Biological treatment of organic waste polluting the environment and bio-hydrogen production

Abstract

Thirty four local isolates of bio-hydrogen producing anaerobic bacteria were isolated from samples of solid waste of sewage plants from different regions using liquid and solid mineral salt medium at initial pH of 7 and incubated at 37 ºC for 72 hr. .The ability of isolates was tested to produce bio-hydrogen, using liquid production medium. Results indicate that the bio-hydrogen production in 25 isolates cannot be detected, while 9 isolates showed the ability to produce bio-hydrogen and that theAn-18 isolate showed the highest level of bio-hydrogen production(34 ppm) after 72 hr. of incubation at 37 ºC. Anaerobic isolates producing bio-hydrogen were identified based on morphological characteristics and some biochemical tests, results showed that 7isolates belong to the genus Actinomycessp.and only two isolates belong to the genus Clostridium sp., Then prepared the mixed culture from 7 isolates and subsequently was used as inoculums for hydrogen production medium. Inoculated the bioreactor containing the residues of agricultural and household by mixed culture (1 ml/ 50 ml medium) at initial pH of 7 and incubated at 37 ºC by using water bath for 20 days ,and subsequently was estimated the amount of hydrogen produced in every day. The results showed that hydrogen production was started from the second day (12 ppm) andreached its maximum production for the period from 14-17 days after the start of the experiment.