Study On Phosphorus Removal By Aluminum Matrix Diatomite Sludge

Phosphorus is one of the essential nutrients for aquatic organisms,but excessive phosphorus can lead to eutrophication of the water and even endanger human health.We must find a suitable method to remove excessive phosphorus in the water.Among the many phosphorus removal methods,adsorption method is widely concerned.Looking for efficient and environmentally friendly new adsorption materials has become an urgent task for the phosphorus removal method.Diatomite has a large specific surface area and pore channels.At the same time,it has stable chemical properties and is cheap and easy to obtain.It is a good adsorbent substrate,but its adsorption capacity is limited.By modifying diatomite and supporting metal oxides,The diatomite plays a physical and chemical role in the process of adsorbing and removing phosphorus at the same time,which can greatly improve the performance of diatomite's adsorption and removal of phosphorus,which is of great significance for solving the problem of eutrophication.In this experiment,three kinds of flocculants,polyaluminum chloride?PAC?,polyferric sulfate?PFS?,and aluminum chloride?Al Cl₃?were used to modify diatomite to obtain three kinds of iron-aluminum matrix diatomite sludge.Investigate the effect of p H value and initial concentration of phosphorus solution on the phosphorus removal efficiency of sludge.Based on the experimental results,choose a sludge with the best phosphorus removal effect.The effects of p H,initial concentration of phosphorus solution,stirring intensity,sludge dosage,and coexisting anions on the efficiency of phosphorus removal were studied separately.The optimal conditions for phosphorus removal were determined according to the orthogonal experiment method.An adsorption kinetics and thermodynamic model for the removal of phosphorus by sludge was established.The experimental results show:1. PAC diatomite sludge?ADS?has the best phosphorus removal effect.The p H value has a great influence on the adsorption efficiency.The phosphorus removal efficiency reached 83.0%and 80.9%at p H 6 and 8,respectively.As the initial concentration of phosphorus solution increased,the removal rate of phosphorus gradually decreased.When the sludge dosage was 2.0 g/L,and the initial phosphorus solution concentration increased from 10 to 50 mg/L,the removal rate decreased from 82.2%to 53.1%.2. The best conditions for phosphorus removal by ADS:dosing amount is 3.0g/L,p H 8,initial phosphorus concentration is 10 mg/L,and stirring intensity is 120r/min.At this time,the removal rate of phosphorus by ADS was 83.4%.At p H 2 and6,the removal rate of phosphorus decreased rapidly with the increase of stirring intensity.When the stirring speed was increased from 30 to 100 r/min,the reduction rate of phosphorus removal rate of the two p H systems was 20.3%and 9.1%,respectively;while p H=10,the decline is only 5.1%.3. The larger the amount of ADS added,the higher the removal rate of phosphorus.When the ADS increased from 1.0 to 6.0 g/L,the removal efficiency of phosphorus increased from 51.8%to 80.8%during adsorption equilibrium.4. When the concentrations of coexisting anions S^2-,Cl^-,SO₄^2-,and NO₃^-increased from 20 to 100 mg/L,respectively,the removal rate of phosphorus by ADS decreased to varying degrees,and the order of the effect on phosphorus removal5. The principle of phosphorus adsorption by ADS is mainly chemical deposition reaction and electrostatic adsorption.Chemical adsorption plays a leading role.The adsorption process conforms to the Langmuir isothermal adsorption model and quasi-second-order kinetic model.The maximum adsorption capacity is 15.54mg/g,and its maximum theoretical equilibrium adsorption capacity is 15.97 mg/g.