Notes from 2017 WEF RBC
This year’s WEF Residuals & Biosolids Conference (RBC) was held in Seattle, WA in early April. Northwest Biosolids was co-sponsor and local host of the conference, ensuring some clear mornings that allowed Mt. Rainier to shine on the southeast horizon and some clear visions for resource recovery through biosolids.
Like many conferences in the past several years, the 2017 RBC focused a lot on anaerobic digestion and associated topics such as co-digestion, thermal hydrolysis, and biogas cleaning and use. But it being in the Northwest, where high percentages of biosolids are recycled to soils in mature, stable, and diverse programs, there was plenty of information on land application.
In her opening session plenary, Professor Sally Brown (yes, now a full Professor!), Univ. of Washington, highlighted the growing focus on soil health and the role biosolids and other organics play (including mention of David Montgomery’s new book on regenerative farming). The “Brown Revolution” (brown referring to soil, not her, she said), involves food security, profitability for small farms (<1000 ac), carbon (C) sequestration, ecosystem resilience, and other interrelated benefits. Restorative farming and regenerating soils involves things that are being done already: no till, varied cover crops, high intensity short-term grazing, manure, composts, biosolids, char. Biosolids are part of the solution for fixing soils. “You have one of the best tools out there to create healthy soils,” Dr. Brown noted.
Big picture policy carried over from the plenary to sessions on biosolids management, facility planning, and communications. Jimmy Slaughter (Beveridge & Diamond PC) summarized recent major court decisions in favor of biosolids recycling (e.g. the Kern County case, and a decision by the PA Supreme Court). He noted also, however, a new tort lawsuit in northeast Pennsylvania, where neighbors to a farm are claiming harm in hopes of gaining a settlement from a biosolids management company. Bob O’Dette, a state regulator with long experience, described biosolids trends in Tennessee, and several engineers detailed facility plans for improved biosolids processing and products. An example was Todd Williams’ (CH2M) discussion of the new biosolids composting operation at Kodiak, AK.
It’s clear that more biosolids generators are treating biosolids processing and management like business, designing biosolids products and analyzing markets:
· DC Water is designing, blending, and testing soil amendments made with its new thermal hydrolysis Class A biosolids, to find and develop markets in Washington, DC.
· The U. S. Department of Energy staged a full session on “Energy-Positive Water Resource Recovery,” looking at research and demonstration projects aimed at assessing the potential and maximizing energy efficiency and recovery from wet waste streams through, for example, biodiesel production.
· Denver (CO) Metro is upping their charge for biosolids applications to farms to $0.15/lb of plant-available nitrogen (PAN) applied, which is about 30% of the cost of equivalent commercial fertilizer for farmers. The Metro-owned and -managed farm recoverd 25% of the resource recovery department's expenditures in 2016! The discussion is, can biosolids pricing go even higher, given the benefits they provide to farmers? This recent price increase in Denver’s program led to some complaining on the part of farmers, but no one stopped ordering biosolids; it’s still a really good deal.
As usual, many of the conference presentations got into the weeds, with numerous presentations on technical details of anaerobic digestion, co-digestion, dewatering, thermal processes, and biogas use. There was a full session on biomethane – renewable natural gas; this hot topic is getting ever more attention because it can be the most valuable use of biogas in some cases. But, in contrast to the gas clean-up required for that, another presentation stressed the simplicity of using minimally-treated biogas to generate electricity by using a new generation Stirling engine.
And gasification and pyrolysis remain one focus of biosolids energy generation efforts. A full-scale plant in Lebanon, TN is up and running, gasifying waste wood (~25 tons/day) with smaller amounts of biosolids (6 – 7 wet tons/day) and generating electricity with organic rankine cycle (ORC) engines, with a total carbon conversion efficiency of the system reported to be 90%. (This is currently the only full-scale biosolids gasification system operating in No. America.) Meanwhile, lab research continues, as it has for many years, trying to figure out the ideal temperatures and pressures for obtaining just the right balance of syngas, bio-oil, and char from biosolids, for best energy and reduced air emissions. Autocatalytic pyrolysis of biosolids looks hopeful, according to Professor Daniel Zitomer’s team at Michigan, able to produce a little net energy, at least if the biosolids are mostly dried going into the process. But full-scale testing is some time off.
As usual, much value of the conference was in the committee meetings and networking, learning about key developments in the field and what professionals are facing, for example:
· Recent changes in Washington and at U. S. EPA were reflected in discussions at the WEF RBC meeting regarding the impacts of an executive order that would shake up the renewable identification (RIN) markets, which could inadvertently affect biogas utilization projects.
· Retirements continue at a significant pace, drawing away decades of experience, such as upcoming retirements of two key leaders (Tom Granato, Dan Collins) of Chicago’s massive biosolids program. Here in New England, Charlie Tyler, legendary leader at the Deer Island Treatment Plant in Boston and in state and regional associations (e.g. NEWEA), has retired.
· Privatization of biosolids management operations and public-private partnerships continue to be explored, as reflected, for example, in recent proposal requests from several Florida cities, like Jacksonville.
· British Columbia continues its public debate of biosolids. A late-February two-day conference staged by concerned citizens and First Nations included David Lewis, formerly of U. S. EPA and a long-time critic, as well as representatives of biosolids programs of Metro Vancouver and Tacoma, WA. Development of new provincial biosolids regulations is now delayed because of upcoming elections.
· Cities in the San Francisco Bay area are collaborating on developing biosolids management options in preparation for a likely phase-out of the use of biosolids as alternative daily cover (ADC), which is a common practice there in the wetter winter months. The change is being driven by a new California law aimed at reducing methane emissions from landfills.