Development And Application Of High-efficiency Phosphorus Removal Adsorbent Based On Shiitake Mushroom Residue

Edible fungus residue is a new solid waste produced with the booming development of edible fungus industry,which has large yield and high environmental risk.Therefore,it is urgent to develop green and efficient resource utilization ways to promote the green development of edible fungus industry.Taking Mushroom residue（MR）as the research object,this study firstly made a comprehensive analysis of its physical and chemical properties,then carbonized it successively at high temperature and intensified it by ball milling to obtain efficient dephosphorization carbon material based on mushroom residue,and carried out in-depth analysis of the adsorption mechanism,as follows:（1）The physicochemical properties of MR And the adsorption results of phosphorus show that MR Contains rich mineral components such as alkali metals and alkaline earth metals（especially K,Na,Ca and Mg,whose contents are 245.35,50.18,1390.63 and 29.84 mmol/g,respectively）,and the content of Ca is higher than that of ordinary biomass.The main existing forms are CaC₂O₄（H₂O）,CaSO₄and Ca₂SiO₄,which are weakly basic（pH=6.79）.The surface of MR has certain pore structure,and the specific surface area is 2.94m²/g.During the pyrolysis process,the main pyrolysis range of MR is 244.95-350.67℃,and the maximum pyrolysis rate and corresponding temperature are-3.7595%/min and 303.42℃,respectively.When MR is applied to the treatment of wastewater containing phosphorus,the effect is poor and the removal ability of phosphorus is basically not available.（2）The MR Was carbonized at high temperature（800-1000℃）to prepare Mushroom residue based biochars（MRCs）for the treatment of wastewater containing phosphorus.Physicochemical analysis showed that the MRCs were rich in K,Na,Ca,Mg and other minerals,especially Ca,which was as high as 4328.43-4919.38 mmol/kg.Camainly exists in the form of CaCO₃in MRCs.With the increase of pyrolysis temperature,part of Ca is decomposed into CaO.In addition,MRCs also have high pH_pzc（11.86-12.04）,developed pore structure（specific surface area of 167.56-223.80m²/g）and abundant surface functional groups（such as C=O,C=C,C-O,Ca-O,etc.）.In the process of phosphorus adsorption,the adsorption capacity of biochar follows MRC-800<MRC-900<MRC-1000,and can be well fitted by Langmuir adsorption isotherm model and quasi-second-order kinetic model.That is,the adsorption process is a single-layer adsorption dominated by chemical action.The theoretical maximum adsorption capacity of MRC-800,MRC-900 and MRC-1000 for phosphorus is 104.17,121.95 and 128.21 mg/g,respectively.Electrostatic interaction,pore packing,coordination and Ca-induced precipitation（forming CaHPO₄ and Ca₅（PO₄）₃（OH））play an important role in this process.（3）In order to improve the phosphorus removal ability of mushroom residue based biochars,ball-milling mushroom residue-based biochars（B-MRCs）were prepared by Ball milling for the preparation of porous mushroom residue based biochars（B-MRCs）for phosphorus wastewater treatment.The results showed as follows:After ball milling,the particle size of biochar powder decreased significantly,the surface functional group content increased and the distribution of particulate matter was more uniform,which exposed a large number of calcium-containing minerals in the biochar and provided more adsorption sites to increase the adsorption capacity.Under the conditions of milling time of 2 h,rotation speed of 300 r/min and pellet feed ratio of 1:10,the adsorption capacity of biochar for phosphorus was the best,and the adsorption capacity was 178.89mg/g.The adsorption isotherm parameters showed that the adsorption performance of biochar modified by ball milling increased by 71.73%,and the modification effect was significant.The phosphorus adsorption mechanism of biochar after ball milling includes surface coordination,pore packing,electrostatic attraction and Ca-P precipitation.The main components of the sediments after adsorption reaction are CaHPO₄,CaPO₃（OH）₂H₂O and part of Ca₅（PO₄）₃（OH）.This study showed that high temperature carbonization of biochar for the treatment of phosphorus containing wastewater is a feasible resource utilization approach of edible bacteria residue,and ball milling can further improve the performance of edible bacteria residue based carbon materials.