Wastewater Regulations - From Disease to Toxins to Nutrients to Endocrine Disrupters

Regulation of sanitary waste began with a focus on disease-causing pathogens (germs). When medical science was able to demonstrate the connection between disease and contaminated drinking water, regulatory activity focused on protecting drinking water from germs. Thousand of people died from cholera between 1830 and 1880 before the link to contaminated drinking water was discovered. Even so, the cholera epidemic of 1939 in Lexington, Kentucky, killed 1500 people in 10 days. To this day there are still occasional outbreaks of hepatitis, e-coli and dysentery from contaminated water around the country.

During the 1800's the United States changed from a population that drew its water directly out of lakes, rivers, springs and wells to an urban populations with water piped in from water treatment plants. This made protection of water sources and regulation of water treatment even more important: if the central plant delivered bad water an entire city could get sick or die. Health departments at state, county and municipal level created ever more detailed regulations to protect the public from bad drinking water. Both water treatment and wastewater discharge became more regulated.

During the mid 1900's a second focus emerged: toxins in the water supply. The most visible of these were acid rain and mercury, but many more toxic chemicals and trace metals were found in our lakes, rivers, streams and underground water supplies. Extensive efforts were made to determine the water quality in each and every supply source. Research was also done to determine how toxic various of these pollutants could be, what levels were dangerous and what harm they could cause humans.

Next came the realization that nutrients are contaminating the water supply. The problem about nutrients in water is that they promote growth of living organisms which in turn trigger an ecological chain of events that ruins the water and can create toxic condition in rivers, wells, aquifers and lakes.

Fertilizers are a large source of these nutrients but not the only source. There are also nutrients from pig and poultry farms getting into the water supply. This, for example, is blamed for much of the pollution in the Cheasapeake Bay. Further, nutrients are found in all human sanitary waste. Our bodies in the process of digestion create and eliminate nitrogen, phosphorous and potassium as byproducts.

Almost half of all the homes in our nation are on septic systems. Septic systems do not typically eliminate nitrogen, phosphate or potassium. It was always assumed that a septic system properly installed in ground that percolates would put these nutrients into the ground far enough above the groundwater for them to become part of the soil without getting into the groundwater. Now that assumption is being questioned.

Nutrients introduce into the discussion a whole new dimension, very different from the concerns about disease and toxins. Germs can be killed and also die quickly in the ground. Metal contaminants can be filetered out and chemical discharges can be banned. But nitrogen, phosphorous and potassium are not living organisms to be killed and they cannot easily be filtered. What to do about nutrients is a serious issue for both the septic industry and the wastewater treatment plants.

Enter now a fourth focus: endocrine damaging chemicals or ED's as described in the June 4, 2007 issue of Newsweek. We can expect a great deal more information about how the accumulation of trace amounts of chemicals from shampoos, cosmetics, shaving lotions, skin creams, dishwashing liquids, pesticides, flame retardants, plastics, medicines and other home-use products in the water supply combine to cause genetic damage.

It has been a long and sorrowful journey away from the good old days of plentiful safe water and no worries about what happened with our human waste. We will always have plentiful water and we will find ways to make it safe again. But it won't be cheap.

Losoncy is the president of Clean Up America, Inc., marketing a non-discharge waterless sanitation system known as the Eloo. Learn about this system at http://www.eloo.us

Introduction to Pipe Repair for Oil, Gas, Water or Wastewater

Pipe repair defects are categorized by type and severity. Different pipe repair techniques are available to repair almost any type of defect. Advanced material technologies, like Aquawrap®, can be used in many different types of repair.

When examing pipe damage, the following should be considered:

- roundness of the pipe, i.e. how close is the pipe to being circular?

- presence of cracks

- presence of leaks

- presence of dents

- size and shape of the defect

- presence of corrosion

In many cases the most adapatable and cost effective repair solution can be using composite wraps like Aquawrap®. Composite wraps can be considered temporary or permanent repairs depending on the application.

Leaking Pipes

On leak pipe repair, often Aquawrap® can be used in conjunction with sealant to provide an alternative to repair clamps. Engineering analysis must consider the cause of the leaks, because applying an external fix to the pipe might not prevent further leaks from developing. The practicality of leak repair depends heavily on the nature of the leak.

Dent Repair

Pipeline dents & gouges can be repaired by reinforcing the damaged area with layers of Aquawrap®. Information on the size of the defect should be recorded in relation to the dimensions of the pipe itself. A high strength transfer compound is required to fill any area to create a smooth surface for Aquawrap® to bond with.

Pipe Reinforcement

In situations where some amount of wall loss has been eroded from atmospheric effects, Aquawrap® can be applied externally as a pipe repair to reinforce the wall back up to acceptable levels. Layers of material can be added or subtracted to engineer the repair to desired characteristics.

CorroDefense provides consulting and advanced materials to help engineers who are responsible for repair & protection of infrastructure like pipelines, bridges, pilings and telephone poles. Clients come to us when they are: - vulnerable to corrosion & its effects - victimized by damage caused by machinery, abrasion or impacts - desperate to find alternatives to reconstruction If these are problems that plague you or someone you know, we might be able to help.

http://www.CorroDefense.com

Copyright 2005 CorroDefense, LLC.

Membrane Diffuser Solutions for Wastewater Treatment Systems

In the aeration basin of a typical wastewater treatment plant there are both organic and inorganic matter that can impair the function of fine bubble diffusers. Eventually this requires either additional energy to overcome high membrane headloss, or reducing the oxygen mass transfer to the process.

The rate and type of fouling depends on whether the plant is treating industrial or municipal wastewater, as well as on the process. Typically diffuser types foul more rapidly in low MCRT plants such as non nitrifying conventional processes than in high MCRT plants such as in nutrient removal processes like oxidation ditch, BNR and SBR.

Diffuser media which have been readily available in the market include porous types such as aluminum oxide, porcelain, ABS and Polyethylene, and non-porous types EPDM, Silicone and Polyurethane.

Most diffuser manufacturers have taken a targeted rather than blanket approach to diffuser fouling problems. For example, in a dairy WWTP, it is expected that there will be significant calcium fouling, therefore it is common to use a flexible membrane diffuser rather than a hard porous type which may prove more difficult to keep clean.

In some cases manufacturers have recommended lower roughness coefficient materials such as PU rather than EPDM in such applications to reduce surface adhesion of calcium, gypsum, and silicas to the membrane. However, there have always been trade-offs in the selection of a diffuser media other than porous types or EPDM. For example PU and Silicone formulations that have been used often have a relatively high headloss and lower SOTE than EPDM. Silicone is also prone to tear propagation, add most PU is resistant to only 40 C. Only EPDM provides desirable physical properties and bubble sizes consistent with high SOTE. It should be noted that any result above 7% SOTE/m is considered high, and these tests were conducted at a diffuser submergence of 4.7m.

PTFE layered EPDM membranes were introduced in late 2004 and were installed throughout the course of 2005 in two dairies, one paper mill, one post aeration basin, a brewery, a landfill leachate treatment plant, and a number of municipal sewage treatment plants. In most of the cases, PTFE layered EPDM was selected due to the failure of previous technologies to avoid fouling to a sufficient degree that the plant could operate efficiently.

Rosso and Stenstrom (in their paper Economics of Fine Pore Diffuser Aging) have empirically studied the extent of fouling and cleaning intervals of various diffuser media in a wide array of municipal sewage treatment plants and have found that aF rates between cleanings of membranes even in municipal plants are much greater than common perception, dropping from an average alpha in a low MCRT plant of 0.50 to less than 0.40 after up to 2 years and stabilizing to less than 0.35 thereafter. At this time specifically in low MCRT plants they have found that the difference in aF between porous and non-porous fine bubble media do not vary significantly.

Stamford Scientific has recorded case studies where diffusers did not require cleaning, however, it was the operator's curiosity to look at the diffusers that drove them to drain the tanks and inspect them. In both cases, the surface bubble pattern was consistent with new and clean diffusers, the dissolved oxygen concentrations had not changed from new, and the diffuser headloss appeared not to have changed significantly.

There are tests and evidence that shows little to no change in a between a new PTFE and an aged PTFE membrane in a typical municipal plant setting. This also includes evidence that there is little to no change in DP, with the help of independent research and the addition of further empirical examples. If this can be proven, wastewater plants of all sorts that install PTFE layered membranes will be looking at energy savings over the operating life of the plant of 30 to 40% with the added benefit of reduced maintenance and perhaps less frequent replacement requirements.

Information on empirical test results from wastewater systems found at Stamford Scientific Inc. who specialize in membrane diffuser, aeration systems, and wastewater treatment systems. Sewage treatment systems include other diffuser products like fine bubble diffuser and disc diffusers.