 |
|
|
Anne Arundel County Department of Health: Anne Arundel County, Maryland
|
Location: |
Anne Arundel County, Maryland |
|
Climate Zone: |
Mixed Humid |
|
Subdivision: |
N/A |
|
Builder: |
N/A (existing construction) |
Evaluation
Start Date: |
March 2002 |
|
Completion Date: |
November 2004 |
|
 Read all about it:
Results from this Field Evaluation were featured in a recent article in Precast Solutions Magazine: Super Septic Tanks.
|
|
Objectives: |
To evaluate the cost and performance (particularly in nitrogen reduction) of an on-site aerobic wastewater treatment system manufactured from a conventional septic tank fitted with plastic media, diffusers, and an air pump. |
|
General Construction Information: |
Site 1:
The aerobic treatment system consisted of a retrofitted 1,000-gallon septic tank, a blower and diffuser for oxygenation, randomly placed plastic media, two “geyser pumps” (one for recirculation, and one for pumping effluent to the drainfield), and a clarifier to separate solids from liquids.
Site 2:
The aerobic treatment system was similar to the unit at Site 1. However, it consisted of a retrofitted 500-gallon septic tank, fine bubble aerators for oxygenation, fixed “block-type” plastic media, and a single geyser pump for recirculation back to the septic tank (the drainfield was gravity fed). |
|
Significant Results: |
Site 1:
- Cost of 1,000-gallon treatment system was $2,400 plus between $1,500 and $2,500 for installation.
- Nitrogen-reducing performance did not meet expectations.
Site 2
- Cost of the 500-gallon treatment system was $1,700 plus between $1,500 and $2,500 for installation.
- Over a 12-month period, the aerobic treatment system reduced nitrogen by 76% more than the septic system alone.
- If there is a malfunction in which aeration ceases for more than a few hours, it may take a month before nitrification begins again.
|
|