Aerated batch reactor saves homeowner thousands

Problem

The Clermont County (Ohio) Health Department discovered effluent surfacing from a failed drainfield and required the homeowner to enter the county’s Sewage Nuisance Abatement Remediation Plan. Step 1 includes measures property owners must take to eliminate the failure by assessing the septic tank’s structural integrity. Step 2 conserves water to reduce hydraulic loading. If both fail, successive phases add flow control, pretreatment or both. The final phase modifies or replaces the drainfield.

Solution

The contractor installed a new septic tank, then recommended an effluent pumping system to a modified mound drainfield for more than $20,000, beyond the owner’s budget. The contractor researched alternatives and chose a Saber Septic system from Advanced Wastewater Systems.

The system has a control panel, an air pump mounted outside the house, and an air diffuser and submersible pump in the septic tank. The system converts the anaerobic tank into an aerobic treatment system with programmable cycles of aeration, settling, and time-dosed discharge. The oxygen-rich effluent facilitates reduction of the biomat, allowing the drainfield to percolate again. Pressure dosing also prevents water from backing up into the tank or house.

The system met Steps 3 and 4 in a single, cost-effective package that took less than three hours to install.

Result

The system is producing effluent with less than 20 mg/l BOD and TSS, the drainfield is accepting it, and the homeowner saved thousands of dollars. 812/528-8784; www.saberseptic.com.

Alternative passive technology replaces a conventional drainfield

Problem

The owners of a two-bedroom farmhouse in Whitefield, N.H., had a noncompliant cesspool. They wanted a low-maintenance replacement that could withstand the rigors of tenants, yet would not require electrical and mechanical components or service contracts.

Solution

Larry Rexford of Wendell Rexford and Sons in Whitefield designed the 300 gpd system using Advanced Enviro-Septic (AES) combined treatment and dispersal pipes from Presby Environmental. He chose the technology for its reduction allowance from the water table and its ability to fit into tight spaces, install on slopes without extensive retaining walls, and flex around obstacles.

Treatment occurs in a perforated plastic pipe, a white Bio-Accelerator geotextile fabric along the bottom exterior surface, and a surrounding layer of plastic fiber mat and geotextile fabric. Ridges in the pipe allow effluent to flow uninterrupted around the circumference and cool the liquid to ground temperature. Skimmer tabs at each perforation retain grease and suspended solids, protecting the outer layers from clogging.

The Bio-Accelerator filters additional solids, speeds treatment, facilitates quick startups, provides more surface area for bacterial growth, promotes even distribution, and protects outer layers and receiving surfaces from clogging. The surrounding mat of coarse fibers further filters the effluent as it passes into the outer geotextile layer and grows a protected bacterial surface.

The lightweight pipe is installed in ASTM C-33 sand, which wicks liquid from the geotextile fabric while transferring air to the microorganisms. The technology provides a large bacterial surface to break down solids, while an ample air supply and fluctuating liquid levels increase bacterial efficiency.

Result

The Bureau de Normalisation du Quebec and NSF Standard 40, Class I Certified, confirmed that the system treated effluent to less than 2 mg/l TSS and CBOD and 218 CFU/100 ml fecal coliform. 800/473-5298; www.presbyenvironmental.com.

Recirculating trickle filter discharges to sensitive waters

Problem

The conventional onsite system at Offshore Systems, a year-round marine cargo-handling terminal with 40 workers on Amaknak Island, Unalaska, Alaska, had two failed drainfields and compromised septic tanks. The leaking collection system also had inflow and infiltration problems.

Amaknak Island, part of the Aleutians, separates the Northern Pacific Ocean from the Bering Sea. The environment is hostile and corrosion a major concern. The terminal is part of Dutch Harbor, the city’s port.

Solution

The facility hired Garness Engineering Group of Anchorage to design a corrosion-resistant system to produce effluent meeting secondary standards for discharge to sensitive marine waters. The engineers chose an AeroCell recirculating trickle filter from Quanics. They installed the two 5,000 gpd modules on an elevated platform inside a warehouse to protect them from the elements and reclaim valuable drainfield space.

Wastewater from a central lift station flows into two 3,000-gallon settling tanks, then to the 3,000-gallon recirculation tank with alternating duplex pumps. With an alternating motorized valve, the pump circulates liquid between the modules. Nozzles inside the units spray wastewater over foam cube media.

A gravity-flow collection system at the bottom returns treated effluent to the recirculation tank. Gate valves recirculate 80 percent of the liquid and send 20 percent through the chlorination-dechlorination system with two tablet feeders. An automatic valve controls the discharge rate to the ocean.

Result

Plastic tanks and components solved the corrosion issue. Operation and maintenance costs are minimal and the system has a small footprint. 877/782-6427; www.quanics.net.

Passive biofilter comes ready to install

Problem

An aerobic treatment unit failed on a property in Van Meter, Iowa. Lack of space and clay soils limited replacement options. The homeowner wanted a system with minimal maintenance and operating costs.

Solution

River to River Onsite Septic Solutions in Waukee, Iowa, chose the closed-bottom, pre-assembled Ecoflo unit from Premier Tech Aqua for an in-ground installation with minimal visual impact. RD McKinney Plumbing and Excavating in Waukee installed the system, the first of its kind in the state.

Wastewater from the septic tank enters the top of the polyethylene shell and runs into a bucket that tips back and forth, evenly dispersing the effluent onto distribution plates. After passing through holes in the plates, the liquid percolates down through peat moss for purification.

The treated water then disperses into an absorption bed of clean stone and natural soil downstream. If soil conditions allow, a bottomless version is available.

Result

Effluent is treated to surface discharge levels without UV disinfection, a space-saving step. Sampling is required annually. Results of third-party studies showed TSS at 3 to 6 mg/l, CBOD5 at 4 to 8 mg/l, and fecal coliform at 413 to 1,571 CFU/100 ml. 800/632-6356; www.premier techaqua.com.

Robust solution for a coffee shop

Problem

High-strength wastewater caused the premature failure of onsite systems at a coffee shop chain store in New Hampshire. The owner sought a more robust solution for a new shop in Newfields.

Solution

The designer sized the system to handle 1,000 gpd of combined sanitary and high-strength kitchen waste. The Clean Solution aerobic treatment system from Wastewater Alternatives provides secondary treatment. Kitchen waste flows into a 1,000-gallon grease trap, then to a 1,000-gallon single-chamber BioCon aerobic grease trap without media. Kitchen and sanitary flows combine in a 2,000-gallon single-chamber septic tank.

Effluent flows from the septic tank to a 2,000-gallon dual-chamber BioCon aerobic treatment tank with biological contact media, then to a 2,750-gallon triple-chamber settling tank before being pumped to a pipe-and-stone leachfield. Six small 4.5 cfm linear piston air compressors aerate the three aerobic chambers. Air bubbles keep the media in suspension and provide dissolved oxygen for biological activity.

Result

After 18 months, grab samples of septic tank effluent had levels of 930 mg/l TSS, 1,000 mg/l BOD5, 220 mg/l FOG, and a pH of 6.0. Grab samples from the final settling tank had TSS and BOD5 levels of less than 5 mg/l and 6 mg/l, a 99.5 percent reduction. FOG levels were less than 5 mg/l — a 98 percent reduction — and pH increased to 7.3. 603/783-8042; www.thecleansolution.com.

ATU resolves a problem on a confined lot

Problem

A more than 50-year-old septic system had completely biomatted the leachfield, and there was no room left on the small lot to install a replacement field. The household was also low income. Officials in the Clermont County (Ohio) Department of Health wanted a new treatment system that could solve the problem.

Solution

Hydro-Action and Green Excavating came up with a plan to donate all the time and material to the family. The designer sized the system to handle 500 gpd and chose a Hydro-Action aerobic treatment unit from Green Excavating. The Set-N-Go tank design has an anaerobic septic chamber, aerobic chamber with a clarifier cone, and a pump tank with a Salcor 3G UV disinfection unit with re-aeration. The system exceeds Ohio EPA NPDES standards, allowing Green Excavating to do direct discharge and avoid installing more leachfield chambers on an already extremely small lot.

Result

The system produces effluent with less than 15 mg/l BOD and TSS, greater than 6.0 mg/l dissolved oxygen, and fewer than 40 fecal coliform colonies per 100 ml. It meets the Ohio EPA environmental standards. 574/936-2542; www.Hydro-Action.com.

Packed-bed filter replaces a failed sand filter

Problem

The U.S. Army Corps of Engineers had to replace a failing 6,000 gpd sand filter at a recreational day-use facility in Sutton Lake, W.Va., before the summer season. The new system had to start up immediately, meet NPDES permit requirements of 30 mg/l BOD5 and TSS, and discharge directly into the lake.

Solution

The Corps chose the AdvanTex AX100 commercial treatment system from Orenco Systems. Workers installed three 5,000 gpd pre-engineered modules on top of the sand filter. The compact design of the 16- by 8- by 3.5-foot units expedited installation, minimized disruption, and reduced the overall footprint. The modules have telemetry monitoring and draw 3 kWh/1,000 gallons.

The system starts up quickly because the textile media provides a large surface for microbial attachment, producing immediate filtration TSS/BOD reduction. The microbes, permanently affixed to the media, never have to regrow if the system is idle for a time. The media allows loading rates up to 50 gpd per square foot and is easily serviced.

Result

The system produces effluent with less than 2 mg/l BOD5 and less than 7 mg/l TSS. It is discharged into Sutton Lake after UV disinfection. 800/348-9843; www.orenco.com/systems.

Aerobic packed-bed bioreactor treats high-strength wastewater

Problem

The onsite system at a wholesale meat packing plant in Homedale, Idaho, failed. The plant, a quarter-mile from the Snake River, produces 2,000 gpd of wastewater with seven times the domestic levels of BOD and nitrogen.

Solution

Material from the kill floor filters through a sand and grease trap, then into a 2,200-gallon holding tank. Domestic wastewater flows directly to three 1,500-gallon precast concrete septic tanks. The two streams converge in a poured-in-place 10,000-gallon tank with a HighStrengthFAST 9.0 fixed-activated sludge treatment unit from Bio-Microbics Inc. Two combined 1,500-gallon dose chambers with duplex pumps send the water to the one-acre drainfield.

The technology uses a hybrid submerged and attached growth process in an integrated fixed-film system that has the stability of attached growth without the need for controls to keep the media wet.

Because multiple biological, biochemical, chemical, and physical processes occur simultaneously within the aerobic packed-bed bioreactor, nitrification and denitrification projects are easier and achieve high percentage reduction rates.

Result

Sampling required by the local health department confirmed a reduction in BOD and nitrogen levels of more than 90 percent. 800/753-3278; www.biomicrobics.com. n