Studying the biochar modified by AgNO3 from coffee grounds to handle organic pollutants and microorganism in the seafood-processing wastewater

Abstract

The aim of this study is to use four types of biochar modified AgNO3 from coffee grounds including CF5 (600°C/1.5h), CF6 (600°C/3h), CF7 (700°C/1.5h), and CF8 (700°C/3h) for the treatment of organic contaminants and microorganism in the seafood-processing wastewater. The results showed that the materials had the porous structure and the diameter of the pores corresponded to the crystal plane. The carbon content in the four samples reached over 90%. In addition, four samples observed the presence of Ag with the weight percentage varying from 0.06 to 0.09%. The adsorption capacities for pollutants by the four materials at different times were different. After the adsorption time, the COD value was still from 1.6 to 5.2 times higher than the limited value of the Vietnamese Standard QCVN 11:2015/MONRE - National technical regulation on the effluent of aquatic products processing industry. The three remaining parameters: TSS, ammonium (NH4+), and microorganism met the standard limit value requirement of QCVN 11:2015. The TSS contents decreased with the lowest adsorption efficiency in CF5 sample (68.87%) and the highest value in CF8 sample (99.21%); NH4+ content decreased respectively from 385.14 mg/L to 19.97; 15.55; 21.5 and 19.16 mg/L (CF5-CF8) with the efficiency over 94% after 2h adsorption. The removal capacity of coliform in CF7 sample is the highest value of 640 MPN/100 mL with the efficiency of 98.61% while the lowest one obtained in CF5 sample with 4.300 MPN/100 mL and the efficiency of 90.65%.