Evaluation of anaerobic digestion processes for short sludge-age waste activated sludge combined with anammox treatment of digestate liquor

Abstract

The need to reduce energy input and enhance energy recovery from wastewater is driving renewed interest in high-rate activated sludge treatment (i.e. short hydraulic and solids retention times (HRT and SRT, respectively)). This process generates short SRT activated sludge stream, which should be highly degradable. However, the evaluation of anaerobic digestion of short SRT sludge has been limited. This paper assesses anaerobic digestion of short SRT sludge digestion derived from meat processing wastewater under thermophilic and mesophilic conditions. The thermophilic digestion system (55°C) achieved 60 and 68% volatile solids destruction at 8 day and 10 day HRT, respectively, compared with 50% in the mesophilic digestion system (35°C, 10 day HRT). The digestion effluents from the thermophilic (8-10 day HRT) and mesophilic systems were stable, as assessed by residual methane potentials. The ammonia rich sludge dewatering liquor was effectively treated by a batch anammox process, which exhibited comparable nitrogen removal rate as the tests using a control synthetic ammonia solution, indicating that the dewatering liquor did not have inhibiting/toxic effects on the anammox activity.

Harvesting microalgae using activated sludge can decrease polymer dosing and enhance methane production via co-digestion in a bacterial-microalgal process

“…This leads to the loss of the energy potential of the activated sludge [9] together with the loss of nutrients (nitrogen and phosphorus) [8]. Short solids retention time (SRT) activated sludge systems propose a solution whereby rather than the oxidization of organic carbon, activated sludge preserves the organic carbon promoting higher potential for energy recovery [10].…”

Anaerobic-aerobic sequential treatment: Temperature optimization and cost implications

“…The contribution of WW to the COD T of the mixture is practically negligibleat least two orders of magnitude lower then COD T of FW. Similarly, the energy needed to anaerobically digest domestic WW is negligible is about one order of magnitude lower than that of FWranging between 0.05 and 0.07 kWh kg CODremoved −1 (Ge, Batstone, and Keller 2016;Kim et al 2011). Knowing that the latter range corresponds to complex AD technologies (e.g.…”

Anaerobic digestion in the kraft pulp and paper industry : Challenges and possibilities for implementation

“…Studies on activated sludge from other sectors (e.g. slaughterhouses, municipal WWT) have indicated that the degradability of WAS can be improved by an increased load of organic matter to the activated treatment where it is produced, for example, running the facility at a lower hydraulic retention time (HRT) and generating sludge of low age (Ge et al, 2016;Müller et al, 1998). Accordingly, Karlsson et al (2011) obtained methane potentials of 200 ml and 90 ml CH4/g VS (volatile solids) during batch tests of pulp and paper mill WAS with sludge ages of 7 and 10 days, respectively.…”