Reporting From the WEF Residuals & Biosolids Conference
Milwaukee sits on the edge of 20% of the world’s fresh water. As much as anywhere, it is a location defined by water. Just east of downtown, most of your 360-degree view to the horizon is the water of Lake Michigan. Here, water & wastewater engineering were pioneered. The industry most people associate with Milwaukee – beer – is all about water. But to those in biosolids management, the most famous thing here is Milorganite®, which is celebrating its 90th year in 2016.
Milorganite® was a focus of this year’s annual WEF Residuals & BiosolidsConference, and Jeff Spence of the Metropolitan Sanitation District of Milwaukee (MMSD) detailed its venerable history in the opening plenary session. In other presentations, Tom Nowicki, MMSD’s long-time lawyer, provided clear and concise advice from nine decades of biosolids recycling experience. And Jessica Nanes of MMSD reported that a most important – and challenging – aspect of Milorganite® product distribution is tracking myriad federal and state fertilizer and biosolids regulations that require complicated sampling and testing schedules using at least seven different approved laboratories to meet states’ varied requirements. In addition to the Milorganite® presentations, the sold-out conference tour was of the Milorganite® facility.
This focus on Milorganite®’s success highlighted how far biosolids product marketing has come. It’s interesting to note that the public agency, MMSD, spearheads the product marketing efforts, even though the operations and maintenance of the fertilizer plant is contracted to Veolia (www.milorganite.com includes a new video about the product’s 90-year history).
L to R: Greg Kester, biosolids expert at the CA Association of Sanitation Agencies, enjoys the conference tour of the Milorganite® production facility. Veolia and MMSD staff ran a smooth and informative WEF R & B Conference tour of the Milorganite® production facility for nearly 80 conference attendees. Fresh Milorganite®, right out of the oven.
For decades, there have been other “branded” biosolids products, supported by varying levels of marketing, such as Boston’s Bay State Fertilizer. The kinds of marketing efforts used are determined by who the customers are, and, when it comes to biosolids, most often the customers have been farmers, landscapers, turf managers, and soil blenders – not the general public. But, recently, the King County biosolids program has set a new high standard for prominent sophisticated marketing to the broad public with its “Loop” biosolids ingredient brand (loopforyoursoil.com).
Now, joining this elite group of fine product marketing to the general public is the new DC Water “Bloom” brand – the Class A biosolids from the new anaerobic digestion with thermal hydrolysis process from the Blue Plains WRRF (bloomsoil.com – see details and videos). After a careful brand-development process, DC Water is currently refining its biosolids product by researching potential blends, determining the best moisture level, and the effects of curing/aging. This year they will work with several major landscaping and soil products customers, getting their input in developing the most useful, consistent product possible before marketing the product broadly next year.
In his conference talk about DC Water’s efforts, Ron Alexander, soil amendment analyst and marketing expert, noted that the new focus on product quality and marketing requires attention to many details, including, for example, developing internal organizational culture that supports the product. “You have to convince your workers that what they are doing is no longer waste management,” he said. There was an example of this kind of organizational culture during the conference tour of the Milorganite® fertilizer plant: every employee naturally and consistently used the term “product” to describe the material being processed. (It’s been nearly a century since MMSD has just “gotten rid of” its “sludge.”)
After the initial focus on the highest quality biosolids products and marketing, most of the WEF R & B Conference got into the technical weeds on current hot topics, with three sessions on anaerobic digestion (AD), two sessions on co-digestion, one session on thermal hydrolysis, and presentations on combined heat and power (CHP) and renewable energy, including:
- explaining and predicting methane production efficiency by 1) analysis of microbial populations and 2) by applying fractal-like kinetic and other models;
- some advantages of silo-shaped digesters;
- possible AD configurations to increase biogas yield such as biological hydrolysis, recuperative digestion, and high solids AD;
- where to placethermal hydrolysis in the solids treatment system to optimize efficiencies;
- treatment of AD and thermal hydrolysis sidestreams;
- cooling sludge after thermal hydrolysis;
- lessons learned from co-digestion projects, including how to choose appropriate high strength wastes;
- impacts – and “unintended consequences” – of food waste and other hauled-in wastes (even bioplastics) on AD and solids quality;
- operating AD & CHP flexibly to meet varying grid electricity demands;
- case studies of new AD & energy systems at Kenosha, WI; San Francisco, CA (gas turbines); and Green Bay, WI (replacing incineration with AD & CHP); and
- detailed discussions of AD system maintenance, including digester cleaning.
One session focused on biosolids system planning, with case studies from the UK, Ontario, the state of Georgia – and Leominster, MA. Matt van Horne (Hazen and Sawyer) detailed the planning process for Leominster’s new installation of rotary drum thickeners. The “Pioneer Plastics City” had long relied on solids incineration at nearby Fitchburg, which shut down its incinerator in October 2012. The project included “on-site validation testing of the selected manufacturer’s equipment and a detailed sequence of construction to ensure that the facility can continue operations through the construction period. The overall project included significant demolition work to repurpose the vacuum filter dewatering room, rehabilitation of the major sludge pumping facilities, addition of an emulsion polymer storage and feed system, rehabilitation of the sludge storage tanks, and improvements to the control system.” For disposal, Leominster continues to haul solids – now thickened – off-site.
A session on thermal processes included preliminary findings of a “state of the science review” on energy recovery from thermal oxidation (incineration) of solids that is being sponsored by the Water Environment Research Foundation (WERF). Webster Hoener explained that the project is evaluating the potential for electricity generation and heat recovery from sewage sludge incinerators (SSIs), comparing solids incineration to coal in a triple-bottom-line analysis, and estimating the amount of energy that might be recovered. He noted that the advanced SSIs in St. Paul, MN have 10 years operating experience during which the energy recovery systems have successfully produced a percentage of the plant’s energy needs; for example, the main condensing turbine provides 20% of the plant’s electricity.
Another session focused on perhaps the hottest topic in biosolids recycling: microconstituents (MCs). There were seven papers from different research groups around the U. S., most of whom are just starting into this complex topic – Marquette University, MWD of Greater Chicago, Tulane University, University of Minnesota, University of Wisconsin, Virginia Tech, and a Dow Chemical/Alkylphenols & Ethoxylates Research Council team. Three of the papers focused on antibiotic resistance genes and their fate in digesters, biosolids, and soils. In a broad review of the literature, the experienced Chicago team explained that “the uptake of MCs by crops depends on the crop, soil type, and characteristics of the MCs. A review of published literature suggests that in general, the concentrations in edible tissues, and thus exposure via ingestion, was small as indicated by hazard coefficients (HQ) < 0.1 for most of the studied compounds. A general risk assessment conducted by following the USEPA’s guidelines also showed that the exposure of MCs via land application of biosolids represents a minimal risk to human health.”
The most extraordinary paper of the conference also had to do with chemicals in biosolids. It was a presentation by Jean Creech and colleagues about dealing with illegal dumping of high-strength PCBs and trichlorobenzene into Charlotte Water sewers. On February 6, 2014, Mallard Creek treatment facility operators noticed a chemical sheen entering the clarifiers. The plant was shut down and flow diverted to an equalization basin. By February 8th, all the contaminated wastewater was contained, and the plant resumed treatment of uncontaminated influent. The contaminated wastewater was treated separately, and the resulting dewatered solids tested above 50 mg/kg for PCBs, which classified them as hazardous waste under the U. S. EPA TSCA regulations. It took until October 17th – and millions of dollars – for all of the contaminated solids to be removed and transported safely to a licensed hazardous waste disposal facility. Parts of the plant still have to be decontaminated.
This surprise catastrophe was a huge test of Charlotte Water’s resiliency. Through teamwork with their contracted land applier, Synagro, the utility did what was needed. According to Creech, it helped that Charlotte Water has been ISO 14001 (Environmental Management System) certified for many years and has conducted emergency preparedness trainings. “We are ready for emergencies; we just never expected this particular kind of emergency.” She says the criminal dumper has been apprehended and may be helping the FBI investigate a larger ring of similar illegal activity, although few details are available as the investigation is ongoing.
One other key biosolids topic, nutrient recovery, was addressed by one session at the Conference, with descriptions of various developed or developing systems to take the nitrogen and/or phosphorus out of biosolids. As part of that session, John Donovan, former NEBRA Board Member and Treasurer, who is in the process of retiring from CDM Smith, presented to this conference for the last time. One of his final projects has been engineering for the Anuvia fertilizer manufacturing facility in Florida, which uses biosolids as the feedstock of organic nutrients in a new high-efficiency fertilizer product (formerly known as Vitag).
At the end of his talk, and at the WEF Residuals & Biosolids Committee meeting on the last day of the Conference, Mr. Donovan said some words of appreciation to the profession and gave some advice. Public skepticism and distrust regarding biosolids products remains the most significant issue, he said. Odors, emerging contaminants, and limited oversight and testing add to the skepticism. He recommended that the profession increase oversight of itself: choose land application sites carefully, add more testing to have confidence in your products, hire an independent overseer to check each truckload for malodors and other quality factors. He finished by thanking the Committee “for the privilege of bringing this [WEF R & B] Conference to Boston in 2000” and for all the information exchange it has provided.