Using Copper Contaminated Plants Involved In Phytoremediation For Anaerobic Digestion

Anaerobic biogasification of heavy metal contaminated plants is a win-win way for resource utilization and pollution control in rural areas. Over the past 20 years, the domestic and foreign researches on heavy metal contaminated soil had been developed rapidly.Aiming at searching for a feasible disposal of remediation plants, this study investigated the anaerobic digestion capability of five plants and the effects of copper (Cu) and S,S’-ethylenediaminedisuccinic acid (EDDS, a chelator widely used in chelant-assisted phytoremediation) on biogas production to determine a feasible disposal method for plants used in remediation. Results suggest that the disposal of contaminated plants in biogas digestion offers great potential and may provide a possible solution for the resource utilization of plants used in remediation.Under the laboratory conditions of 35℃and total solids (TS) content of 20%, the different on anaerobic digestion gas production and methane production of five copper contaminated plants. The time of the total cumulative gas production in half were: Phytolacca americana L. (16d), Oenothera biennis L. (7d), Zea mays L. (14d), Brassica napus L, (16d), Elsholtzia splendens Nakai ex F. Maekawa(9d). In the first 30d, the Oenothera biennis L. cumulative gas production and methane production are greater than others, so it is a better copper contaminated plants for anaerobic digestion than other four plants, and it also has certain economic value.Brassica napus L. as the basic fermentation substrate, then added different concentrations CuSO4·5H2O, copper content of plant materials became 27.6,100,500, 1000,500 mg·kg-1 DW. Results showed that Compared to normal plants with low Cu content, the plants used in remediation with increased Cu levels (100 mg·kg-1) not only promoted anaerobic digestion and required a shorter anaerobic digestion time, but also increased the methane content in biogas. When the Cu content in plants increased to 500, 1000, and 5000 mg·kg-1, the cumulative biogas production decreased by 12.3%,14.6%, and 41.2%, respectively.With three kinds of sludge as the research object, compared the effects of anaerobic digestion biogas production。The inoculum was optimized by using different proportions of sludge. Results showed that the sludge from Sewage Treatment Plant was easier to be domesticated than others. In addition, different proportions of sludge had promoting effect on anaerobic digestion. Add 100 mg·kg-1 Cu during sludge domesticated would promote anaerobic digestion. Studies also found that EDDS restrained biogas production from anaerobic digestion.