Effects of Alginate and Chitosan on Activated Carbon as Immobilisation Beads in Biohydrogen Production

Advanced strategies for enhancing dark fermentative biohydrogen production from biowaste towards sustainable environment

As a clean energy carrier, hydrogen is a promising alternative to fossil fuel so as the global growing energy demand can be met. Currently, producing hydrogen from biowastes through fermentation has attracted much attention due to its multiple advantages of biowastes management and valuable energy generation. Nevertheless, conventional dark fermentation (DF) processes are still hindered by the low biohydrogen yields and challenges of biohydrogen purification, which limit their commercialization. In recent years, researchers have focused on various advanced strategies for enhancing biohydrogen yields, such as screening of super hydrogen-producing bacteria, genetic engineering, cell immobilization, nanomaterials utilization, bioreactors modification, and combination of different processes. This paper critically reviews by discussing the above stated technologies employed in DF, respectively, to improve biohydrogen generation and stating challenges and future perspectives on biowaste-based biohydrogen production.

Techno-Economic Assessment of On-Farm Anaerobic Digestion System Using Attached-Biofilm Reactor in the Dairy Industry

In this study, a techno-economic assessment of an on-farm biogas system using an anaerobic biofilm reactor utilizing cow manure as a fermentation substrate was evaluated. A projection model was developed using Microsoft Excel software with three outputs, the size and dimension of a bioreactor, experimental microbial kinetic studies, and the economic studies based on the experimental results. Characterization analysis of cow manure wastewater showed the total solid (TS), total volatile solid (TVS), total carbohydrate (TC), chemical oxygen demand (COD), and pH values which were 10.95 g/L, 8.65 g/L, 6.65 g/L, 57.80 g/L, and 7, respectively. Using the modified Gompertz equation for the microbial studies, it was found that, at 37 °C and 20 days hydraulic retention time (HRT), the biogas yield was 934.54 mL/gVS, the volume of biogas produced was 11.28 m3/d, and 22.56 kWh of electricity was generated. The Gompertz prediction helps to determine the optimal HRT for the system so that the microorganisms are at their optimum stage to produce biogas. The economic analysis was done, and the results illustrated that, when the rate of cow manure produced was at 55 L/day.cow, the net present value (NPV) was RM 611,936.09, with a 13% internal rate of return (IRR), 0.14 return on investment (ROI), and 7.02 years of payback period (PP). By developing a techno-economic assessment that included all the necessary parameters such as sizing of the bioreactor, microbial kinetic studies, and economics of the plant, farmers could easily implement the system into their farms. This model showed that the anaerobic digestion system utilizing an attached biofilm with cow manure as a fermentation inoculum and substrate was applicable on an industrial scale to generate electricity and reutilize to the farm, at the same time generating additional income from the production of fertilizer.

Carbonaceous Adsorbents Derived from Agricultural Sources for the Removal of Pramipexole Pharmaceutical Model Compound from Synthetic Aqueous Solutions

The aim of the present study was to synthesize various samples of activated carbon (AC) from different agricultural sources as precursors, like orange peels, tea stalks, and kiwi peels, as well as sucrose. The synthesis of AC was achieved with chemical activation using H3PO4 and KOH. The produced AC samples were tested as adsorbents for the removal of a pharmaceutical model compound, pramipexole dihydrochloride (PRM), from synthetic aqueous synthetic solutions. The produced-from-sucrose AC presented the higher yield of synthesis (~58%). The physicochemical features of the materials were analyzed by FTIR spectroscopy, N2 physisorption, and SEM imaging. More specifically, the AC sample derived from sucrose (SG-AC) had the highest specific surface area (1977 m2/g) with the total pores volume, mesopores volume, and external surface area being 1.382 cm3/g, 0.819 cm3/g, and 751 m2/g, respectively. The effect of the initial pH and PRM concentration were studied, while the equilibrium results (isotherms) were fitted to Langmuir and Freundlich models. The maximum adsorption capacities were found to be 213, 190, 155, and 115 mg/g for AC samples produced from sucrose, kiwi peels, orange peels, and tea stalks, respectively.

Special Issue on “Biotechnology for Sustainability and Social Well Being”

Bioprocessing is a very important part of biotechnology that utilizes living organisms and their components to produce various types of products [...]