Combined Anaerobic/Aerobic Digestion: Effect of Aerobic Retention Time on Nitrogen and Solids Removal

Abstract

A combined anaerobic/aerobic sludge digestion system was studied to determine the effect of aerobic solids retention time (SRT) on its solids and nitrogen removal efficiencies. After the anaerobic digester reached steady state, effluent from the anaerobic digester was fed to aerobic digesters that were operated at 2-to 5-day SRTs. The anaerobic system was fed with a mixture of primary and secondary sludge from a local municipal wastewater treatment plant. Both systems were fed once per a day. The aerobic reactor was continuously aerated with ambient air, maintaining dissolved oxygen level at 1.1 6 0.3 mg/L. At a 4-day or longer SRT, more than 11% additional volatile solids and 90% or greater ammonia were removed in the aerobic digester, while 32.8 mg-N/L or more nitrite/nitrate also was measured. Most total Kjeldahl nitrogen removal was via ammonia removal, while little organic nitrogen was removed in the aerobic digester. Water Environ. Res., 83, 802 (2011).

Anaerobic digestion of food waste with aerobic post-treatment: Effect of fruit and vegetable content

“…This observation concurs with the findings of Shen et al (2013) and Wang et al (2014) showing the benefits of mixing food waste with FVW. Also, VS, TS and COD removal rates stabilized with averages of 83 ± 1.5%, 81 ± 1.6%, and 87 ± 1.6%, respectively, which are close to pre-inhibition rates and similar to the reported figures for mesophilic AD of FW and FVW (Ganesh et al, 2014; Kim and Novak, 2011; Serrano et al, 2014; Shen et al, 2013; Wang et al, 2014).…”

Sequential Anaerobic/Aerobic Digestion for Enhanced Carbon/Nitrogen Removal and Cake Odor Reduction

“…In Scenario 1, the sequential ME-ME and TH-TH AN/ AERO configurations achieved 9.2À10.9% higher VS removals than Control 1 (ME) and Control 2 (TH), respectively. Hence, it was observed that the overall VS removal of sequential AN/ AERO process increased with an increase in SRT of AERO digesters, which supports the literature (Kim and Novak, 2011). In removal over the respective control section of Figure 3, removal of VS in TPD (TH-ME) is with respect to Control 2 (TH).…”

“…As expected, the removal of ammonia by AERO digesters of sequential AN/AERO systems decreased with a decrease in SRT of AERO digesters from 5.1 (Scenario 1) to 3.4 and 1.7 d in Scenarios 2 and 3, respectively (Figure 6). Kim and Novak (2011) also suggested that ammonia removal by AERO digesters decreases with the decrease in SRT.…”

Post aerobic digestion (PAD) is a solids sidestream nutrient removal process that utilizes native carbon: performance and key operational parameters from two full-scale PAD reactors

“…These conditions result in nitrogen removal without the need to provide an external carbon source and was postulated to be to the result of simultaneous nitrication and denitrication. 30 Biological processes, such as anaerobic digestion, have a known range of healthy operating conditions and loading capacities, it is necessary to identify important operational parameters for PAD to understand capability, design, and trouble-shooting approaches. Moreover, full-scale analysis is required to know real-world process capabilities for nutrient loading and removal.…”