A panel of New York officials and industry experts on Tuesday discussed the basics of anaerobic digestion and the repurposing of wastewater treatment as a way to recover water resources and harvest renewable natural gases to help power the process.

The New York State Climate Action Council (CAC) Waste Advisory Panel met Jan. 5 for the third time since its founding in November.

“There are so many cross-cutting issues; whether it’s transportation, local land use, local government, large-scale versus small-scale … the key is to keep focusing on the methane emissions reductions, and the hard part is going to be quantifying all of these things,” said Department of Environmental Conservation (DEC) Deputy Commissioner Martin Brand, who chairs the panel.

The DEC last month finalized the regulations to reduce greenhouse gas emissions, the first regulatory requirement of the Climate Leadership and Community Protection Act (CLCPA). The state in October completed its public hearing process on the proposed (Part 496) emissions limits. (See New York Holds Final CLCPA Emissions Hearings.)

European Experience

George Bevington, senior project manager at construction engineering firm Barton and Loguidice, outlined the process of anaerobic digestion, which he said uses “organisms from the primordial ooze” to break down organic compounds.

Even a septic tank in the countryside is an anaerobic environment, but industrial-scale operations are much more controlled within a set range of temperature and acidity levels.

“Never look at a methanogen cross-eyed because they’re very sensitive and everything has to be perfect,” Bevington said.

Germany covers about triple the area geographically as New York but has 6,000 anaerobic digestors (ADs) compared to an estimated 200 in the Empire State, “so the technology basically starts out in Europe and then comes here because they are much more densely populated,” Bevington said.

Casella Waste Systems CEO John Casella said the existing ADs are not able to handle organics.

“When we talk generally about handling organics, that’s a misnomer,” Casella said. “We need high-quality, high-quantity materials. One of the reasons why the de-packaging is going to be successful is that you’re going to be able to have that slurry supply where you’ve separated the packaging, the plastic and the other materials from that stream that could then go to a digestor. But to change culturally where we are right now to have a stream of organic directly to an AD would be pretty difficult.”

Bevington said a simple look at recycling bins in the U.S. will show a 10% error rate in sorting, “but if you have that rate going into an AD plant, they will tell the hauler they don’t want their product anymore.”

The 22-member CAC is working toward a fall 2021 target for completing a scoping plan for achieving the state’s energy and climate goals under the CLCPA, which mandates switching to 100% zero-emission electricity by 2040 and reducing GHG emissions to 85% below 1990 levels by 2050.

Rethinking Wastewater

Jane Gajwani, director of energy and resource recovery programs for the New York City Department of Environmental Protection, reported on the wastewater subgroup, consisting mainly of her and Bevington working with staff from the New York State Energy Research and Development Authority (NYSERDA) and the DEC.

One task was to support the transformation of wastewater treatment into water resource recovery, “and we feel this is a really important goal,” Gajwani said. “It’s something that the wastewater industry rebranded itself as a few years ago, but it’s not an instantaneous change. You can’t just snap your fingers, but it really does acknowledge the potential within wastewater in trying to rethink how we go about treating water to create a circular economy.”

The idea is to extract the full range of resources contained in wastewater as renewable bioproducts, displacing fossil fuel-based alternatives while minimizing GHG emissions, she said.

This requires maximizing recovery of the embedded energy and resources conveyed in wastewater; implementing systems to minimize fugitive methane and nitrous oxide emissions associated with wastewater; leveraging existing wastewater infrastructure to meet rising demand for organic management and co-digestion; recovering digestate and biosolids for beneficial use, leading to a significant reduction in the landfilling of these resources that contribute to methane emissions from those landfills. It also means distributing bioproducts and bioenergy that benefit communities, sequestering carbon and reducing GHG emissions throughout New York.

“That’s a lot to talk about, and the first piece we tackled as a group was the minimizing of fugitive emissions,” Gajwani said. “Wastewater in general has fugitive emissions associated with it of both methane and nitrous oxide, so the first thing is whether or not we should have reduction goals. We’re trying to figure out realistically what we can obtain by 2030 and by 2050. It’s actually a little bit easier for us to figure out how to reduce emissions of methane — we have our arms around this — than nitrous oxide, which we’re in the middle of studying.”

A few policies came to the forefront, such as comprehensive and continuous active monitoring for fugitive emissions, with full regulatory and financial implications; training of DEC inspectors to assess such emissions, which would not carve a regulatory change; and to urge conversion of home septic systems to sewer systems where feasible in densely populated areas, especially on Long Island, she said.

One important policy is to support the installation of anaerobic digesters at wastewater treatment plants throughout the state and facilitate 100% beneficial use of recovered energy in the form of biogas and biosolids, Gajwani said.

Michelle “Tok” Oyewole of the New York City Environmental Justice Alliance reported on the local scale diversion and climate justice subgroup, which has held one meeting and is focused on green jobs at the local level and employment benefitting marginalized communities.

It’s a real emphasis on building the programs that people tend to disregard the work of, such as the Inner City Green Team and micro hauling groups and community-scale composters who just look at resources a bit more and have a bit more vision overall than the traditional waste management world, Oyewole said.