The conversion of waste obtained from agricultural processes into biocompatible materials (biomaterials) used in medical surgery is a strategy that will add more value in waste utilization. This strategy has successfully turned the rather untransformed wastes into high value products. Eggshell is an agricultural waste largely considered as useless and is discarded mostly because it contributes to pollution. This waste has potential for producing hydroxyapatite, a major component found in bone and teeth. Hydroxyapatite is an excellent material used in bone repair and tissue regeneration. The use of eggshell to generate hydroxyapatite will reduce the pollution effect of the waste and the subsequent conversion of the waste into a highly valuable product. In this paper, we reviewed the utilization of this agricultural waste (eggshell) in producing hydroxyapatite. The process of transforming eggshell into hydroxyapatite and nanohydroxyapatite is an environmentally friendly process. Eggshell based hydroxyapatite and nanohydroxyapatite stand as good chance of reducing the cost of treatment in bone repair or replacement with little impact on the environment.
Wastewater is untreated water that has high amount of nutrients such as nitrate, phosphate, ammonium and chemical oxygen demand (COD). When it is discharged into watercourse, it affects human and aquatic biota. The application of photosynthetic bacteria is considered bio-friendly system than the conventional one. Hence, the present study investigates the effectiveness of robust strain of photosynthetic bacteria for nitrate removal under different concentrations of 85, 135, 190, 235 and 320 mg/L. Serial dilution techniques was used for the isolation of the bacteria. The results showed that three bacterial isolate were obtained and were both screened for nitrate reduction ability. The isolate was able to remove 91, 90, 71, 67 and 55% of nitrate at 85, 135, 190, 235 and 320 mg/L respectively. The bacteriochlorophyll of the isolate was detected at peak range between 689-710 nm. The morphological, physiological and biochemical characterization showed that the isolate was identified as Rhodopseudomonas sp. The nutrient removal yield of the nitrate under different concentrations was found to be at range of 0.01- 0.033 g-1 DCW g-1 NO3.- This study suggested that the strain could be used as an efficient bacterial candidate for the treatment of wastewater containing high amount of nitrate.
High amount of turbidity was identified as one of the important factor affecting the successful cultivation of microalgae in palm oil mill effluent (POME). In this study, Chlorella sorokiniana was cultivated in POME, under different dilutions of 80, 60, 40 and 20% (v/v) with distilled water. The aim of the study is to investigate the effect of POME turbidity and the dilutions on the specific growth rate of microalgae. The results found that, C. sorokiniana grew on both sterilized and unsterilized condition. The result of the batch experiment showed that, POME turbidity of 45 NTU produce the maximum specific growth rate by C. sorokiniana of 0.14 d-1, which correspond to biomass production of 4.06 g/L and 0.2 d-1, which correspond to biomass production of 5.94 g/L in sterilized and unsterilized POME respectively. The POME of high turbidity concentration of 98 NTU yield only 0.07 d-1 maximum specific growth rate of algae. Results of this study identified 80% dilution as the optimal medium that can enhance maximum biomass production in POME. This could be useful in reducing the cost of bioenergy generation
Sulfate-reducing bacteria are categories of bacteria and archaea that can obtain energy by oxidizing organic compounds or molecular hydrogen (H 2) while reducing sulfate (SO 4 2−) to hydrogen sulfide (H 2 S). By analysis, these organisms "respire" sulfate rather than oxygen, a form of anaerobic respiration, the oxidation of hydrogen by the primary genus of Sulfate Reducing Bacteria (Desulfovibrio, Desulfovibrio desulfuricans) is catalyzed by enzymes called Hydrogenases. Three basic types of hydrogenases have been widely isolated from the primary genus of sulfate-reducing bacteria Desulfobibrio which differ in their structural subunits, metal compositions, physico-chemical characteristics, amino acid sequences, immunological activities, structural gene configuration and their catalytic properties. Broadly, hydrogenases can be considered as 'iron containing hydrogenases and nickel-containing hydrogenases. The iron-sulfurcontaining hydrogenase enzyme contains two ferredoxin-type (4Fe-4S) clusters and typical iron-sulfur center believed to be involved in the activation of H 2 yet it is the most sensitive domain to CO and NO 2 − .eventhough it is not featured in all species of genus Desulfovibrio. The nickel-(iron-sulfur)-containing hydrogenases, [NiFe] hydrogenase posses two 4Fe-4S centers and one 3Fe-xS cluster in addition to nickel and have been found in all species of Desulfovibrio with strong resistance to CO and NO 2 so far investigated. The genes encoding the large and small subunits of a periplasmic and membrane-bound species of the [NiFe] hydrogenase have been cloned in Escherichia coli and sequenced, however the functional complexity of the hydrogenase system remained unexplored as a result of the metabolic diversity in Desulfovibrio spp. The [NiFe] hydrogenase plays an important role in the energy metabolism of Desulfovibrio spp. Thus, the expression of the encoded structural genes would be an excellent marker for the metabolic functionalities under specific inducible environment.
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