Study On Mid-postitioning Aerated Ceramic Suspension And Biological Activated Carbon Dual-media Filter For Water Treatment

In the south area of China，the phenomenon of burst ammonia nitrogen and seasonalorganic pollution is universal existence in drinking water sources．The traditional watertreatment processes in city water plants can no longer provide guarantee for safe drinkingwater．While Ozone-biological activated carbon (O3-BAC) advanced treatment process isapplied in the hot and humid areas of southern China，there will be several problems：First，micro biological leakage；Second，after long-term running of biological aerated filter，the filtermaterial will probably harden；Third，the adsorption capacity of activated carbon willdecreased．To deal with these technical problems，new mid-positioning dual-media filter hasbeen developed．The paper is based on the new technique of mid-positioning dual-mediafilter，optimize double-layer filter media and research the effect of purifying the high and lowdegree of micro polluted source water through lab-scale and pilot-scale test．The result showsthat：(1)The result of the experiment of optimize the thickness of the dual-media filtersuspended ceramic indicates that，suspended ceramic first filter layer can filtrate the turbidityof the filter water，so the carbon layer was well protected．1.5m-thick suspended ceramic firstlayer can guarantee the turbidity <1NTU under12m/h filter rate before the water flowing intothe carbon layer，when it was backwashed，it was in full fluidization state，the turbiditysubstance can be easily exhausted out of the pool．(2)Lab-scale study on double-layer filter carbon type selection indicates that，The meanremoval efficiency of CODMnby3mm columnar carbon，1.5mm columnar carbon and8×16unit shivered carbon were29.4%，31.2%and47.5%respectively．Under the conventional10m/h filter rate，in the10days backwash cycle，the increase of head lose were7.5cm and12.5cm respectively by using3mm columnar carbon and1.5mm columnar carbon，while thebackwash cycle of8×16unit shivered carbon was5days，its head lose was43.0~88.0cm，andthe head lose was increased40.5cm for each average backwash cycle．The required amount ofstable time to restore the normal inlet water after backwash of3mm columnar carbon，1.5mmcolumnar carbon and8×16unit shivered carbon were45min，70min and115min respectively． (3)After21days of the start of the double-layer filter mid-set system，the removalefficiency of the ammonia nitrogen of the effluent water from the filter carbon layer wasgreater than60%，the highest removal efficiency was85.9%． The mean removal efficiencyof turbidity by mid-set system and conventional treatment process water plant were80.4%and71.8%respectively．The mean removal efficiency of CODMnby mid-set system andconventional treatment process water plant were50.1%and46.3%respectively．At the stormperiod，the ammonia nitrogen concentration was suddenly increased，but the mid-set systemcan still make the effluent water meet the requirements of＂drinking water sanitarystandard＂(GB5749-2006)，so the water quality security of drinking water sources was wellprotected．At the same situation，the conventional treatment process water plants need otherstrengthening method to make the ammonia nitrogen concentration at the required level．(4)Study on addition nitrogen into the raw water from the Xijiang River shows that：Ifthe inlet ammonia nitrogen concentration is around3.5mg/L，the double-layer filter can makethe ammonia nitrogen concentration under0.5mg/L efficiently and there was no nitriteacceleration phenomenon during the whole process． If the inlet ammonia nitrogenconcentration is around1.5mg/L，the mid-set system double-layer filter and sand filter canreach the concentration of0.5mg/L after9and13hours respectively．If the inlet ammonianitrogen concentration is around2.5mg/L，the mid-set system double-layer filter and sandfilter can reach the concentration of0.5mg/L after12and14hours respectively．(5)Emergency test on the high pollution sources from the Pearl River shows that：Theaverage value of mid-set system inlet water’s turbidity，CODMnand ammonia nitrogen were1.34NTU，4.69mg/L，4.14mg/L respectively； The average value of mid-positioningdual-media filter effluent water’s turbidity，CODMnand ammonia nitrogen were0.95NTU，3.28mg/L，0.478mg/L respectively，the average removal efficiency were25.7%，30.1%，88.2%respectively；The technique of mid-positioning aerated ceramic suspension andbiological activated carbon dual-media filter has strong ability of anti ammonia nitrogenload．After the technique，the high ammonia nitrogen concentration water from the PearlRiver，its ammonia nitrogen concentration can be reduced to0.5mg/L．...