Effect of heavy metals on sulfate reduction activity in bioprecipitation process

• Main Authors: Chia-Hung Yang, 楊佳紘
• Other Authors: Jih-Gaw Lin
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/cwbs2x

碩士 === 國立交通大學 === 環境工程系所 === 93 === Heavy metal contamination is a serious problem from various industries such as leather manufacturing industry, metallurgy industry, electroplating industry, integrated circuit industry and printed circuit board industry, etc. Printed circuit board industry wastewater is contaminated with five heavy metals such as copper, zinc, nickel, chromium and cadmium. Among these heavy metals contamination, copper, zinc and nickel are relatively higher concentration than cadmium and chromium. The sulfate-reducing bacteria (SRB) have bioremediation potential to precipitate toxic heavy metals from water and wastewater as highly insoluble metal sulfides. Therefore, the present investigations are to optimize the bio-precipitation of copper, zinc and nickel using sulfate-reducing bacteria by mixture design and examine the bacterial population using FISH, DGGE and PCR. The objective of this research consists of two parts. In the first part, the heavy metals such as copper, zinc and nickel will be taken to study the effect on SRB during bioprecipitation process using mixture design. In the second part, bacteria population will be examined thoroughly using molecular techniques such as FISH, DGGE and PCR. The results demonstrated that the sulfate reduction ratio was 37% in the absence of copper and nickel when the concentration of zinc was 180 mg/L. This finding concluded that the removal of zinc was significantly higher because of the higher sulfate-reduction activity than nickel and copper. The experiment results confirmed that the average removal of Zn2+ was 97% by sulfate reducing bacteria (SRB), and the maximum removal ratio was 100%. The contour plot also indicated that the toxic order of the three heavy metals were: Cu2+ > Ni2+ > Zn2+. By the experimental result of FISH, we can find that the ratio of EUB338/DAPI was about 80%. And the SRB/DAPI ratio was between 55% and 60%. From the calculation of DAPI, we can also find that the microorganism number of the reactor were 109 cells/mL. From the photograph of DGGE, we can also find that the bacterial population of control was almost constant during the period of reaction time. However in the experimental reactor, the bacterial population has altered at the 20 and 92 hour.