title: Anaerobic baffled reactor coupled with chemical precipitation for treatment and toxicity reduction of industrial wastewater.
abstract: This study describes the reduction of soluble chemical oxygen demand (CODs) and the removal of dissolved organic carbon (DOC), formaldehyde (FA) and nitrogen from highly polluted wastewater generated during cleaning procedures in wood floor manufacturing using a laboratory-scale biological anaerobic baffled reactor followed by chemical precipitation using MgCI2 .6H20 + Na2HPO4. By increasing the hydraulic retention time from 2.5 to 3.7 and 5 days, the reduction rates of FA, DOC and CODs of nearly 100%, 90% and 83%, respectively, were achieved. When the Mg:N:P molar ratio in the chemical treatment was changed from 1:1:1 to 1.3:1:1.3 at pH 8, the NH4+ removal rate increased from 80% to 98%. Biologically and chemically treated wastewater had no toxic effects on Vibrio fischeri and Artemia salina whereas chemically treated wastewater inhibited germination of Lactuca sativa owing to a high salt content. Regardless of the high conductivity of the treated wastewater, combined biological and chemical treatment was found to be effective for the removal of the organic load and nitrogen, and to be simple to operate and to maintain. A combined process such as that investigated could be useful for on-site treatment of low volumes of highly polluted wastewater generated by the wood floor and wood furniture industries, for which there is no suitable on-site treatment option available today.
authors.affiliation: Department of Biology and Environmental Science, Linnaeus University Kalmar, LNU, Sweden. sawanya.laohaprapanon@lnu.se
authors.forename: Sawanya
authors.initials: S
authors.lastname: Laohaprapanona
authors.affiliation: Department of Sanitary and Environmental Engineering, Rio de Janeiro State University - UERJ, Rio de Janeiro, Brazil.
authors.forename: Marcia
authors.initials: M
authors.lastname: Marquesa
authors.affiliation: Department of Biology and Environmental Science, Linnaeus University Kalmar, LNU, Sweden.
authors.forename: William
authors.initials: W
authors.lastname: Hogland
mesh_terms: D001421:Bacteria, Anaerobic / Q000187:drug effects* / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D002470:Cell Survival / Q000187:drug effects; D011232:Chemical Precipitation; D060389:Construction Industry / Q000295:instrumentation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007220:Industrial Waste / Q000517:prevention & control*; D010100:Oxygen / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000295:instrumentation*; D062065:Wastewater / Q000737:chemistry / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*; D018508:Water Purification / Q000295:instrumentation
chemical_list: D007220:Industrial Waste; D010100:Oxygen; D062065:Wastewater; D014874:Water Pollutants, Chemical