT OF TYPICAL LEATHER CHEMICALS. PART III:BIODEGRADABILITY OF VEGETABLE TANNIN EXTRACTS UNDER ACTIVATED SLUDGE | |||
He Qiang,Sun Danhong,Liu Xin,Lin Wei,Shi Bi | |||
Chemical Engineering 14 December 2007 | |||
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Abstract:The short-term (5d) and long-term (30d) biodegradation behaviours of black wattle, bayberry, valonia and chestnut tannin extracts were systematically investigated in this paper. The results indicated that all of these four vegetable tannin extracts are biodegradable although the biodegradation process might be retarded by them to some extent, owing to the inhibitory effect of tannins on the activated sludge process. Short-term biodegradabilities of the four tannin extracts were concentration-dependent. These tannin extracts could be effectively biodegraded in 5 days when their concentrations were 0.25g/L, but the biodegradation process was remarkably retarded when the concentrations of tannin extracts were increased to 5.00g/L. In general, short-term biodegradabilities of the four tannin extracts follow the sequence of valonia tannin>chestnut tannin>bayberry tannin>wattle tannin, implying that the hydrolysable tannins are easier to be biodegraded than the condensed tannins. The results of long-term biodegradation showed that all of the four vegetable tannin extracts can be completely biodegraded with the prolongation of the activated sludge process, even if they are presented in wastewater at high concentration. Therefore, the encouraging findings in this research suggest that vegetable tannin extracts are environmentally friendly leather chemicals in consideration of their biodegradability. | |||
TO cite this article:He Qiang,Sun Danhong,Liu Xin, et al. EVALUATION OF ENVIRONMENTAL IMPACT OF TYPICAL LEATHER CHEMICALS. PART III:BIODEGRADABILITY OF VEGETABLE TANNIN EXTRACTS UNDER ACTIVATED SLUDGE[OL].[14 December 2007] http://en.paper.edu.cn/en_releasepaper/content/16920 |
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