Method Research On The Removal Of Hardness In The Scaling Groundwater

This research is to find the methods for the removal of hardness of groundwater.The experiment studied the removal efficiency on temporary hardness of scaling groudwater by coagulation precipitation process;This research found out the Acid-Adjustable-Aeration method for the removal of temporary hardness of scaling groudwater;This research also studied the removal efficiency on temporary hardness of scaling groudwater by biomineralization bacteria,utilized the Acinetobacter sp.novelly for the removal of hardness and nitrate simultaneously.The results indicated that strain H36 was most closely related to Acinetobacter antiviralis strain KNF 2022(NR 115739)(similarity 100%).Therefore,strain H36 is proposed to be an Acinetobacter species.The results indicated that strain CN86 was most closely(above 99%)related to Acinetobacter antiviralis strain ATCC23055(NR117619).Therefore,strain CN86 is proposed to be an Acinetobacter species.Strain H36 was confirmed to have the ability to perform simultaneous denitrification and biomineralization.Strain H36 had the capability to completely reduce 96.29% of NO3––N and 78.59% of hardness over 112 h at the aerobic condition.Response surface methodology(RSM)analysis demonstrated the highest removal ratio of hardness was obtained with hardness concentration of 350 mg/L,pH8.5,organic concentration of 0.75 g/L and inoculum size of 15%.The highest removal ratio of nitrate was obtained with hardness concentration of 350 mg/L,pH 7.5,organic concentration of 0.75 g/L and inoculum size of 10%.Besides,X-ray diffraction(XRD)analysis showed calcium carbonate could be formed in the process of biomineralization.The result showed that the bacterial strain H36 has a good application prospect in water treatment.Strain CN86 was confirmed to have the ability to perform simultaneous denitrification and biomineralization.Exponential decay equation was used for the matching of kinetic processes on denitrification and biomineralization.The fitting results showed that kinetic of denitrification and biomineralization all follow the exponential decay equation.Most of the correlation coefficient R2 were more than0.90.A highest nitrate removal rate was achieved at the pH 7.0,organic concentration of 1.5 g/L and temperature of 30?.A optimal hardness removal rate was abtained at the pH 9.0,organic concentration of 2.0 g/L and temperature of 30 ?.In the groundwater experiments,strain CN86 was proved to have a strong ability in the simultaneous removal of nitrate and hardness.Coagulation settling test was used to remove the temporary hardness in the raw water,the results showed that the best coagulant was PAC,when PAC 50 mg/L,PAM40 mg/L,the turbidity of water reached the lowest,at 4.61 NTU,less than 10 NTU.Groundwater temporary hardness somewhere in xian region was disposed with a novel method — Acid Adjustable Aeration.Static beaker test was conducted in the laboratory to value the effects of different operation procedure,volume of the acid and aeration quantity on the test efficiency.The results indicated that the optimal consequence was obtained at 1100 ?L/L of acid and a 5:1 of air-to-water ratio.Dynamic reactor experiment was also carried out in the laboratory.The reactor worked 6 h per day for a week.The pH of effluents was 7.70 and 7.63 when the air-to-water ratios were 3:1 and 6.4:1 respectively with a same acid quantity of 900?L/L.And the temporary hardness of groundwater after treatment was under the concentration of 0.2 mg/L.