| The freezing method is a new type of wastewater treatment technology that uses the principle of solid-liquid phase equilibrium in physical chemistry as the theoretical basis to realize the concentration and separation of pollutants under freezing point.This study used nutrient in wastewater as the research object,treated the simulated wastewater which is riched in ammonia nitrogen,phosphorus and potassium,studied the influencing factors,and explored the feasibility of recycling nutrient elements in wastewater..Treated and concentrated the simulated ammonia nitrogen wastewater by freezing method.The effects of freezing temperature,freezing time and solution concentration on the concentration and removal of ammonia nitrogen simulated wastewater were investigated.The concentrates coefficient was 2.3,when the freezing temperature was-12?,the freezing time was 5 hours,and the ammonia nitrogen concentration was 400 mg/L;The ammonia nitrogen removal rate of the ice melt water was 96%or more,and,it reached the secondary comprehensive discharge standard.The theoretical electric power by this cryogenic freezing process is 16.1 kW.Phosphate simulated wastewater was used as the research object,simulated phosphate wastewater was treated by chemical precipitation method and progressive freezing method.Phosphorus-containing wastewater was treated by chemical precipitation.The results showed that with the increase of pH value,the total phosphorus removal rate rapidly increased and gradually decreased;the lower the temperature,the two selected temperatures have no significant affect on the treatment effect;the reaction time had little effect on the treatment effect.Progressive freezing treatment of phosphorus-containing wastewater showd that with the reduction of the frozen layer,the total phosphorus content increases,the concentration factor was greater than 2.0.The higher the concentration of phosphate in the water,the better the treatment effect.Comparing the two treatment methods,it can be seen that the progressive freezing method does not add any chemical agents,does not produce secondary pollution,and has a large application advantage.The application of low temperature suspension crystallization method to treat simulated potassium sulfate wastewater shows that when the ice formation rate is 62.2%,the removal rate of potassium ion was 83.5%,and the removal rate of conductivity was 81.4%by the suspension crystallization method;While obtaining a concentrated solution with a higher concentration,a large amount of potassium sulfate crystals was continuously precipitated at the bottom of the device,and the precipitation rate was 6.8 g/L.The theoretical electric power by the low-temperature freezing process is 18.9 kW.The wastewater from napropamide production were pretreated by suspension crystallization method,investigated the effect of suspension crystallization on the potassium ion,COD,pH,and conductivity in waste water at different ice formation rates,reduced the amount of incineration and improved its biodegradability.The concentration ratio of COD of concentrate could be 3.4.The removal rates of COD?K+ and the electroconductibility of the effluent is about 90%,which is suitable for biochemical treatment in the comprehensive regulation pond.When the ice formation rate was 61.3%,the precipitation rate of napropamide production wastewater is 89g/L,and the separated crystal was tested to be mainly a mixture of potassium chloride and potassium hydrogen carbonate.Under the ice formation rate,the calorific value of the concentrated solution was increased by 129%and the incineration was reduced obviously.The theoretical electric power by the low-temperature freezing process is 18 kW.The suspension crystallization process for the treatment of napropamide synthetic wastewater could improve the biodegradability of wastewater while recovering the mixture of potassium chloride and aliphatic amide.therefore,which had a good application prospects. |
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