Efficient Nitrogen Removal of Reject Water Generated from Anaerobic Digester Treating Sewage Sludge and Livestock Manure by Combining Anammox and Autotrophic Sulfur Denitrification Processes

Abstract

The reject water from anaerobic digestion with high (Total Nitrogen) TN concentration was treated by a demonstration plant combining the anammox process and SOD (SOD®; Sulfur Oxidation Denitrification) process. The anaerobic digestion was a co-digestion of livestock wastewater, food waste water, and sewage sludge so that the TN concentration and conductivity of the reject water were very high. This anammox plant was the first anammox demonstration plant in South Korea. The maximum TN removal efficiency of 80% was achieved for the anammox reactor under nitrogen loading rate (NLR) of 0.45 kg-N/m3·d. As a result of decreasing the dilution of the reject water, the influent conductivity and NLR values were increased to 7.8 mS/cm and 0.7 kg/m3·d, causing a rapid decrease in the TN removal efficiency. The sludge concentration from the hydro-cyclone overflow was about 40 mg-MLVSS/L in which small sized anammox granules were detected. It was proven that the increase in (Mixed Liquor Volatile Suspended Solids) MLVSS concentration in the anammox reactor was not easy under high influent conductivity and NLR. 97% of NO2−-N+NO3−-N generated from the anammox process could be treated successfully by the SOD reactor. A TN removal efficiency of 35% under poor annamox treatment could increase to 67% by applying the SOD reactor post treatment for the removal of NO3−-N. The dominant anammox bacteria in the anammox reactor was identified as Brocadia fulgida and 9.3% (genus level) of the bacteria out of the total bacteria were anammox bacteria.

Evaluation of a Full-Scale Suspended Sludge Deammonification Technology Coupled with an Hydrocyclone to Treat Thermal Hydrolysis Dewatering Liquors

“…However, comparisons of this study with [20] are limited due to differences in the activity test methodology. When treating manure digestate dewatering liquors, Kwon (2019) [22] measured up to 90% of AMX retention in a system with an hydrocyclone, however there was also instability with periods of excessive AMX washout. The biomass washout for the different biomass types (e.g., AMX, AOB, and NOB) and Period 4 and Period 5 are presented in Figure 5.…”

“…In a modelling study, Van Winckel (2019) [18] evaluated the impact of different SRTs on the biomass type (AOB, AMX, and NOB) and identified that greater AMX retention of 88-91% could lead to the enhanced nitrogen removal rate of 1.04-1.16 kg N m −3 d −1 . However, AMX washout from a hydrocyclone has also been observed [22]. Past studies that evaluated hydrocyclones are limited and relied on different ex-situ activity measurement methods with sample sizes of <5.…”

Perspectives and actions moving forward

“…However, cyclones cannot retain all anammox bacteria, i.e. small anammox granules could be easily wasted out through overflows from the cyclones (Kwon et al, 2019), potentially leading to system failure. By contrast, anammox biocarriers could be easily retained in the system by screens (Han et al, 2016;Lemaire et al, 2014), indicating that the loss of anammox bacteria could be avoided.…”

Thiosulphate driven autotrophic denitrification via nitrite using synthetic wastewater

“…It has been suggested that the implementation of autotrophic denitrification or denitritation via sulphur for wastewater characterized by low COD/N ratio, could be very effective 14–16 . Wastewaters from a variety of industrial activities, such as mineral processes, sludge reject water, and landfill leachate, are effluent streams that due to their low C/N rate content will require the addition of an external carbon source during their treatment via heterotrophic denitritation/denitrification 3,17 .…”