COPPER REMOVAL BY BIOFILMS

Transcription

1 COPPER REMOVAL BY BIOFILMS 1 Kevin Brussee and 2 Xiaoqi (Jackie) Zhang 1 Masters Student 2 Assistant Professor Department of Civil and Environmental Engineering University of Massachusetts Lowell Lowell, MA 01854

2 Abstract A laboratory scale biofilm reactor will be used to develop biofilm growth on sampling slides by introducing a synthetic feed with a designed COD and copper concentration. The threshold of copper sorption will be determined by measuring the total copper and free copper in the influent, effluent, EPS and biofilms. The surface charge of the biofilm, and the amount of extracellular polysaccharides, extracellular proteins, and uronic acids within the biofilms will be determined to establish the cellular response to copper contamination for concentrations of 100ppb and 200ppb. The COD concentration of the synthetic feed will be adjusted for each of the two copper concentrations to determine the effect of substrate concentration on copper removal.

3 Background Copper is one of the most commonly used metals and one of the most widespread heavy metal contaminants of the environment. It is listed as one of the five pollutants of primary concern to Massachusetts MWRA s TRAC. However, some of Massachusetts' municipal/industrial wastewater treatment plants have difficulty meeting the copper discharge limit set by DEP/EPA, such as the Clinton WWTP.

4 Introduction It is believed that microorganisms can sorb positively charged heavy metals by producing negatively charged extracellular polymeric substances (EPS). EPS is comprised of extracellular proteins containing negatively charged amino acids and numerous polyanionic extracellular polysaccharides. A negative surface develops on the EPS, which subsequently provides metal binding sites. However, the presence of heavy metals may influence cellular production of EPS.

5 Objectives Determine the effectiveness of biofilms to remove copper from wastewater Determine the effects of copper on the production of EPS Determine the effects of substrate concentration on cellular response and copper removal

6 Significance This research attempts to provide information fundamental for proper understanding of cellular response to heavy metal contamination. The results can be used to improve the performance of fixed film systems and enhance the efficiency of heavy metal removal. This research will contribute to developing an effective treatment technology to remove copper and other heavy metals during wastewater treatment processes.

7 Experimental Flowchart Completely Mixed Rotating Liquor Inner Drum w/sampling slides Conc. Feed DI water Influent pump Effluent Hepa Filter Recycle line and pump Air Purifier Air Inlet

8 Air Purifier Reactor Controller Flow meter Influent pump Recycle pump Biofilm Reactor

9 Running Conditions of the Reactor Designed Influent COD 150 and 250 mg/l Designed Influent ph Approximately 7.5 Designed Influent Cu ug/l and 200 ug/l Targeted effluent COD 25 mg/l Targeted effluent ph 7.2 +/- 0.2 Targeted Reactor DO mg/l Influent flow 8.5 ml/min DI water/conc. Feed ratio 3.6:1 HRT 110 minutes Air flow ~ ml/min

10 Analyses Influent Parameters COD, ph, Total and Free Copper Total and Free Copper Biofilm Parameters TSS and VSS EPS Extraction Uronic Acid Surface Charge Extracellular Protein Effluent Parameters COD, ph, DO, Total and Free Copper Extracellular Polysacchrides

11 Anticipated Results Both a higher copper concentration and substrate COD concentration trigger increased cellular production of extracellular polysaccharides and extracellular proteins, effectively raising the threshold of copper sorption.

12 References Bradford, M. M A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemistry 72: Filisetti-Cozzi, T.M.C.C., N.C., Carpita Measurement of Uronic Acids without Interference from Neutral Sugars. Analytical Biochemistry 197: Gerhardt, P., Murray, R. G. E., Wood, A., Krieg, N. R Methods for General and Molecular Biotechnology. 11, Morgan, J. W., Forster, C. F., Evison, L A comparative study of the nature of biopolymers extracted from anaerobic and activated sludges. Water Research 24: Zhang, X., Bishop, P. L., Kinkle, B. K Comparison of extraction methods for quantifying extracellular polymers in biofilms. Water Science Technology 39:

13 Acknowledgments This project is funded by Massachusetts Water Resources Research Center.