Development of ideal filtration system for rooftop fish farming at urban households

Abstract

The experimental study was based on the establishment of suitable filtration system on the basis of comparative study of the effectiveness between the different filtration systems consisting coarse filter, coarse filter with plant and only plant in re-circulatory condition at rooftop. During the six months _ study period the experimental study of the filtration systems were done on the reduction rate of NH3, POs* and NHs* of water used for prawn (Macrobrachium rosenbergii) culture in twelve (12) plastic barrel (250L water holding capacity). Water samples were collected from each filtration system after the recirculation process. Dissolved oxygen, temperature and pH were monitored daily; ammonia, ammonium and phosphate concentration determined once in a week. The average amount of NH3, PO4* and NH4* of filtrated water was found (mean+SD) 0.15+0.01(mg/L), 0.16+0.02(mg/L) and 0.06+.03(mg/L) respectively in plant system; 0.17+0.02(mg/L), 0.42+0.01(mg/L) and 0.08+.01(mg/L) in coarse filter system and 0.13+0.02(mg/L), 0.31+0.01(mg/L) and 0.06+0.02(mg/L) in coarse filter with plant system. The level of NH3 in water of coarse filter with plant was significantly reduced into (0.20+0.02 (mg/L)) than only plant system (0.04+0.01 (mg/L)) and coarse filter system (0.01+0.02 (mg/L)) (p<0.05). Plant system shows significant reduction (p<0.05) of NH4* and PO4* (0.39+0.02 (mg/L) and 0.09+0.03(mg/L)) than coarse filter (0.03+0.01(mg/L) and 0.19+0.01 (mg/L)). Coarse filter with plant also reduced more PO4* (0.25+ 0.01(mg/L)) than coarse filter system (0.19+0.01 (mg/L)).The average water temperature, pH and DO of the filtrated water were 27.6°C, 7.4 and 4.03mg/L respectively. At the initial stage of the study period prawn was stocked 55pL/tank where average length was 0.2mm. At the end of the study period final length estimated 5.5cm and the weight 2.85g on average. The results of this study showed the possibility of establishment of a suitable filtration system for rooftop fish culture.