Indian Journal of Geo Marine Sciences Vol. 47 (05), May 2018, pp. 1081-1087 Green and renewable electricity generation from wastewater inoculated with seaweeds extract using novel tool of bioreactors Abdul Majeed Khan* 1 , Shamsa Naz 1 , Muhammad Naeem Ahmed 2 & Kousar Yasmeen 1 1 Research Laboratory of Bioenergy (RLB), Department of Chemistry, Federal Urdu University of Arts, Science and Technology, Gulshan-e-Iqbal Campus, University Road, Karachi-75300, Pakistan 2 Department of Chemistry, The University of Azad Jammu and Kashmir, Muzaffarabad 13100, Pakistan *[E-mail: dr.abdulmajeedkhan@fuuast.edu.pk] Received 06 January 2017 ; revised 29 March 2017 This research article presents the production of biogas and conversion of biohydrogen to the electrical energy through the development of bioreactors using domestic wastewater supplemented with the extracts of seaweeds namely Melanothamnus afaqhusainii, Cystoseira indica and Sargassum tenerrimum as substrates. Biogas so produced by anaerobic digestion also contains biohydrogen which was converted to electricity by using bioreactors. Nickel coated zinc electrode was used to convert bio-H 2 to electricity through redox reactions. Power output was enhanced by the addition of the extracts of seaweeds and by introducing the air in to the cathodic chamber where oxygen reacted with the H + to form H 2 O. In addition, the maximum power output generated by series and parallel combinations of four units under the influence of air was found to be 7.70 mW (sufficient to turn on LED) and 3.83 mW respectively. Power output was found to be directly proportional to the total algal content, volume of biogas, COD, BOD and BOD 5 . [Keywords: Wastewater, Seaweeds, Biohydrogen, Electricity, Microbial fuel cell] Introduction Presently, waste to energy conversion is one of the environmental friendly and sustainable concepts to save our earth. There are a large number of biowastes around us which are the cheapest and easily available source for biogas production. Anaerobic digestion is a controlled biochemical process in which biodegradation of complex organic moieties takes place in the absence of air and converted to the end products of methane as major gas and other minor gases. Residue left after the anaerobic digestion of biomass can be used as a fertilizer 1 . The composition of biogas depends on biodegradable sources 2,3 . Biogas is produced from biomass like animal dung, poultry wastes, crop, plant wastes, energy crops, agricultural feed stock, vegetable wastes, waste paper, industrial wastes, sewage sludge, manures, garbage, algae etc. The wastewater contains a very complex mixture of compounds including organic matter, proteins, amino acids, carbohydrates, and lipids etc. that produce biogas upon anaerobic digestion 4 . Wastewater is a renewable and green source of biopower 5-9 . In this regard, microbial fuels cells of various designs have been developed by various researchers around the globe 10-12 . MFCs are the useful tool for the wastewater treatment and generate less sludge as compare to aerobic treatment 10,13 . MFCs can play a vital role as a novel tool for the generation of green and renewable alternative energy. They can simultaneously be used for wastewater treatment, electricity generation and biohydrogen production. Activated carbon is now commonly used in MFCs because it is cheap, easily available and its performance is very near to Pt catalyst which is highly costly and not affordable at commercial basis 12,14,15 . The dark fermentation process can be used for the production of bio-H 2 at relatively high rate 16,17 . However, in the present scenario, they have several limitations which need extensive basic research to optimize the power output for future commercial purpose. Macroalgae (seaweeds) and microalgae (single cell plants) are very useful for the production of biogas. A number of algae have already been studied for biogas production 18,19 . Melanothamnus afaqhusainii is a reddish brown marine alga belongs to Kingdom: Plantae; Phylum: Rohodophyta; Class: Florideophyceae and Family: Rohodomeleceae. Its first name was