Upflow packed bed Anammox reactor used in two-stage deammonification of sludge digester effluent

Abstract

The sludge digester effluent taken from a full scale municipal wastewater treatment plant (WWTP) in Istanbul, Turkey, was successfully deammonified using a laboratory scale two-stage partial nitritation (PN)/Anammox (A) process and a maximum nitrogen removal rate of 1.02 kg N/m3/d was achieved. In the PN reactor, 56.8 ± 4% of the influent NH4-N was oxidized to NO2-N and the effluent nitrate concentration was kept below 1 mg/L with 0.5–0.7 mg/L of dissolved oxygen and pH of 7.12 ± 12 at 24 ± 4°C. The effluent of the PN reactor was fed to an upflow packed bed Anammox reactor where high removal efficiency was achieved with NO2-N:NH4-N and NO3-N:NH4-N ratios of 1.32 ± 0.19:1 and 0.22 ± 0.10:1, respectively. The results show that NH4-N removal efficiency up to 98.7 ± 2.4% and total nitrogen removal of 87.7 ± 6.5% were achieved.

Evaluation of Sludge Digester Effluent as Feeding Solution for the Enrichment of Anammox Bacteria

“…Numerous studies reported that the start‐up of the anammox process in a bioreactor is usually time‐consuming and may take from months to years due to the low growth rates of anammox bacteria (the average doubling time is 11 days) . It also requires suitable environmental conditions of low dissolved oxygen (DO) concentration, with temperature and pH intervals of 30–40 °C and 7–8, respectively …”

“…However, recent studies have reported rapid and successful enrichment and operational strategies and factors influencing the anammox enrichment process. Examples include using different seeding sludge as inoculum, reactor type, medium carrier, and optimal operational conditions, determining the effect of various parameters, as hydraulic retention time, feeding load, DO, temperature . İbrahim et al., Çelen‐Erdem at al., Egli et al., and Uyanik et al .…”

“…Examples include using different seeding sludge as inoculum, reactor type, medium carrier, and optimal operational conditions, determining the effect of various parameters, as hydraulic retention time, feeding load, DO, temperature . İbrahim et al., Çelen‐Erdem at al., Egli et al., and Uyanik et al . used synthetic wastewater, which contains trace elements, chemicals and tap water, as feeding solution during the lab‐scale anammox enrichment studies.…”

“…[7] It also requires suitable environmental conditions of low dissolved oxygen (DO) concentration, with temperature and pH intervals of 30-40°C and 7-8, respectively. [11] The unavailability of large volumes of slowly growing anammox seed causes long start-up period and thus limits the practical application of anammox process in most of the countries worldwide. However, recent studies have reported rapid and successful enrichment and operational strategies [8] and factors influencing the anammox enrichment process.…”

“…Examples include using different seeding sludge as inoculum, [4,9] reactor type, medium carrier, and optimal operational conditions, [10] determining the effect of various parameters, as hydraulic retention time, feeding load, DO, temperature. [6,[11][12][13]İ brahim et al, [6] Çelen-Erdem at al., [11] Egli et al, [14] and Uyanik et al [15] used synthetic wastewater, which contains trace elements, chemicals and tap water, as feeding solution during the lab-scale anammox enrichment studies. To the best of author knowledge, an economical and easily handled feeding solution to produce large volumes of anammox bacteria especially in view of the process scale-up has not been reported previously.…”