A critical review on graphene oxide membrane for industrial wastewater treatment.

An important way to promote the environmental industry's goal of carbon reduction is to promote the recycling of resources. Membrane separation technology has unique advantages in resource recovery and advanced treatment of industrial wastewater. However, the great promise of traditional organic membrane is hampered by challenges associated with organic solvent tolerance, lack of oxidation resistance, and serious membrane fouling control. Moreover, the high concentrations of organic matter and inorganic salts in the membrane filtration concentrate also hinder the wider application of the membrane separation technology. The emerging cost-effective graphene oxide (GO)-based membrane with excellent resistance to organic solvents and oxidants, more hydrophilicity, lower membrane fouling, better separation performance has been expected to contribute more in industrial wastewater treatment. Herein, we provide comprehensive insights into the preparation and characteristic of GO membranes, as well as current research status and problems related to its future application in industrial wastewater treatment. Finally, concluding remarks and future perspectives have been deduced and recommended for the GO membrane separation technology application for industrial wastewater treatment, which leads to realizing sustainable wastewater recycling and a nearly "zero discharge" water treatment process.

[Performance of Treating Straw and Animal Manure Mixture by an Integrated Process of Thermo-alkali-bi-enzyme Hydrolysis-anaerobic Digestion and Conditions of High Methane Yield].

To obtain a high methane yield during the anaerobic digestion of a straw and animal manure mixture, an integrated process of thermo-alkali-bi-enzyme hydrolysis-anaerobic digestion was proposed. A mixture of corn straw and cattle manure was selected as the experimental object. A higher dissolution efficiency of cellulose, hemicellulose, and protein in the thermo-alkali pretreatment, dosages and hydrolysis times of cellulase and protease in the bi-enzyme hydrolysis, and the methane yield and biogas production cycle in the anaerobic digestion with mixed slurry and hydrolysates were investigated respectively. The results showed that the dissolution efficiency (%TS) of cellulose (24.84%), hemicellulose (12.24%), and protein (8.92%) reached their highest levels at 0.5% NaOH and 80℃ (compared with the control group). The bi-enzyme hydrolysis process and conditions were as follows:cellulase hydrolysis was 80 U·g-1 and 18 h, and protease hydrolysis was 20 U·g-1 and 4 h. The hydrolysis efficiency of cellulose and protein reached 74.08% and 74.01%, respectively. The sugars in the hydrolysate were increased by 12-32 times. During anaerobic digestion, the maximum yield of methane from hydrolysate after thermo-alkali-bi-enzyme hydrolysis was 750 mL·h-1, and the gas production cycle was 50 h. Compared with the mixture after the thermo-alkali pretreatment, the methane production efficiency of the mixed hydrolysate after thermo-alkali-bi-enzyme hydrolysis was increased by 14 times, and the gas production cycle was noticeably shortened by 17 d. The results indicated that the thermo-alkali and enzyme hydrolysis pretreatment could effectively accelerate the hydrolysis rate in the anaerobic digestion with the mixture. The results of this study provide a new reference for developing efficient technology of high-value energy utilization of agricultural waste.