Evaluations of Multi-Component Biosorption of Heavy Metals by Pseudomonas aeruginosa PU21 with Batch and Continuous Hollow Fiber Microfiltration Systems

• Main Authors: Chen, Chia Chi, 陳嘉祺
• Other Authors: Chang Jo-Shu
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/22175829914128265535

碩士 === 逢甲大學 === 化學工程研究所 === 85 === Our previousestudies demonstrated that mercury-resistant strain Pseudomonas aeruginosa PU21 (Rip64) is capable of effectively adsorbing a variety of heavy metals including Hg, Pb, Cu, and Cd. At pH 5, saturation biosorption capacity of biomass of P. aeruginosa PU21 (Rip64) for Pb, Cu, and Cd was 520, 632, and 327 mmol/g dry cell, respectively. In order to evaluate the feasibility of utilizing the biomass as a practical heavy-metal biosorbent, it is of importance to further reveal the biosorption behavior of the biomass under the multi-metal- component environment, as often occurred in the industrial effluents. This study started from batch-mode operations to investigate the competitive biosorption and ion exchange behaviors when two or three of Pb, Cu, and Cd ions were simultaneously present. The research then switched to the design of continuous biosorption processes, which applied hollow-fiber membrane reactors for the regeneration of the biomass, as well as for the recovery of the trapped metal ions. The batch biosorption results showed that metal adsorption capacity of the biomass decreased in the order of Cu > Pb > Cd. Evidence also showed that the adsorption sites of Pb and Cd were probably included in Cu biding sites, whereas Pb and Cd adsorption sites may be partially overlapped. When Pb, Cu, and Cd co-existed, the biomass exhibited the highest affinity to Pb, while adsorption of Cd was the least favorable. The ability to replace adsorbed metal ions from the cell surface was in the order of Pb > Cu > Cd. It is thus not surprising to observe the highest initial adsorption rate for Pb, followed by Cu, and then Cd. The results obtained from continuous hollow fiber systems showed that the removal efficiency was clearly Pb > Cu > Cd, which appeared to be consistent with batch biosorption results. In the hollow-fiber processes, the efficiency of Cu and Cd removal can be appreciably enhanced with a multi-column operation, and different adsorbed metal ions may be recovered individually with appropriate operation strategies. This study also made an attempt to modify traditional Langmuir isotherm to describe the experimental data resulted from multi-component adsorption. It is found that Model II and Model III exhibited better description of the experimental results than the original Langmuir model did. The dynamic adsorption models (Model A and B) were also developed for continuous hollow-fiber biosorption processes. Model A showed excellent predictions for the results of single-metal processes. However, the derivation of Model A may become extremely complex, and required tedious numerical manipulations, when it was arranged to describe multi-component systems. In contrast, Model B introduced the concept of mass transfer to simplify the trouble-causing dq/dt term in Model A, and thus can be easily utilized to predict the results from continuous multi-metal biosorption processes.