title: Design and performance of hybrid constructed wetland systems for high-content wastewater treatment in the cold climate of Hokkaido, northern Japan.
abstract: The performance of six multistage hybrid constructed wetland systems was evaluated. The systems were designed to treat four kinds of high-content wastewater: dairy wastewater (three systems, average inflow content 2,400-5,000 mg·COD l(-1), 3-6 years of operation); pig farm wastewater, including liquid food washing wastewater (one system, 9,500 mg·COD l(-1), 3 years); potato starch processing wastewater (one system, 20,000-60,000 mg·COD l(-1), 3 years); and wastewater containing pig farm swine urine (one system, 6,600 mg·COD l(-1), 2.8 years) (COD = chemical oxygen demand). The systems contained three or four vertical (V) flow beds with self-priming siphons and surface partitions and no or one horizontal (H) flow bed (three to five beds). In some V flow beds, treated effluents were recirculated (Vr) through the inlet to improve performance. Mean annual temperature was 5-8 °C at all locations. To overcome clogging due to the high load in a cold climate, we applied a safety bypass structure and floating cover material to the V flow beds. Calculated average oxygen transfer rates (OTRs) increased proportionally with the influent load, and the OTR value was Vr > V> H. The relations of load-OTR, COD-ammonium, and a Arrhenius temperature-dependent equation enable the basic design of a reed bed system.
authors.affiliation: NARO Tohoku Agricultural Research Center, Akahira-4, Shimo-Kuriyagawa, Morioka, Iwate, 020-0198, Japan E-mail: katokuni@affrc.go.jp.
authors.forename: K
authors.initials: K
authors.lastname: Kato
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: H
authors.initials: H
authors.lastname: Ietsugu
authors.forename: H
authors.initials: H
authors.lastname: Sasaki
authors.forename: J
authors.initials: J
authors.lastname: Harada
authors.forename: K
authors.initials: K
authors.lastname: Kitagawa
authors.forename: P K
authors.initials: PK
authors.lastname: Sharma
mesh_terms: D064751:Ammonium Compounds; D000818:Animals; D002417:Cattle; D003081:Cold Climate; D005511:Food Handling; D007220:Industrial Waste; D007564:Japan; D009584:Nitrogen; D013552:Swine; D014865:Waste Disposal, Fluid / Q000379:methods*; D053833:Wetlands
chemical_list: D064751:Ammonium Compounds; D007220:Industrial Waste; D009584:Nitrogen