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Algal turf scrubbers (ATS) and anaerobic digesters (AD), when combined, remove nutrients from eutrophic water while producing renewable energy through biogas production. Algal biomass was produced from an ATS system that used tipping buckets to introduce riverine water in pulses onto a flow-way with a mesh screen installed to facilitate algal attachment. This study was the first to determine methane (CH 4) production from AD of a micro- and macro-algae polyculture, harvested from an ATS, using lab-scale reactors under batch and semi-continuous feeding regimes. The lab-scale study was followed by a pilot-scale (7 m3) ATS-AD study, the largest scale study of biogas production from ATS-derived algae. Batch digestion of 'wet' algae (93% moisture) produced 158 ± 13 L CH 4 /kg VS, which was higher than algae with a lower moisture content (≤62% moisture). Continuing use of 'wet' algae as the substrate, the 2 L semi-continuously-fed lab system yielded a maximum CH 4 production value of 144 ± 7 L CH 4 /kg VS, with 60%–62% CH 4 in the biogas. The 7 m3 pilot-scale system produced 107 ± 15 L CH 4 /kg VS, with 66.4% CH 4 in the biogas. Scale-up calculations showed that a 1 ha ATS system could capture 8.73 kg N, 1.18 kg P, and 52.5 kg C/ha-d, with the resulting algae being used in AD to produce biogas for direct heating (2.8*108 J) or to power a 1.13 kW generator. While the total energy output from the 1 ha ATS-AD system is relatively low, energy production from the AD system is a supplemental benefit to an ATS system that captures nutrients from eutrophic water. This ATS-AD system could contribute to the overall Chesapeake Bay cleanup, especially in nutrient hot-spots, like the Baltimore Harbor, where high nutrient concentrations support high algal productivity, which would provide substrate for on-site energy production from AD. Unlabelled Image • Biomass from algal turf scrubber (ATS) that removed nutrients from eutrophic waters. • Methane production from ATS biomass was 158 L CH 4 /kg VS with 'wet' algae (TS = 7%). • Max CH 4 production in semi-continuous reactors was 144 L CH 4 /kg VS with 20-day HRT. • 7 m3 pilot-scale digester produced 107 L CH 4 /kg VS, with 66.4% CH 4 in the biogas. • Scale-up to 1 ha would remove 8.7 kg N/d, 1.18 kg P/day and produce 1.13 kW of power. [ABSTRACT FROM AUTHOR]