Nano‐layered TiO₂ for effective bacterial disintegration of waste activated sludge and biogas production

Abstract

BACKGROUND Proper management of the huge amount of waste activated sludge generated during the conventional treatment of wastewater is nowadays a major environmental issue. Proper treatment of sludge needs huge investment and proper handling. To address this issue, the immobilized photocatalyst (TiO2) mediated exocellular fractionation of bacterial pretreatment for anaerobic digestion was utilized as a sludge treatment technique. RESULT Ti was deposited on glass substrate by a DC spluttering technique, and a TiO2 layer was formed by annealing in oxygen atmosphere. This immobilized TiO2 efficiently extricated the extracellular components after 45 min by removing 99% of the total extractable extracellular polymeric substances. The exocellular fractionated bacterial pretreatment induced 20% of COD solubilization with methane generation of about 0.0217 g COD g‐1 COD d‐1, which was higher than the sludge without any treatment and sludge with bacterial pretreatment only. CONCLUSION An 8% increase in COD solubilization was achieved, which generated high quantities of methane. With the advantage of methane generation, the maximum profitable sludge reduction was obtained. Thin film deposition of TiO2 enables easy recovery of TiO2. The cost, energy, and solid balance analysis confirmed that this treatment method is field applicable. © 2018 Society of Chemical Industry

Synergistic Effects of Magnetic Nanomaterials on Post-Digestate for Biogas Production

“…Slow or low biogas production was observed during the first week, accompanied by rapid production from the 5th to the 25th day, followed by steady production until the last week when the system was shut down. The slow production observed is in agreement with other reported works which suggest the microbes need to get acclimatised before they begin production [4,5,12]. The overall biogas production was enhanced by the MNP additives to the bioreactors as compared to the control system without any MNP additives.…”

“…This is associated with the quality of the feedstock and the degree of degradation efficiency in the process, as well as the extent to which the post-treatment process was carried out. Significantly, sludge treatment contributes greatly to the total cost of wastewater treatment plants [4,5]. It was observed that the addition of MNPs to the bioreactors were easily separated from the sludge by an external magnet.…”

“…Recent complex sludge production from primary, secondary, and tertiary treatment in wastewater treatment plants (WWTPs) has resulted in pressing concerns, as its treatment cost accounts for 20-55% of the total operating costs of WWTPs. This necessitates the possibility of considering an abatement technology for sewage sludge treatment given such sensitive factors as the end product, energy generation, the environment and human health impacts [4,5]. Sewage waste is becoming a major concern in South Africa (SA), since the volume of solid waste produced is escalating daily.…”

Disintegration of Wastewater Activated Sludge (WAS) for Improved Biogas Production

“…Many oxidation techniques, including Fenton reactions [101]) and new reactions concerning peroxomonosulphate (PMS; [102]), nano-layered TiO 2 [103] and dimethyldioxirane (DMDO), can cause the alteration of refractory organic matter into easily accessible and soluble biochemical oxygen demand (BOD), and subsequently improve the biogas yield [88] (Table 2). Recently, a newly greener oxidant for this purpose, peracetic acid (PAA), has been proposed to improve anaerobic digestion [104].…”