Improvement of biohydrogen production and treatment efficiency on palm oil mill effluent with nutrient supplementation at thermophilic condition using an anaerobic sequencing batch reactor

Thermophilic microflora was seeded into an anaerobic sequencing batch reactor for hydrogen production from palm oil mill effluent and supplemented with nitrogen, phosphorus and iron sources for biostimulants. The nutrient supplementation increased the hydrogen production yield from 1.6 ± 0.1 to 2.24 ± 0.03 mol H2 mol−1 hexose and hydrogen production rate from 4.4 ± 0.38 to 6.1 ± 0.03 l H2 l−1 POME d−1. Pollution reduction also increased as follows: COD removal from 35.5 ± 9.8 to 62.2 ± 2.8%, suspended solids removal from 91 ± 3.8 to 93.6 ± 1.1% and oil recovery from 75 ± 3 to 80 ± 1.5%, respectively. The nutrient supplementation strategy increased the bacterial diversity in the reactor and promoted in particular the growth of hydrogen-producing bacteria, e.g. Thermoanaerobacterium thermosaccharolyticum, as assessed by denaturing gradient gel electrophoresis.