Tang S N, Fakhru'l-Razi A, Hassan M A, Karim M I
Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia.
Artif Cells Blood Substit Immobil Biotechnol. 1999 Sep-Nov;27(5-6):411-6. doi: 10.3109/10731199909117712.
Rubber latex effluent is a polluting source that has a high biochemical oxygen demand (BOD). It is estimated that about 100 million liters of effluent are discharged daily from rubber processing factories. Utilization of this effluent such as the use of a coupled system not only can reduce the cost of treatment but also yield a fermentation feedstock for the production of bioplastic. This study initially was carried out to increase the production of organic acids by anaerobic treatment of rubber latex effluent. It was found that through anaerobic treatment the concentration of organic acids did not increase. Consequently, separation of organic acids from rubber latex effluent by anion exchange resin was examined as a preliminary study of recovering acetic and propionic acids. However, the suspended solids (SS) content in the raw effluent was rather high which partially blocked the ion-exchange columns. Lime was used to remove the SS in the rubber latex effluent. After the lime precipitation process, organic acids were found to adsorb strongly onto the anion exchange resin. Less adsorption of organic acids onto the resin was observed before the lime precipitation. This was probably due to more sites being occupied by colloidal particles on the resin thus inhibiting the adsorption of organic acids. The initial concentration of organic acids in the raw effluent was 3.9 g/L. After ion exchange, the concentration of the organic acids increased to 27 g/L, which could be utilized for production of polyhydroxyalkanoates (PHA). For PHA accumulation stage, concentrated rubber latex effluent obtained from ion exchange resins and synthetic acetic acid were used as the carbon source. Quantitative analyses from fed batch culture via HPLC showed that the accumulation of PHA in Alcaligenes eutrophus was maximum with a concentration of 1.182 g/L when cultivated on synthetic acetic acid, corresponding to a yield of 87% based on its cell dry weight. The dry cell weight increased from 0.71 to 1.67 g/L. On the other hand, using concentrated rubber latex effluent containing acetic and propionic acids resulted in reduced PHA content by dry weight (14%) but the dry cell weight increased from 0.49 to 1.30 g/L. The results clearly indicated that the cells grow well in rubber latex effluent but no PHA was accumulated. This could be due to the high concentration of propionic acid in culture broth or other factors such as heavy metals. Thus further work is required before rubber latex effluent can be utilized as a substrate for PHA production industrially.
橡胶胶乳废水是一种具有高生化需氧量（BOD）的污染源。据估计，橡胶加工厂每天排放约1亿升废水。利用这种废水，例如使用耦合系统，不仅可以降低处理成本，还能产生用于生产生物塑料的发酵原料。本研究最初旨在通过厌氧处理橡胶胶乳废水来提高有机酸产量。结果发现，通过厌氧处理，有机酸浓度并未增加。因此，作为回收乙酸和丙酸的初步研究，考察了用阴离子交换树脂从橡胶胶乳废水中分离有机酸。然而，原废水中的悬浮固体（SS）含量相当高，部分堵塞了离子交换柱。使用石灰去除橡胶胶乳废水中的SS。石灰沉淀过程后，发现有机酸强烈吸附在阴离子交换树脂上。在石灰沉淀之前，观察到有机酸在树脂上的吸附较少。这可能是由于树脂上更多的位点被胶体颗粒占据，从而抑制了有机酸的吸附。原废水中有机酸的初始浓度为3.9 g/L。离子交换后，有机酸浓度增加到27 g/L，可用于生产聚羟基脂肪酸酯（PHA）。在PHA积累阶段，将从离子交换树脂获得的浓缩橡胶胶乳废水和合成乙酸用作碳源。通过HPLC对补料分批培养进行的定量分析表明，在合成乙酸上培养时，嗜碱产碱杆菌中PHA的积累量最大，浓度为1.182 g/L，基于其细胞干重的产率为87%。干细胞重量从0.71 g/L增加到1.67 g/L。另一方面，使用含有乙酸和丙酸的浓缩橡胶胶乳废水导致PHA干重含量降低（14%），但干细胞重量从0.49 g/L增加到1.30 g/L。结果清楚地表明，细胞在橡胶胶乳废水中生长良好，但没有积累PHA。这可能是由于培养液中丙酸浓度过高或其他因素，如重金属。因此，在橡胶胶乳废水能够作为PHA生产的工业底物之前，还需要进一步的研究。
