Study On Ammonium Removal Process From Light Polluted Water Source At A Low Concentration

With rapid development of economy, the pollution of water sources such as NH₄⁺ （NH3） pollutant is increasingly serious as well as population dramatically increasing and living condition greatly improved. Water supply system has been out of capacity both in water amount and water quality. China and many other countries have already established strict limitation of NH₄⁺-N or NH3 in drinking water criterion.In order to find suitable method and process for ammonium removal from water source, synthetic water containing NH₄⁺-N at about 10ppm was treated by two combination techniques.Method 1:①NH₄⁺-N was nitrified to NO₃^--N by immobilized microbiological pellets in inner-circulated fluidized bed reactor continuously;②NO₃^--N was removed by IRA400JCl ion exchange resin in columns and the resin regenerated by 3⁵%NaCl solution;③regeneration waste brine was treated by biological denitrification in SBR reactor before being drained to environment.①It showed an efficient and stable NH₄⁺-N nitrifying performance under the condition of temperature 20³0℃and DO 3⁴mg/L. Removal rate reached above 90% within HRT30min when influent NH₄⁺-N at 10¹5mg/L and both NH₄⁺-N and NO₂^--N was below 0.25 mg/L in the effluent within HRT27min when influent below 10mg/L. pH value of effluent water remained at 7.2⁷.3 automatically. Removal loading could reach 256.1mg-N/（L-pellet·h） and oxygen uptake rate raise to 1170.9mg-O₂/（L-pellet·h）. The nitrifying process fit to zero-grade degradation kinetics. High biomass retention was observed in SEM.②NO₃^- removal by IRA400JCl ion exchange resin was efficient and the process fit to Langmuir well. About 675 bed volumes （BV） raw water could be treated before effluent NO₃^- above 10mg-N/L. Breakthrough capacity could reach 19.99kgNO₃^--N/m³-resin, and the removal rate was about 98.709%. The resin saturated with NO₃^- was regenerated smoothly and conveniently with 3⁵% NaCl solution.③The regeneration waste brine could be treated by the anaerobic biological denitrification in SBR after 2 months’cultivation and climation. 2.5m³ biological reactor and 0.25m³ ion exchange columns were necessary while NH₄⁺-N removal capacity is 120t/d. The SV for biological part was about 48m³/m³·d while 480m³/m³·d for ion exchange part.Method 2:①NH₄⁺-N was absorbed continuously by 150g new clinoptilolite at a size of 0.55¹.30mm filled in multiple smart columns in parataxis style;②clinoptilolite was regenerated with saturated NaCl solution when full of adsorption;③NH₄⁺-N removal again by regenerated clinoptilolite;④regeneration again…To be recycled and circulated. The regeneration waste brine was treated by ammonia escaping from alkaline solution with heat.①NH₄⁺ adsorbed by new clinoptilolite in columns gradually, 92.67L water was treated after 32.5h when effluent got to 1mg-N/L. The maximum adsorption capacity was about 12.76mg-N/ （g-zeolite）. SV was about 421.6m³/m³·d.②Clinoptilolite was regenerated with saturated NaCl solution smoothly and efficiently. The recovery rate increased above 90% after 130min. The NH₄⁺-N in regeneration brine got to its maximum of 4966mg-N/L. 1.875kgNaCl/（L-zeolite） were used for regeneration and the waste brine was totally about 7.76BV.③About 193.28L water was treated within 63h by Clinoptilolite after regeneration. The maximum capacity was 15.56mg-N/（g-zeolite） and SV was 460.19m³/m³·d.④clinoptilolite saturatd with NH₄⁺ was Regenrated. Recovery rate increased above 90% after 150min. About 300.4gNaCl was used for regeneration of 90g clinoptilolite and the waste brine was about 10.3BV. There was an accumulation phenomenon of NH₄⁺-N in brine in one column after another and the maximum could reach 6000mg-N/L. The zeolite system was efficient, safe, low cost and convenient, especially fit to small scale water supply system. If the NH₄⁺-N removal capacity was about 120t/d, 0.342m³ adsorption reactor was necessary. SV was about 350.9m³/m³·d.In a word, both two methods were stably efficient for NH₄⁺ removal at a low concentration. The process was simple, economical and feasible for engineering application.