Hydrogen production by immobilized cells—II. H 2-photoevolution and waste-water treatment by agar-entrapped cells of Rhodopseudomonas palustris and Rhodospirillum molischianum

Abstract

The photoproduction of molecular hydrogen by agar-entrapped cells of Rhodopseudomonas palustris and Rhodospirillum molischianum from sugar refinery wastes and straw paper mill effluents as electron donors has been investigated. On average, more than 30% of the initial chemical oxygen demand (COD) of the wastes was converted into H 2. Hence the process attains a partial reclamation of the effluents. Under the experimental conditions used, molecular hydrogen was produced for over a month at a rate ranging from 50 to 139 μl H 2 per mg cells dry wt per h depending on the organism and on the substrate. The amount of hydrogen evolved from 1l. of straw paper mill effluent surpassed 2l.