Nickel spiking to improve the methane yield of sewage sludge

Abstract

The presence of micro-nutrients can be stimulatory for the anaerobic digestion (AD) of hardly degradable wastes and thus, improve process performance. Among the essential trace elements, nickel is involved in multiple important enzymes necessary for efficient AD. The present study investigates the effect of nickel spiked sewage sludge on batch and continuous mode operation. Metal spiking was conducted in the form of nanoparticles (Ni-NPs) and salt (NiCl2•6H2O). Results from batch assays showed that 5 mgNi-Salt/kgVS in the presence of Nitrilotriacetic acid (NTA) enhanced the methane yield by ∼10% compared to the untreated sample. The impact of Ni-NPs in the AD process was also positive, but slightly lower compared to the effect of NiCl2•6H2O. The stimulatory impact of Ni was also revealed in continuously fed digester boosting the methane yield by ∼8%. Overall, the improved methane production indicated that methanogenic archaea were favoured by the simultaneous supplementation of Ni and NTA.

Application of nano-structured materials in anaerobic digestion: Current status and perspectives

“…The undesired effect of 2 mg/L Co NPs on biogas and methane production are in agreement with those reported by Facchin et al (2013) declaring that the supplementation of excess metals could have a negative effect on acetoclastic methanogenesis or on other metabolic pathways of an AD process. Tsapekos et al (2018a) investigated the effect of Ni NPs (<100 nm) on anaerobic digestion of sewage sludge in batch and continuous mode at thermophilic condition.…”

Recent Advances and Perspectives of Nanotechnology in Anaerobic Digestion: A New Paradigm towards Sludge Biodegradability

“…On addition of Ni nanoparticle to the cattle dung digestion, 70.46% increased methane output was achieved with a 90.47% decrement in hydrogen sulfide gas. In addition, 19.2% and 12.1% of total suspended solid (TSS) and volatile suspended solids (VSS) removal was obtained at pH Level of 6.8-7.3 with 1.88-fold increment in the hydrolysis rate constant [18]. Ni nanometal of concentrations ranging from 0.5 to 2 mg/L enhanced the AD of dairy manure by 55-101%.…”

“…The economic feasibility of using nanomaterial for biogas production mainly relies on the amount of biogas energy produced and revenue generated along with the cost of NPs utilized in the digestion process [80]. Energy and cost-benefit analysis was performed by Abdelwahab et al [18] to study the effect of usage of various NPs (Ni, Fe and Fe 3 O 4 ) in AD. It was found that among the three NPs, Fe showed higher energy content of 403 kWh with a net profit of USD −676.5, whereas low net-energy (192.6 kWh) and net profit (7.2 USD) were achieved during the usage of 5 mg/L of Fe NP.…”

Utilization of nanoparticles for biogas production focusing on process stability and effluent quality

“…These findings showed that all treated bio-digesters' H 2 S production were successfully reduced by Ni NPs. The precipitation of metal sulfides, such as nickel sulfide (NiS) [78,127,128], may have reduced the amount of H 2 S yield.…”

“…With a focus on the impact of Ni NPs on the stability of the anaerobic digestion process, Tsapekos et al [78] investigated the effects of Ni NPs on pH, TA, and VFAs during the anaerobic digestion of sewage sludge at two concentrations (5 and 10 mg/Kg VS). To begin with, neither the pH nor the TA values of the treatment significantly deviated from those of the control.…”