@article {27300,
	title = {Impact of AnMBR operating conditions on anaerobic digestion of waste activated sludge},
	journal = {Water Environment Research },
	year = {2020},
	abstract = {<section id="wer1361-sec-0001">
	<p>
		The impact of solids retention time (SRT) and hydraulic retention time (HRT) on anaerobic digestion of thickened waste activated sludge (TWAS) in a pilot-scale anaerobic membrane bioreactor (AnMBR) was compared with that achieved in conventional anaerobic digestions (CD). The AnMBR was able to successfully digest municipal TWAS at HRTs ranging from 7 to 15\&nbsp;days and SRTs ranging from 15 to 30\&nbsp;days. Increasing SRT in the AnMBR resulted in a significant improvement in COD and VS removal efficiency when compared against CD operating at the same HRT. The VS and COD destructions (35\%{\textendash}50\%) observed in the AnMBR were similar to those observed in CD operating at the same SRT but longer HRTs. Operation at elevated ratios of SRT/HRT resulted in the production of a thickened biosolid (2\%{\textendash}3\% TS). Specific methane production values for AnMBR operating at HRT-SRT ratios of 15{\textendash}30, 7{\textendash}30, and 7{\textendash}15 were 0.19, 0.19, and 0.14\&nbsp;m<sup>3</sup>\&nbsp;CH<sub>4</sub>/kg of COD fed, respectively, showing a 25\% increase in methane production with SRT. A model based upon describing hydrolysis of biodegradable solids using first-order kinetics was able to describe VS destruction as a function of SRT.
	</p>

	<p>
		\&nbsp;
	</p>

	<h3 id="wer1361-sec-0002-title">
		Practitioner points
	</h3>

	<ul>
		<li>
			The AnMBR process was able to successfully digest waste activated sludge at a shorter seven-day HRTs
		</li>
		<li>
			Operation at elevated ratios of SRT/HRT resulted in enhanced biogas and thickened biosolid (2\%{\textendash}3\% TS) production requiring reduced downstream processing
		</li>
		<li>
			The AnMBR process produces a particle-free permeate that might be suitable for side stream nutrient recovery
		</li>
		<li>
			A model developed by considering hydrolysis as a limiting process can be used to determine design SRTs.
		</li>
	</ul>

	<p>
		\&nbsp;
	</p>
</section>

<section id="wer1361-sec-0002">
	\&nbsp;
</section>
},
	author = {Wayne Parker and Martha Dagnew}
}