Frequently Asked Questions
How long will they last?
Why are VSB and RB systems considered "low cost" relative to conventional technology?
Do they work in cold climates?
Do they smell?
Are there valid concerns with using chlorine in wastewater treatment?
Can VSBs eliminate the use of Chlorine?
What are the challenges with using this technology?
Why is something so ideal not sought after?
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How long will they last?
The permeability (Darcy's k) of the growth media is always designed to have a k value that is at least 100 times greater than the long term acceptance rate (LTAR) that develops with the formation of a biological scum layer. As an example, NEWS would expect a coarse sand with a k value of 50 m/day to partially clog at a rate of 0.5m/day within the first several years of operation. From that point on, the growth media will continue to process and treat wastewater for many decades. Because the sand, gravel, liner, and PVC plumbing used are virtually non-destructible, there is no finite life to this technology. Logically, physical or chemical abuse, overloading, or the introduction of solids or toxic substances could destroy proper operational performance very quickly.
Why are VSB and RB systems considered "low cost" relative to conventional technology?
Properly designed, constructed, and operated, VSBs and RBs will provide highly effective waste stream purification in a system that requires virtually no energy input, needs little maintenance, uses almost no manual labor, and can be constructed at a fraction of the cost of conventional treatment plants. In contrast, conventional treatment plants generally use large amounts of electricity, require considerable maintenance, chemicals, and labor, and often have considerably higher construction costs.
Do they work in cold climates?
Yes. Even though snow cover and freezing can occur at the surface, VSBs and RBs do not freeze. Plant root and bacterial
metabolism do slow down during winter months, but NEWS compensates for this natural change by increasing the design
area by about 25%.
Do they smell?
No. These systems are designed for sub-surface flow and operate
odor free. All of the net biological processes involved are typically
aerobic. Providing that the system does not turn anaerobic from
overloading, there is no reason to expect anaerobic odors will ever
develop.
Are there valid concerns with using chlorine in wastewater treatment?
Yes. Chlorine in our rivers produces Trihalomethanes (THMs) which are linked to cancer. Two-thirds of our drinking water comes from rivers, therefore the discharge of chlorinated effluent into our rivers raises serious health concerns.
Can VSBs eliminate the use of Chlorine?
Yes. Ultra Violet Light is a better disinfecting method than chlorine, but it is rarely used because it can be expensive when the effluent is of poor quality. If the effluent has floating solids in it, the UV needs longer contact time, and therefore costs more. In place of a new VSB system, any existing plant could simply build a small VSB system to remove the solids and then use UV for disinfection. VSB systems produce high quality effluent and often only need disinfection for water intended for drinking. The plant roots put out exudes which kill fecal coliforms in the wastewater.
What are the challenges with using this technology?
The first challenge with VSB and RB technology is that they require more land area than conventional wastewater treatment. Despite this, there are ways to decrease the footprint of these systems. NEWS has constructed layered systems where a leach field was placed directly under one of the VSBs. This tecnique reduces the footprint of the system as well as recharges the water table. With the increasing population and additional water use, freshwater is being extracted, used once, chlorinated, and discharged reaching the ocean in approximately 3 days. This is a linear approach to the management of our fresh water resources, which will become more problematic as we continue increasing extraction and use. The second challenge we face is working with those who are not open to different methods and technology. VSBs and RBs are reliable technology that NEWS has offered for many decades and strives to continually enhance for the benefit of all.
Why is something so ideal not sought after?
This technology typically costs 50- 75% less to construct, 75- 90%
less to operate and maintain, and it produces an effluent typically
75-90% cleaner than conventional facilities. Unfortunately, engineers have little experience with plant growth and their use for treatment. For this reason, conventional concrete and steel
facilities were the typical technology of choice during the Construction Grants Program of the U.S.A.-E.P.A. With that program now ended, and with government grants for wastewater treatment depleted, municipalities are now faced with paying the construction, maintenance, and operational expenses of their systems.
What can I do?
Get involved. Do not automatically assume that the E.P.A. and State Regulators are implementing the least expensive, sustainable, or environmentally friendly practices. Wastewater treatment is not everybody's priority. If you live in a town or city, all the wastewater goes to a treatment facility and you pay to run, maintain, staff, and upgrade it. Are your tax dollars supporting sustainable technology that improves the quality of your fresh water, reduces the carbon footprint, recycles water, and costs less? Ask your governor, ask your town supervisor, ask your legislative representative, and get involved.
