Morehead City Benefits from New Enhanced Biosolids Drying Technology

摘要

Morehead City Wastewater Treatment Plant (WWTP), located in Morehead City, North Carolina(NC) wanted to transform their solids handling plant into a high quality, Class A or Class Bbiosolids facility. Morehead City staff evaluated traditional drying, lime stabilization, andevaporation to further dewater digested belt-press cake effluent in terms of which process couldoffer the best value to the City in terms of their four-point decision matrix: energy, environment,flexibility, and economics. The City selected RDP’s Hybrid Evaporator? following thedocumented success of the mobile pilot unit at seven facilities in NC, Utah, Indiana, Florida, andPennsylvania and due to its reduced energy usage, nutrient value, operational flexibility, and costof operation. This is RDP's first full scale installation of this technology.Optimizing operation, demonstrating consistency of biosolids quality, and proving viability ofbiosolids is essential to the successful implementation of a diverse biosolids management plan(BMP). Determining process capabilities for a cost-effective new alternative to traditionaldrying, quantifying the nutrient value of produced biosolids, and using tissue sampling toconfirm nutrient uptake by locally pertinent agriculture differentiates this Biosolids ApplicationDemonstration Program (Program) from other BMPs.Starting in March 2011, a 12-month demonstration project was initiated to evaluate these projectgoals. This Program determined the production capacity of the full scale unit at 15 tons of wetcake at 15 to 20 percent solids per 8 hour day. Evaporation rates currently matches those ofknown direct dryers, however continued optimization is expected to show efficiencies more inline with other indirect drying technologies. Nutrient content analyses showed unparalleledstability, with an N:P:K of 2.5:3.5:0.3, comparable to Milorganite. Initial soil and tissuesampling showed improved soil conditions, crop yield, and nutrient uptake when usingMorehead City biosolids when compared to use of standard fertilizers. Lastly this program wasable to show a 25 to 35 percent operational cost savings in using this Class A option whencompared to lime-stabilized Class B hauling options excluding any revenue from local users.