The Application And Optimization Of Acid-alkali Balance Aeration Method In A Miniature Scale Removal Equipment

Groundwater is one of the common drinking water sources in China.Most of the total hardness of water supply system with groundwater is in accordance with the "Standards for drinking water quality" in China,but there is a widespread problem of high scale,which brings a lot of inconvenience to people's production and life.In order to solve the contradiction between the user's demand for water quality and the total water hardness standard of the water supply system,according to the principle of Acid-alkali balance aeration method,a miniaturizing scale removal equipment had been designed and made.Experiment site was in two groundwater supply plant A and B in Shaanxi Province,in which boiling water has more scale.In the experiment,the water from A and B is treated by this equipment,and the quality of treated water is tested,furthermore,this paper analyzed and optimized the key operating parameters of the equipment,such as the dosage of scale inhibitor,the air to liquid ratio and the hydraulic retention time.Stability experiment has been down in a long-term operation of the equipment.In order to reduce the cost of equipment operation,we designed three test method to study the influence of on the quality of equipment running,include adding polyhedral hollow ball packing,the adoption of intermittent aeration and addition of mixed acid as scale inhibitor.The main conclusions of this paper are as follows:(1)The operation effect of the equipment in A and B shows that the equipment can better improve the scaling phenomenon of the two kinds of water sources in A and B.For A,B two kinds of water source,the dosage was about2.0‰~2.3‰ and 1.4‰~1.6‰ respectively,and the gas-water was in the range of 6:1~7:1 and 5:1~6:1 correspondently,the appropriate operating time of the equipment was 18min~22min,the tests showed that the alkalinity of the effluent decreased to below 138mg/L and 154mg/L respectively,the turbidity of cold-boiling water after treatment can be maintained below 1.0NTU,the pH of treated water was close to raw water.The result of long-term operation showed that the operation of the equipment was stable.(2)Adding polyhedral hollow ball packing could increase the contact area and the contact time of gas and liquid,and gas removal efficiency could be improved.The pH value of the effluent is increased about 0.05~0.07 compared with the pH value without filler operation,which can effectively reduce the running cost.The experimental results showed that the intermittent aeration could effectively improve the effluent pH value.The effluent pH value tended to be stable with the decrease of the aeration-stopping time.The longer the HRT,the higher the pH of the intermittent aeration.When the aeration-stopping time was less than 1min and the hydraulic retention time was about 18min~22min,the effluence of intermittent aeration was the best.Different volume ratios of hydrochloric acid and sulfuric acid were used as scale inhibitor in the equipment,real-running results show that there is no significant difference between alkalinity,hardness,turbidity,after boiling turbidity and effluent pH compared to original scale inhibitor,the results of continuous operation show that the water quality is stable.Different volume ratios of hydrochloric acid and sulfuric acid could replace hydrochloric acid scale inhibitor.(3)In order to promote the equipment better,auto-control project of the equipment running had been designed based on the aforementioned experimental results.Each unit of acid-alkali balance aeration method was integrated and equipment with power-supply module and automatic control system.