Preliminary observations on physical, chemical and zoological aspects in constructed wetlands in Thailand
1996
Thongchai Panswad | Orathai Chavalparit | Jirayu Phairin (Chulalongkorn Univ., Bangkok (Thailand). Faculty of Engineering. Dept. of Environmental Engineering)
Two constructed wetlands were evaluated on their performances under the tropical conditions. The first wetland was used to treat the domestic sewage from a governmental institute whereas the latter was used to improve the quality of the effluent from the central aerated lagoons, which received the wastewater already pretreated at about 100 factories in an industrial park compound. The hydraulic loading rate and the hydraulic retention time were 0.015 cubic m/square m d and 28 days as well as 0.3 cubic m/square m d and 3 days for the two wetlands, respectively. The physical, chemical and biological characteristics of the influent and quality of the effluent were monitored twice a week for two months. In the first wetland, the average effluent F-BOD (filtered BOD) was from 1 to 11 mg/l with the removal efficiency of 23 percent while the corresponding figures for F-TKN and F-TP were 2.3 mg/l and 0-80 percent as well as 0.6 mg/l and 36 percent, respectively. In the industrial-park wetland system, the removal efficiency for SS, copper, F-TKN and F-TP was 64.8, 54.4, 15.7 and 25 percent, respectively. From the study on the presence and population density of protozoa and metazoa, it was found that there was a high species diversity and the dominant group was the flagellated protozoa. Most abundant and frequent species were Bodo caudanus and Monas termo. The ciliated protozoa was apparently less abundant in the discovery from this study.
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