Environmental Management Tool for Treatment of Wastewater and Re-use in Aquaculture and Agriculture: The use of Wetlands and other Bio-systems in Treatment of Wastewater & re-use/recycling

Abstract

STELLA II v9.1.4 Modelling Software (1985-2010) was used to develop a fish pond model which is a good environmental health management tool. The problem studied was to reduce environmental pollution and encourage efficient reuse of used resources. The methods used in the study were quantitative by grabbing the wastewater samples three times a week seasonally in one year and data for model calibration was collected daily for a period of three months. Temperature, pH, and DO were measured “in situ” using portable Multi-parameter, HACH Model SENSION 156 (2001). Org-N, TKN, NH3-N, NO3-N, N-Sediments, Chl”a”/N-Planktons, N-Fishes and F-Coliforms were measured in laboratories by standard methods of water and wastewater treatment. The results obtained indicated that Ammonia-Nitrogen (NH3-N) in fish pond receiving outlet from Horizontal Subsurface Flow Constructed Wetland (HSSFCW) reached an average of 3.3 mg/l NH3-N more than 1.2 mg/l standard for re-use in agriculture and body threshold of 0.1 mg/l. N-Fishes was 21.1% higher than the Standards of 4-10% in animal tissues. The dominant routes of Nitrogen removal were sedimentation, accretion, decaying and denitrification resulting in 87.48% total N-removal at 95% confidence level. Sensitivity analysis of fish pond model gave the uptake rate of 0.3 d-1 NH4-N (R2 = 0.71) and fish growth rate of 7.0 d-1 (R2 = 0.99) as the most important parameters. It is concluded to construct two further HSSFCWs to buffer N-nutrients. It is recommended to conduct another research to examine Nitrogen and toxic heavy metals in soils and yields from farms to safeguard human health and the environment.