CWEA Hosts Biosolids Specialty Conference in El Segundo California

Transcription

1 CWEA Hosts Biosolids Specialty Conference in El Segundo California On January 18, 2012, the California Water Environment Association (CWEA) Biosolids Committee hosted a specialty conference Biosolids: Energizing Your Gas Production. Fats Oils and Grease (FOG) and Food Waste Co-Digestion Workshop at the City of Los Angeles Hyperion Treatment Plant in El Segundo. Another session was held on January 17, 2012 at the San Francisco Public Utilities Commission in San Francisco. This one-day biosolids specialty conference, which trained 126 CWEA members and non-members, consisted of a series of technical presentations separated by an afternoon tour of the City of Los Angeles s FOG Digestion program. The program, organized by Committee Chairs Todd Jordan and Dave Bachtel, consisted of a morning technical session, a tour, and an afternoon technical session. The networking lunch held in the City s Environmental Learning Center also served as a venue for impromptu technical discussions with regional experts. A total of eight speakers gave presentations at both venues that covered a wide range of relevant topics, including the following: FOG Delivery Agreements for Digester Gas Enhancement Projects, Supply-Side Economics: Evaluation of the Potential Supply of Co-Digestion Substrates and Competition for the Resource, New Revenue Opportunities in Carbon Credits and renewable Energy Credits from organic Waste Diversion Including Food Waste Digestion, FOG Economics A Case Study, FOG Collection and Co-Digestion, FOG Facility Tour, FOG Co-Digestion Systems, and FOG Systems That Work Co-Digestion of Food Processing Waste Food Waste: Moving From There to Here CWEA Biosolids Committee Chair Todd Jordan (left), and Vice Chair Dave Bachtel (Right) Attendees on tour of City of Los Angeles FOG facilities (center), LABS Vice President Alec Mackie and Treasurer Ian Mackenzie (right) The conference began with CWEA Biosolids Committee and Conference Chair, Todd Jordan s opening remarks, which highlighted the overall goal of the training to effectively navigate

2 current regulations, economics, agreements, and the availability of FOG and Food Waste to energy your digestion process. Speaker Paul Worlie then provided an overview of three different FOG delivery models (1) open door (2) supply contract and (3) local collections contract. Paul reviewed the pros and cons of each model. For example the open door method is proven, provides revenue through tipping fees and proves a needed regional service, however this method has reliability, security, and rate constraints. Supply contracts provide a source of long term revenue, reduce the need for oversight, and reduce the risk of bad loads, however this method can lead to lower tipping fees, a reliance on a single large hauler, and political constraints. Local collections contracts have the highest potential for revenue, reduce environmental impacts, and guaranteed supply from local restaurants, however this method can lead to volume, political, and higher risks since it is an uncommon practice. CWEA Biosolids Committee Chair Todd Jordan welcomes participants to the 2012 Biosolids Specialty Conference (left), Attendees in the City of Los Angeles Environmental Learning Center (right) Speaker Michael Moore then continued the discussion with a presentation titled Regulatory FOG, that provided an overview of the critical components needed to make these systems truly sustainable. One major challenge is the number of regulatory agencies involved in these systems including: USEPA, SWRCB, CARB, RWQCB, RAPCD, CDFA, and CalRecycle. It is not always clear which regulations govern operations. For example does receiving FOG classify facilities as solid waste transfer stations or rendering plants, and Another example is that anaerobic digestion and methane use are supported by the CEC, CPUC, SWRCB and CalRecycle. But under new EPA incineration rules, systems that combust digester gas can be classified as sewage sludge incineration facilities. Renewable energy mandates have been set at 33% by However, CalRecycle s September 2009 guidance document on anaerobic digestion defines compost by temperature rather than process and includes anaerobic digesters operating in the thermophilic temperature range as compost facilities. This means that at temperatures greater than 122 degrees Fahrenheit the process would be classified as composting and subject to their regulations, whereas at temperatures less than 122 degrees Fahrenheit, as most digesters do, the process could need a transfer or processing facility permit. In July 2010 CDFA proposed rendering regulations for POTWs that include FOG and Food Waste digestion. Air districts are also involved through their emissions limits on IC engines and turbines. USEPA s final regulations for Sewage Sludge Incinerator (SSI) couldconsiders that the combustion of sewage sludge and sludge products as subject to their rules. Further since sludges and biosolids are considered a solid waste by USEPA, these SSI facilities would have to

3 meet the MACT standards. NACWA and CASA joined to convince USEPA that it was not their intention to classify all POTWs who generate power from biogas as SSIs, but USEPA has not issued clarifying language. CASA, CWCCG, Tri-TAC and POTWs are working with Air Districts (South Coast and San Joaquin specifically) to assure that pre and post combustion emission and clean up to pipeline quality are reasonable and achievable. In February 2011 CDFA modified regulations to include exemptions from rendering permits for these facilities, however in September of 2011 CDFA removed this exemption. In October 2011 CASA commented and there is broad support for inclusion of this exemption in a new revision to be out soon. CASA s position is that POTWs are effectively regulated by the SWRCB and USEPA and that additional regulatory hurdles and permits create a barrier to beneficial reuse of these resources. Speaker Paul Worlie (lt) Speaker Bob Wimmer (ctr lt) Speaker Joel Levine (ctr rt) Speaker Paul Cockrell (rt) Speaker Paul Cockrell then presented results from actual case studies. The Minden Gardnerville Sanitation District (MGSD) in Nevada operates a 2 million gallon per day (mgd) plant. MGSD has been accepting concentrated grease into their 500,000 gallon primary digester for 12 months. Digester gas is used to fuel a 200 kw engine generator. Paul reported that the economic payback is much longer than anticipated. Four years was projected by the study based on a $0.05/gallon tipping fee and $0.05/kWh net cogen savings. However, after one year of operation the payback period has now extended to over eight years. This deviation was the result of a single hauler, and increased competition for this resource. For example the local landfill pays $0.14/gallon tipping fee for this resource. As a result MGSD is no longer able to charge a tipping fee for this resource. Paul then discussed a more successful case study, OLSD. OLSD operates a 20 mgd plant. Two of the 5 digesters are fed grease. Digester gas is used to fuel two 350 kw engine generators. OLSD has contracted with a single grease hauler for a volume of 5,000 gallons per day (gpd) at a rate of $0.09/gallon tipping fee. The economic payback period for the project is 2 years with 29% of the savings due to reduced natural gas use and 71% of the savings due to tipping fees. Speaker Laura Moreno, highlighted the potential resource value of this material. For example, Americans dispose of enough food to fill the Rose Bowl every day (Bloom 2007). In total about 34 million tons of food waste was generated in This represents approximately 14% of the country s total waste stream and less than 3% of food waste was recovered for reuse and recycling in If 50% of the food waste generated each year in the U.S. was anaerobically digested, enough electricity would be generated to power over 2.5 million homes for a year. The USEPA has developed a Co-Digestion Economic Analysis Tool (CoEAT) because you have to CoEAT before you co-digest. This tool provides initial economic feasibility of co-digesting

4 food scraps and FOG materials at wastewater treatment plants (POTWs). This tool is intended for POTWs with excess capacity, but pre-existing digester are not required. It is designed for decision-makers with substantial technical expertise. CoEAT considers generation, collection, pre-processing, digestion, and disposal in the analysis. The analysis provides tons/day of food waste, biogas potential, avoided GHGs from landfills, existing excess capacity, capacity required to process all feedstock, total cost or revenue both capital and operating, and potential revenue from on-site energy generation. Speaker Dick York expanded upon the potential value of resource particularly in urban areas. The potential electricity from grease trap waste is 16 lbs/year/person (Wiltsee USEPA 1998). This translates to billion lbs/year for a population of 307 million. At 1 kw net production capability per pound or 30% efficiency when added to anaerobic digesters results in 560 net MW of new generating capacity. Water and wastewater pumping consumes about 3% of the nation s energy which is equivalent to approximately 153 GW annually. Sewage sludge digestion provides 1 kw/lb VSS destroyed and trap waste provides 4 kw/lb grease added. The anaerobic breakdown of fats is complex and requires different microorganisms at each stage, a wastewater environment supports this process which relies heavily on bio-availability for efficient operation. Speaker Bonnie Jones (lt) Speaker Dick York (ctr) Speaker Kelly Runyon (rt) Speakers Bonnie Jones and Alex Miot presented San Francisco Public Utilities Commission findings on their FOG to biodiesel project. FOG in San Francisco Sewers is a $3.5 million/year expense. In addition, the City s fleet of vehicles consumes over 5 million gallons/year of fuel. To investigate this potential resource the City has set up a demonstration facility at their Oceanside POTW. This is a high rate pure oxygen plant. Dry weather flow at this plant is 21 mgd (design) and 14 mgd (current operations). The plant operates four 750,000 gallon egg shaped digesters for mesophilic anaerobic digestion. There are two 550 kw co-generators on site. The City has leased a unit for a six month evaluation period. The design capacity is up to 10,000 gallons/day. Expected brown grease recover is up to 300 gallons/day. It is not straight forward to obtain a representative sample since the trap waste dewatering process recovery characterization involves a number of parameters including: brown grease, oil and grease in white water, and oil and grease in the interface layer. For the 6 month duration of the study, the City recovered a total of 6,487 gallons of brown grease. The City has seen an average increase of 22% in digester gas production for an average 5.4% increase in VS loading. Specifically results show: 4% total VS

5 in trap waste, 80% VS reduction of the FOG during digestion, 22 cubic feet gas produced per pound VS FOG destroyed, and 30% brown grease recovery during the dewatering process with the remaining portion sent to the digesters. The current trap waste tipping fee is $0.05/gallon and the value of brown grease is $0.29/lbs. The advantages of the process are reduced system overflows, revenue from tipping fees, increased gas production from 50% to 75% for 30,000 gallons/day, and higher BTU values from 60% to 70% methane content. The disadvantage of the process are a higher strength recycle stream, higher source of odor, higher truck traffic, and can result in messy operations. Speaker Erik Jorgensen (lt) City of Los Angeles FOG Receiving Tank (ctr) Attendees tour FOG facilities (rt) Ryan Sellman wrapped up the training with some practical design considerations and examples of successful installations. Ryan explained that design considerations are essential to avoiding historical problems. The volume of grease per day, potential tipping fee, and grease conversion to digester gas must be established for each system. In addition, digester mixing requirements, FOG holding tank mixing requirements, level of automation, FOG metering system, heating systems, and odor control schemes must be set. Primary drivers for success are capital cost and construction methods. This seminar contributed to CWEA s mission to train and disseminate technical information to wastewater professionals. Presentations have been posted on the CWEA website at: The CWEA Biosolids Committee is scheduling the next series of Biosolids specialty workshops in January 2013, and is encouraging CWEA members to get involved in the planning effort. For additional information about opportunities to contribute to the planning effort, please contact Todd Jordan, Biosolids Committee Chair at the following address: TJordan@carollo.com. Also, interested persons are encouraged to attend the annual committee meeting that will be held in April at the 2012 CWEA Annual Conference in Sacramento, California.