Sludge Digestion Filtrate Treatment Through ANAMMOX:Practical Application And Process Optimization

Anaerobic ammonia oxidation(anammox)is a novel biological nitrogen removal technology from wastewater.The application of anammox in full-scale wastewater treatment is one of the hot issues but engineering application,start-up strategies and process development of full-scale anammox process are still rare.In this study,full-scale treatment of high ammonia nitrogen wastewater base on anammox was was studied,especially the process start-up methods and problem solving strategies.Besides,three novel anammox processes were proposed to solve the engineering problems and related test studies were carried out.In this study,a novel anammox process was established base on core technology of immobilized anammox carriers,which was named as RenocarTM autotrophic nitrogen removal process.First full-scale sludge digestion filtrate treatment through anammox process(RenocarTM)in China was studied,including start-up method and nitrogen removal performance.The partial nitrification and anammox process were start-up sequentially by inoculating excess sludge and anammox granular sludge and the full-scale process had a treatment capability of 500 m3/d.At the initial stage of system start-up,NO2--N accumulation was achieved by controlling DO less than 0.2 mg/L udner30? and a nitrogen loading rate of 0.42 kg N/(m3·d).When AnAOB granular sludge was added,the effluent concentration of NO2--N decreased to 28.9 mg/L.After an operation period 34 d of,the total nitrogen(TN)removal rate and TN removal efficiency were 0.44 kg N/(m3·d)and 82.7%,respectively.Three different kinds of anammox processes were studied in this study for treating thermal hydrolysis sludge digestion filtrate.The thermal hydrolysis sludge digestion filtrate contained a high concentration of refractory organic matter,which presented an obvious inhibitory effect on the activity of AnAOB.Full-scale thermal hydrolysis sludge digestion filtrate treatment based on anammox process has been rarely reported all over the word.Three strategies of raw water dilution+RenocarTM process,ozone pretreatment+RenocarTM process and individual RenocarTM process were studied in this study.Results showed that both of raw water dilution and ozone pretreatment could reduce inhibitive effect of filtrate on AnAOB.The highest total nitrogen removal rate were 0.30,0.42,0.24 kg N/(m3·d),respectively.In the full-scale reactor treating wastewater of 1750 m3/d,WWTP secondary effluent and thermal hydrolysis sludge digestion filtrate were mixed with a ratio of t1:1.The hybrid wastewater flow into RenocarTM process.and TN removal rate reached 0.30 kg N/(m3·d)with NH4+-N and TN removal efficiency of 86%and 78%,respectively.Due to the application of side stream treatment,TN concentration of secondary effluent of WWTP was reduced by 3 mg/L.After 4 months' operation,AOB was effectively enriched in floc and the relative abundance increased to 96.6%.NOB was washed out due to FA inhibition with a relative abundance of 0.3%.Abundances of AnAOB were 1.44 × 109 and 2.74 × 1010 cells/g MLSS in floc and biofilm,respectively.AnAOB was mainly distributed in biofilm.In this paper,the practical experiences of RenocarTM process engineering was summarized,and three novel anammox processes were constructed aiming at realizing three optimization objectives which were reducing project investment,increasing nitrogen removal efficiency and expanding application fields.A novel anammox process was developed with combination of floc and granule.Granular sludge replaced the immobilized carriers to enrich and maintain anammox bacteria.The study found that the inoculation proportion was positively correlated with the total nitrogen removal rate at the initial start-up period.The hydraulic washing effect was the main factor to promote the formation of granular sludge in the reactor.The total nitrogen removal rate of the laboratory scale reactor treating simulated high-strength ammonia wastewater could reach up to 2.6 kg N/(m3·d).The process could be operated stably in two modes:intermittent and completely hybrid.FA concentration,DO concentration and aeration shear strength were the main factors affecting the nitrogen removal rate and particle size of the sludge.A novel multistage aerobic and micro-oxygen anammox process was developed.The plug-flow reactor was divided into several group of "aerobic and micro-oxygen"chamber.In the aerobic region,DO was controlled over 1.5mg/L to provide the optimal reaction conditions for AOB.Comparatively,DO was lower than 0.2mg/L and the fixed carrier was installed in micro-oxygen region,which could provide the optimal environment for growth of anammox bacteria.The dilute thermal hydrolysis sludge digestion filtrate as the influent,the process was successfully started in 114th day with inoculation of mature anammox carrier.The total nitrogen removal rate of the system was up to 0.5 kg N/(m3·d),which was 60%higher than RenocarTM process.Due to the sludge digestion filtrate could produce high-strength FNA by the partial nitrification.In this study,the process of partial nitrification-anammox treating sewage based on side-stream FNA inhibition was studied in a pilot-scale platform of 102 m3.The mainstream activated sludge was continuously inhibited in side-stream with MLSS of 20000 mg/L and duration time of 48 h at anoxic condition,The nitrite accumulation rate of pilot-scale system was 67%on the 52th day.In the couple of partial nitrification and anammox pilot-scale process,NH4+-N and TN of effluent were lower than 5 and 15 mg/L,respectively,which could meet the first-class grade A of national sewage discharge standard.