Biosolids Market Analysis for a Strategic Long-Term Biosolids Management Program

Charlotte Water is the largest public water and wastewater utility in the Carolinas. Charlotte Water (CLT Water) owns and operates five major wastewater treatment plants and three water treatment plants in the City of Charlotte and greater Mecklenburg County in North Carolina, and provides clean drinking water and wastewater services to nearly 800,000 customers.In October 2013, Charlotte Water completed a “Biosolids and Residuals Masterplan”, which recommended system improvements at the McAlpine Creek Wastewater Management Facility, its largest wastewater treatment facility, with a current rated capacity of 2.8m3/s (64 mgd). The 2013 Masterplan recommended sludge processing to produce Class A, instead of its current Class B Biosolids product. The improvements recommended under the Master Plan, however, required large capital costs and investment into relatively new and rapidly advancing technologies. Charlotte Water therefore embarked on a follow-up “Biosolids Market Analysis” in order to develop a business case for selecting preferred technologies for implementation, considering advances in available technologies, while focusing on changing conditions in the regional market for biosolids beneficial reuse.In order to guarantee long-term solutions for sustainable biosolids management now and well into the future, Charlotte Water’s ultimate goal is to implement a biosolids program that guarantees a high degree of certainty, reliability, dependability, and with diverse options for reuse, all while being cost effective to rate payers.The approach undertaken for the Biosolids Market Analysis involved, firstly, identifying Class A and Class B products desirable in North Carolina and South Carolina, and within reasonable proximity to Charlotte. Specific products included in the assessment were Class B dewatered cake, two different heat-dried products generated by thermally drying digested biosolids, that is Class A pellets and Class A non-pellets, and Class A Cake produced by a thermal hydrolysis process (THP). Potential demands for each product and market were then investigated for agriculture, horticulture/landscaping, turf (sports fields, parks, etc.), retail, reclamation, and silviculture, among other sustainable outlets. Telephone and face to face interviews were conducted with market gatekeepers to define preferences and market potential. This was followed by field demonstration days to exhibit full scale application of appropriate products to potential users.Responses from the interviews and field demonstration days confirmed strong awareness and interest in beneficial reuse of biosolids products. The product characteristics desired the most for beneficial reuse included high nitrogen content and quality organic matter, low dust and odor, and ease of applying and spreading or provision of these services by the wastewater utility, especially for cake products. Cost was another theme that echoed across all target sectors, with the expectation being that CLT Water would provide the biosolids products free-of-charge. It was noted that there is currently a great supply of competing low-cost fertilizer products in the regional agriculture market, mainly poultry litter. This indicated that biosolids would need to be cost competitive to be considered against the alternative products. Generally Class A products were preferred to Class B, especially by cattle farmers, as these products have less regulatory restriction with regards to application. Specifically, Class A products do not require a permit or have a limit on frequency of application, have fewer restrictions on buffers from roads, homes and waterways, and would not require farmers to move their cattle off the field after application.Following the biosolids products assessment, the Market Analysis then proceeded to evaluate the state of the art of biosolids processing technologies, capable of producing the products identified as suitable for the markets considered. This ensured that the biosolids processing technologies selected would generate products that were consistent with current market demands. The technologies evaluated included thermo-chemical hydrolysis with lime and with and without digester enhancement, dewatered cake processing by a third party to generate fertilizers, THP (pre-anaerobic digestion, inter anaerobic digestion and post anaerobic digestion) and thermal drying. These technologies were reviewed against the baseline case of maintaining the current anaerobic digestion process that produces Class B dewatered cake.This study demonstrates the procedures and methodologies that were followed in the market analysis and subsequent technology evaluation, including risk evaluation and risk scoring to weigh non-cost factor influences on the selection process.