1. Applicability to Developing Nations Cholera outbreaks are prevalent in developing nations that use domestic wastewater for irrigation. PAA is effective in the inactivation of Vibrio Cholera species and is capable of reducing fecal coliform levels below the World Health Organization (WHO) guideline of 1000 CFU/100 ml. PAA is a General Purpose Farm Disinfectant Commercially Available in Low Strength 5 % Solution Farm Economics A Monte Carlo simulation was performed to forecast the Net Present Value (NPV) per acre of lettuce production using a discounted cash flow analysis and uniform probability distributions for construction costs, discount rate, amortization rate, and annual chemical costs. Base Return to Land and Risk: $243.90 per Acre 975 Cartons per Acre at $6.60 per Carton Present Worth of Construction $89,256 +/- $2,137 99 % Probability of Non-negative NPV per Acre 10 yr Amortization of Construction Costs 5.75 % ($0.38) Increase in Carton Price $370 per Acre Additional Gross Revenue Reduction of Fecal Bacterial Load in Produce Irrigation Water Using Peroxyacetic Acid Task 14 Ashley Hendricks and Sarah Loughney Experimental Protocol PAA disinfection experiments were performed on laboratory synthetic test water spiked with Escherichia coli K-12 and on settled Rio Grande River water spiked with Escherichia coli K-12 and domestic wastewater influent. Initial Escherichia coli K-12 spike: 10 5 to 10 6 CFU/100 ml PAA Dose and Contact Time: 2 to 10 mg/L and 15 to 120 min, respectively Hach Chemical Company Method 10029: Membrane Filtration and Plate Count M ColiBlue ® 24 Media with 24 hr Incubation at 35°C Problem Statement and Objectives EnviroTech Systems (ETS) was asked to develop and demonstrate a cost effective and innovative way to reduce the bacterial load in irrigation water used for fresh fruit and vegetable production on a 40 acre farm located in southern New Mexico. Primary Objective: 2.2 CFU/100 ml as Fecal Coliform in disinfected water Secondary Objective: Minimize the impact on land use and farm economics Selected Disinfection Method The ETS design team developed a screening matrix format to evaluate various physical and chemical disinfection technologies based on comparative and performance-related issues and operational and maintenance aspects using an extensive literature review and vendor-supplied information. Peroxyacetic Acid (PAA) was selected as the most viable candidate. High Disinfection Efficiency and Fast Kinetics Technology Commercially Available and Used for Wastewater Disinfection Low Capital Investment and Low Labor Requirements Low Impact on Land Use Biodegradable Residuals with No Disinfection By-product Formation Full Scale Design Based on New Mexico Cooperative Extension Service irrigation recommendations for production of fall and spring lettuce and using a 4 hour per day watering cycle and a 4 day rotation per 10 acre quadrant, a 2000 gpm flow rate was selected for full scale design. Regulations PAA is an approved anti-microbial agent for use on fresh fruits and vegetables (FFDCA 21 CFR § 178) and is a registered pesticide (FIFRA 40 CFR § 152). The proposed disinfection process is also governed by a variety of other regulations. Worker Health and Safety-OSHA (29 CFR § 1910) Emergency Planning and Preparedness and Community Right to Know Chemical Reporting-EPCRA (40 CFR § 355 and 370) Hazardous Waste Generator Requirements and Farm Pesticide Exemption- RCRA (40 CFR § 262 and 272) Emergency Response Cleanup Operations-CERCLA (40 CFR § 302) Hazardous Material Shipping Requirements-HMTUSA (49 CFR § 173) References Baldry, M., et al., “Effluent Disinfection in Warm Climates with Peracetic Acid” Water Science Technology. 31.5-6 (1995): 161-164. Lefevre, F., et al., “Peracetic Acid Disinfection of Secondary Effluents Discharged Off Coastal Seawater”. Water Science Technology. 25.12 (1992): 155-164. Wagner, M., et al., “Disinfection of Wastewater by Hydrogen Peroxide or Peracetic Acid”. Water Environment Research. 74.1 (2002): 33-50. Waste-Management Education and Research Consortium 2003 Design Contest Experimental Results Observed bacterial die-off was modeled using Chick-Watson disinfection kinetics as a function of PAA dose and contact time. Log (N/N o ) = -1.48 C o 0.74 T R 2 = 0.72 Inactivation Coefficient and Dilution Constant Comparable to Lefevre et al. Disinfection Kinetic Rate Increased with Increased PAA Dose Range: 5.2 to 15.2 per hr (base e) for Total Coliform Lower Kinetic Rates Observed for Fecal Coliform Die-off No Observable Difference in Total Coliform Die-off between settled Rio Grande River Water and Laboratory Synthetic Test Water at 2 mg/L PAA Earthen Sedimentation Basins ($26,220)Liquid Feeders ($7,880) Detention Time2 hr @ 1000 gpmTypeSimplex Diaphragm Surface Overflow Rate280 gpd/ft 2 Capacity5 gph TSS Removal50 %PAA Dose10 mg/L (max) Concrete Contact Chambers ($42,459)Storage Tank ($12,697) Serpentine Channels10TypeDouble-wall 316L SS Detention Time1 hr @ 1000 gpmCapacity2000 gal