Preparation Of Sludge Based Biochar By Foaming Drying Coupled With Pyrolysis

Sludge is a dangerous waste with high moisture content.The traditional sludge drying technology has the disadvantages of low drying efficiency and high energy consumption.How to reduce the energy consumption in sludge drying and the resource utilization of dried sludge are the key issues in the treatment and disposal of sludge.This study is based on the above questions.In this study,foaming pretreatment was used to sludge drying.The effects of additives on sludge foaming drying behavior and the physical and chemical properties of sludge based biochar were investigated.Sludge based biochar was used for the adsorption of Pb²⁺,and the adsorption behavior was studied.The FTIR,XPS,and XRD analysis was used to explore the adsorption mechanism.The results and conclusions are as follows.（1）Adding NaOH into sludge can effectively realize foaming pretreatment,while adding too much NaOH is not conducive to the stability of foams.The optimum addition amount of NaOH is 1.5 wt%.（2）Torrefaction pretreatment can effectively improve the quality of sludge pyrolysis products.Obvious deoxidation effect can be achieved at the torrefaction temperature of 300 ^oC.Foaming pretreatment is not conducive to the adsorption of tetracycline by sludge based biochar.（3）Adding Camellia oleifera shell biochar can further improve the drying efficiency of foamed sludge,and improve the quality of sludge pyrolysis products.The adsorption behavior of Pb²⁺adsorbed onto sludge based biochar can be well described by pseudo-second-order kinetic model and Langmuir isotherm model with the maximum adsorption capacity of 179.33 mg/g.Therefore,the sludge based biochar prepared in this study is a potential adsorption material with high adsorption performance,and is expected to be used for the removal of volatile organic compounds and exhaust gases in vehicles.