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The current study focusses in evaluating the mechanical properties (yield strength, ultimate tensile strength and elongation %) and microstructures of as printed and heat treated tensile samples produced by Selective Laser Melting (SLM) which is an Additive Manufacturing (AM) technique. The as printed IN625 alloy exhibited good mechanical properties as compared to cast and wrought alloy, owing to fast cooling rates that give very fine dendritic/cellular structures during the SLM process. Standard solutionizing and precipitation hardening treatment was given to the SLM as printed samples. The as printed sample’s ductility increased from 30% elongation to 47% elongation with small drop in tensile strength from 878MPa to 836MPa. The increase of ductility after heat treatment was evident in the change of fracture morphology from long straight striations with dimple shape ductile like features in the as printed sample to mainly dimple shaped ductile-like fracture surface in the heat treated sample as observed in the FESEM.

Harvesting of microalgae is one of the main challenges in the production of biodiesel due to the small cell size of microalgae cells. Chemical flocculants have been generally used in the harvesting of microalgae, but they are harmful to the environment and relatively costly. Therefore, the utilization of waste biomass in producing bioflocculants is the current research niche to introduce environmental-friendly harvesting method and to minimize the cost of biodiesel production. Thus, in the current work, flocculation Chlorella vulgaris using mild acid-extracted bioflocculants from miscellaneous waste biomass (cockle shell, peanut shell and banana peel) were conducted by varying the pH values, the dosage of bioflocculants and temperatures. Cockle shell bioflocculant demonstrated the best flocculation performance, with highest flocculation efficiency of 85.2% compared to the peanut shell bioflocculant with flocculation efficiency of 37% and banana peel bioflocculant with flocculation efficiency of 16.3%. The optimum flocculation conditions for cockle shell bioflocculant were determined as follow: pH 9, bioflocculant dosage of 140mg/L and temperature of 30oC. The findings herein presented practical applicability of bioflocculants extracted from cockle shell for safe, rapid and inexpensive microalgae harvesting.

This study was conducted to evaluate the COD removal efficiency of Photo-Fenton oxidation process. The reagents used in the Photo-Fenton process are catalyst Fe2+ and H2O2 as oxidizing agent. A 16W UV lamp was used to carry out the experiments. All the experiments were performed in batch mode to investigate the influence of operating conditions viz., Fenton reagents dosage, molar ratio and reaction time. The maximum COD removal observed was 68% under optimum operating conditions. The operating conditions H2O2/Fe2+ molar ratio = 3 and reaction time = 90 minutes were found to optimum. The dosages of Fenton reagents i.e. hydrogen peroxide and Fe2+ were optimum at 0.09 mol/L and 0.03 mol/L respectively.

Natural source of coagulant is certainly being considered in addressing the disadvantages associated with the use of inorganic coagulants. Annona muricata is hypothesized to be new material as natural coagulant aid in coagulation-flocculation process. On the other hand, due to the high lipids content in microalgae, namely, Chlorella vulgaris is used in producing renewable energy, i.e. biodiesel. Coagulation-flocculation is an effective method in microalgae harvesting. Thus, in this study, a novel natural coagulant aid extracted from fruit waste in algae harvesting. It is aimed to (1) to extract natural coagulant aid (hereafter is known as biopolymer) extracted from Annona muricata seeds in algae harvesting, and (2) to evaluate the operational conditions of coagulation-flocculation process by utilizing the biopolymer. As a result, it is observed that acid extraction and extraction through sodium chloride does not show any yield. On the other hand, the harvesting efficiency showed positive response as coagulant aid at 20 mg/L.

The efficiency of Fenton’s oxidation was assessed in this study for hazardous waste landfill leachate treatment. The two major reagents, which are generally employed in Fenton’s process are H2O2 as oxidizing agent and Fe2+ as catalyst. Batch experiments were conducted to determine the effect of experimental conditions viz., reaction time, molar ratio, and Fenton reagent dosages, which are significant parameters that influence the degradation efficiencies of Fenton process were examined. It was found that under the favorable experimental conditions, maximum COD removal was 56.49%. The optimum experimental conditions were pH=3, H2O2/Fe2+ molar ratio = 3 and reaction time = 150 minutes. The optimal amount of hydrogen peroxide and iron were 0.12 mol/L and 0.04 mol/L respectively. High dosages of H2O2 and iron resulted in scavenging effects on OH• radicals and lowered degradation efficiency of organic compounds in the hazardous waste landfill leachate.