Effects of inoculum type and sizes in biofloc production / Tham Yim Hin

Faculty of Chemical and Process Engineering Technology

Final Year Report (Bachelor of Chemical Engineering ) -- Universiti Malaysia Pahang Al-Sultan Abdullah - 2024

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As a major contributor to both rural development and the provision of animal protein, the fisheries industry is vital to Malaysia's economy. Nitrogenous waste, however, poses problems for aquaculture and harms fish productivity and water quality. Using microorganisms to turn garbage into biomass, biofloc proves to be a sustainable alternative, cutting down on the demand for artificial feeds and freshwater. Cost-cutting measures within the fish farming sector might also be achieved using this method. To produce biofloc, this study investigated the effects of various inoculum sizes (0.05, 0.08, 0.1, 0.15, and 0.2 %(w/v)) and types (Bacillus subtilis used by Laziz Patin, Bacillus subtilis IS02, and Lactobacillus sp.) on the removal of nitrogen and biomass concentration. The inoculum was acclimatized at room temperature for 3 days. After inoculation and aeration for 3 days, 8 ppm of ammonium nitrate was added, and the mixture was fermented for an additional 2 days. Analyses of cell dry weight, optical density, ammonia, and nitrite removal were conducted on the first, third and fifth days of experiments. Results indicated that Bacillus subtilis (Laziz Patin) at 0.08 %(w/v), Bacillus subtilis IS02 at 0.15 %(w/v), and Lactobacillus sp. at 0.08 %(w/v) exhibit most effective ammonia removal. For nitrate removal, Bacillus subtilis (Laziz Patin) at 0.08 %(w/v), Bacillus subtilis IS02 at 0.1 %(w/v), and Lactobacillus sp. at 0.05 %(w/v) were identified as peak performers. In conclusion, both Bacillus subtilis and Lactobacillus sp. excelled in nitrogen removal during biofloc production, different inoculum types had different optimal inoculum sizes for nitrogen removal effects. This study suggested that Lactobacillus sp. at 0.08 %(w/v) is the effective choice from both technical and economic perspectives in biofloc production. Reading of basic colorimetric kit is lacks accuracy, for improvement, using a spectrophotometer was recommended and carbon must be sufficient to prevent bacteria from dying. Keywords: Biofloc; Bacillus subtilis; Lactobacillus sp.; Nitrogen Removal; Biomass Concentration.