Statewide Implications Compliance with new phosphorus limits Sustainable Cost-effective
Bigger Picture A dead zone-causing algal bloom stained the Gulf of Mexico green in 2007. (Image from NASA/Alamy) Record-Size Dead Zone Predicted for the Gulf of Mexico Talbot, George June 25, 2013 www.al.com
Increasing wastewater volumes cause streams to be re-classified; and surface water discharge limits usually become more stringent over time. Tannehill State Park Phosphorus Discharge Limits:. 2010 Discharge Limit: 4.5 mg/l Total Phosphorus 2011 Discharge Limit: 0.3 mg/l Total Phosphorus
Typical Small Flow Aerated Wastewater Treatment Lagoon Typical Effluent: 2 mg/l Total Phosphorus Old Discharge Limit: 4.5 mg/l Total Phosphorus New Discharge Limit: 0.3 mg/l Total Phosphorus Aerated treatment lagoons are not capable of meeting a discharge limit of 0.3 mg/l Total Phosphorus.
Classic Phosphorus Removal Technology A. Physical Treatment Sand Filtration - Typically reduces Phosphorus concentration 10%. Membrane technologies Can achieve <0.1 mg/l Total Phosphorus in effluent, but is expensive to install and expensive to operate. B. Chemical Treatment Precipitation using calcium, aluminum, and iron compounds. Can achieve <0.1 mg/l, but greatly increases sludge generated during treatment, and causes additional maintenance and operating costs. Adsorption, sorption, and other experimental exotics: Iron reactive filtration systems, iron oxide tailings,. gas concrete (produced from mixtures of silica, sand, cement,. lime, water, and aluminum cake) and other materials- Can achieve <0.1 mg/l but are generally considered experimental.
Change The Outfall, Change The Discharge Limits Mudd Creek Discharge Limits Tannehill State Park.. Total Phosphorus = 0.3 mg/l Total Nitrogen (as N) = 8.0 mg/l BOD 5 = 25 mg/l TSS = 90 mg/l On-site Performance Permit Limits = Secondary Treatment Standard Total Phosphorus = None Nitrogen (as N) = None (May requires groundwater monitoring for nitrogen.) BOD 5 = 30 mg/l TSS = 30 mg/l
Acreage Is Required! (But acreage is often less expensive that phosphorus removal upgrades) 3,000 gallons/day/ acre is a reasonable estimate for most spray irrigation areas. This is approximately 0.11-inches/day/acre. Plan for expansion areas and buffer areas. (Every site is different, and must be evaluated separately.)
Spray Irrigation Can Utilize Existing NPDES Permit Ordinary commercial spray irrigation equipment can be used with secondary treated effluent.
Conventional Field Lines in Community Disposal Systems Secondary treatment of Wastewater. Multiple Zones for Redundancy and Maintenance. Adequate land area is a required. Plan for land buffers, and expansion.
Proposed Drip Irrigation Area, 6,000 gallons per day, 400-ft x 100-ft Area, Approximately 1-acre
Drip Irrigation Wastewater Disposal Suitable for steep ground and shallow soil. Secondary treatment of Wastewater. Multiple Zones for Redundancy and Maintenance. Adequate land area is a required. Plan for land buffers, and expansion.
Corridor – X Future Development of I-22 High density development at the interchange. Disposal area located away from interchange on less valuable land. More favorable discharge limits, less public opposition, less steam impact, less operator liability. Plan for land buffers, and expansion.
Approximately 500-Acres of land are needed for a one-million GPD spray irrigation wastewater facility. This could serve 4,000-homes. There are 22.9 million acres of timberland in Alabama, accounting for 68% of the total land area in the state.
New Construction: Consider Decentralized Sewer Systems with On-site Disposal Less Expensive Treatment Plant – because the discharge limits are typically less stringent. Less Expensive Sewage Collection System - because the disposal area is closer to the development. Less Public Opposition – because the discharge is not directly into a stream or river. Less Liability For the Operator – because the probability of a clean water act violation are greatly reduced.
Allen McLemore Alternative Wastewater Engineering EMAIL: firstname.lastname@example.org@altwe.com PHONE: (205) 218-8989