Simultaneous hydrogen production and pollutant removal from olive mill wastewaters using electrohydrolysis process

Management of olive mill wastewaters is one of the most challenging environmental issue in Mediterranean countries due to its high organic load, color, presence of phenolic compounds and need for high energy cost. Performance of electrohydrolysis (EH) process in terms of removal of organic compounds, detoxification and discoloration of olive mill wastewater (OMW) with simultaneous energy production in the hydrogen gas form has been investigated using aluminum electrodes. Different reaction times and electric potential gradients have been tested in order to determine the most effective conditions for removal of pollutants. The optimum reaction time and current were determined as 8 h and 8 V, respectively. Under these conditions, removal efficiencies for tCOD, suspended solids, color and phenol were obtained as 73%, 84%, 91% and 75%, respectively. At the end of the operating period of 8 h, 1037 ml hydrogen gas was obtained. The results show that electrohydrolysis process can be used as an alternative solution for the management of OMW and the process can be upgraded with a better reactor design or combined with different treatment processes to achieve a better effluent quality to meet discharge standards.

Hydrogen production from municipal wastewaters via electrohydrolysis process

Nowadays, studies investigating alternative treatment processes for domestic wastewater have gained momentum. Rather than using conventional treatment plants which require energy and high amount of chemicals in order to treat the wastewaters, it is a viable option to use effective methods and to get clean energy in the form of hydrogen with alternative methods. Therefore, the aim of this study is to investigate the effect of electrohydrolysis process on domestic wastewater treatability at different DC voltages (4, 6, 8 and 10 V). Maximum hydrogen production was obtained from 8 V DC for 4 h reaction time. Under optimum conditions (8 V DC and 4 h operation time), 82% turbidity, 75% color, 86% TSS, 84% COD, 82% sCOD, 75% BOD, 38% oil and 40% total coliform removal efficiencies were achieved, respectively. It is a huge advantage to use this method which meets effluent discharge standards in such a short time without biological sludge production requiring additional operating cost. It has been shown that with the electrohydrolysis method, sustainable clean energy production and simultaneous pollution reduction can be achieved for domestic wastewater.

Electrohydrolysis pretreatment for enhanced methane production from lignocellulose waste pulp and paper mill sludge and its kinetics

A novel electrohydrolysis pretreatment enhances methane production from lignocellulose material during anaerobic digestion. A biochemical methane potential assay was carried out to determine the effect of direct current and the efficacy of electrohydrolysis pretreatment on biogas production. Methane yield was increased by 13.8%, to 301 ± 3 mL CH₄/g VS, when lignocellulosic waste was pretreated with electrohydrolysis. A net energy gain of 13,224 kJ was realized after electrohydrolysis pretreatment, which was 1.51 times higher than reported for thermal pretreatment. In addition, two kinetic models were used, including the modified Gompertz model to reproduce the experimental data. These finding support the potential for increased methane recovery from lignocellulosic waste using electrohydrolysis as a pretreatment.

Prerequisite - An electrohydrolysis pretreatment for anaerobic digestion of lignocellulose waste material

This novel work is focused on evaluating the electrohydrolysis pretreatment conditions (applied voltage and time) and anaerobic digestion process for the biological bioconversion of pulp and paper mill sludge into biogas in batch assay. The pretreatment at 15V for 45min shows highest impact on sludge solubilization. The XRD and FT-IR spectroscopic characterization shows the development of aliphatic, unsaturated and carbonyl carbon functionalities in the pretreated samples. FESEM picture also qualities the change in alteration of structure after pretreatment. Batch anaerobic bioreactor was carried out to determine the efficacy of electrohydrolysis pretreated and untreated pulp and paper mill sludge. The methane production potential was increased from 274±5 to 301±4mL CH₄/g VS after electrohydrolysis pretreatment.