Preparation And Application Of Paper Mill Sludge-based Granular Activated Carbon Fillers For Fluidized-bed Bioreactor

Paper mill sludge (PMS) was utilized to prepare granular activated carbon (GAC) fillers for fluidized-bed bioreactor (FBBR) through stream activation in this study. The effect of production process conditions (carbonization temperature, carbonization time, activation temperature, activation time) on the properties of the PMS was investigated to select the optimum production process conditions. Then, properties improvement of PMS-based GAC for fluidized-bed bioreactor (FBBR) was investigated by Bentonite (Na) powders blending and acid washing treatments. The GAC fillers were used in FBBR to investigate the capacity of wastewater treatment. The main conclusions are as follows:(1) The component and DSC-TG analysis of the sludge showed that the propration of PMS-based GAC was practicable. The optimal conditions which determined by ash, volatile matter and fixed carbon were:carbonization temperature of450℃, carbonization time of50min, activation temperature of800℃and activation time of60min. The specific surface area of the GAC fillers was130m2/g, the grain density was1.34x103kg/m3and the Iodine adsorption value was137.6mg/g.(2) The metholds of Bentonite (Na) powders blending and acid washing treatments were used to improve the properties improvement of PMS-based GAC for FBBR. The abrasion resistance strength of the fillers increased by15%with8wt%of bentonite (Na) added. During the acid washing treatments, HC1was the most appropriate acid, and he optimum acid washing treatment was carried out prior to activation with2M/L HC1soaking6h. After acid washing treatment, the fillers had a better performance:the specific surface area was176m2/g, the grain density was1170kg/m3and the Iodine adsorption value was218mg/g, and the pore structure of the fillers improved observably.(3) The GAC fillers were used in FBBR to investigate the capacity of wastewater treatment. The GAC fillers were with superior biofilm attachment performance. The COD removal efficiency was about85%after running for18days. The GAC-FBBR system had the best operating conditions with HRT of1h and aeration rate of0.16m3/h. The FBBR was primely resisted to the impact load, the COD and ammonia nitrogen removal efficiency90%, but the TN removal efficiency was20-30%and the TP removal efficiency was20-40%.The prepareation of Paper mill sludge-based granular activated carbon (GAC) fillers was with economic benefit, environmental benefits and social benefits, also it provided approach for realization the reduction, harmless and reutilization of sludge.