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Remediation pilot study of the contaminated sediments in Er-Ren River

River sediments play an imperative role in ecosystems, such as self-cleaning capacity, planktonic habitat, and benthic organismal habitat. Once contaminated, the contaminant may enter human body or other organisms through food chains resulting adverse health effects and detriment of ecosystems. Taking Er-Ren River as an example, the major pollution source is the upstream pig farm discharges. Its downstream merges with Shan-Ye-Gung River and then flows into the sea. This area was famous for it metal recovery using open burning. Both particulate matters deposition and acidic drainage from metal recovery caused severe contamination of this river. According to the literature, among all contaminants, dioxins, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and heavy metals received most attentions. Historical data showed (1) dioxins are well below the regulated standards; (2) PCBs are well above the regulated standard; and (3) arsenic and chromium are near to the regulated standards. However, cost-effective remediation technology for this intermixed contamination does not exist. Here, we propose a new remediation technology by integrating biological and physicochemical processes with novel nanomaterials. The special feature of this technology is to assess the success of remediation not only on the removal of target contaminants but also on the water body toxicity after intervention. This approach will assure no accumulation of more toxic substances and true reduction of environmental risks. This pilot study will develop an integrated remediation technology. The study will have four different experiments in parallel, i.e. natural attenuation, biostimulation and bioaugmentation, physiciolchemical adsorption, and integrated remedaition. The results will be evaluated considering the removal or degradation of these three groups of contaminants, i.e., PAHs, PCBs, and heavy metals, in order to avoid to the situation of the decrease of certain contaminants causing the increase of other contaminants. We will employ a self-designed pilot-sutdy structure anchored on the river bed to conduct the four different experiments. The natural attenuation one will have no engineering intervention and all contaminant concentrations will be monitored. Biostimulation and bioaugmentation experiment will focus on biostimulation for the first year study. Food-grade soybean oil nanoemulsion and necessary nutrients will be added into the sediment to stimulate the microorganism growth to degrade the contaminants. Adsorption experiment will employ the in-house synthesized magnetite nanoparticles for recovery of heavy metals. The integrated remeditiaon will conmbine the nanoemsulsion and magnetite nanoparticles approaches. It is expected htat this study will not only improve our understanding in the technical problems in in situ remdiation and possible engineering solutions but also develop cost-effective remediation technologies. We belive this studu will promote Taiwan’s technology levels in sediments remediation , benefit the the river sediment quality and protect our citezens’ health.
Sediment;Polychlorinated biphenyls;Heavy metals