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Fish Waste Management by Conversion Into Heterotrophic Bacteria Biomass

出版	Wageningen University, 2006
ISBN	90850441389789085044130
URL	http://books.google.com.hk/books?id=hvyiAAAACAAJ&hl=&source=gbs_api

註釋In chapter 7, the produced bacteria biomass was fed to shrimps (Litopenaeus vannamei), In total three different diets were used in a variance of a T-maze test: a commercial shrimp feed, the bacteria biomass, which was produced in the suspended growth reactors on C supplemented fish waste under conditions, comparable to those reported in chapter 3, and slurry, which was anaerobicaliy produced in a denitrification reactor. If the bacteria products would be attractive as diet, the nutrient retention of the RAS would be improved, resulting in a system, combining fish, bacteria and shrimp. The diet preference was interpreted as an expression of diet attractiveness. As a first result, shrimp were moving from an equal distribution before feeding (+/-50%, -2min), towards the feeding places (>50%, 2, 5, and 10 minutes after feeding). It was, therefore, inferred, that all bacteria biomass and commercial feed combinations were basically attractive for the shrimp. This response was not instantaneous. After feeding (2min) more than 80% of the shrimp were present at the feeding places and showed a significant preference for the commercial feed compared to the aerobically produced bacteria slurry. For the other diet combinations no significant differences could be detected for 2min. For 5 and lOmin after feeding, shrimp behavior changed from the commercial feed to the aerobically and anaerobicaliy produced bacteria biomass segments. From this study it was conc!uded that although the commercial diet was preferred above the aerobic slurry, the bacteria slurries had also attracted the shrimps. There was no unambiguous conclusion to be made regarding the preference for aerobic or anaerobic produced slurry. In chapter 8, the design of a suspended bacteria growth reactor integrated in a lOOMT African catfish farm was determined. This study integrated results from the earlier chapters to calculate the bacteria kinetics (yield=0.537gVSS/gC; endogenous decay coefficienl=0.033h^'; maximum specific growth rate=0.217h^ ; half-velocity constant=0.025g/l; and maximum rate of substrate utilization-0.404gC/gVSS*h). As part of the study a model was developed and validated. This model was used to calculate the VSS production and nutrient conversion by heterotrophic bacteria conversion for a lOOMT African catfish farm. The VSS production was 187gVSSAcg feed and the inorganic nutrients (N and P) were removed with an efficiency of 85 and 95% for a C supplementation level of 3.5gC/l (455gC/kg feed). A reactor integrated in a lOOMT farming facility would have a volume of 11m, based on a minimum HRT of6h. The production and potential re-use of heterotrophic bacteria biomass is, therefore, a prospective tool to lower nutrient discharge and to increase nutrient retention and sustainability of RAS in the future.