The Science of Sustainability

Do Water Pollution Tests Lead to "Dead Zones"?

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Photo Credit: Brenda Culler, ODNR Coastal Management

Photo Credit: Brenda Culler, ODNR Coastal Management

Reported by Robert McClure, InvestigateWest

Waterways across the country are beset by a disturbing pattern: Polluted water discharged from sewage treatment plants carries with it vast amounts of phosphorus and nitrogen, which are known as “nutrients.” The nutrients feed massive algae blooms. Those in turn spur the growth of microbes — teeny-tiny bugs — that suck out of the water the oxygen that’s needed by fish and other aquatic creatures. DissolvedOxygenNOAAThe result is aquatic “dead zones” like the one off the coast of Louisiana, where the Mississippi River flows into the Gulf of Mexico. At its peak last year, that lifeless oceanic zone reached the size of Connecticut. While scientists and engineers nationwide grapple with the problem, one persistent environmental engineer in Salt Lake City has been pointing out for three decades what appears to be a major failing of pollution tests performed at sewage-treatment plants across the country. If he is right, they are a major unrecognized contributor to the problem. To put it simply, Peter Maier maintains that current testing procedures account for the nutrients from humans’ solid waste, but not from nutrients in urine. The problem traces to the way waste is tested for “biochemical oxygen demand,” or BOD. So how did this come to pass? After the federal Clean Water Act was passed in 1972, about two-thirds of sewage-treatment plants were continually failing the required tests. The U.S. Environmental Protection Agency (EPA) then changed the tests. It eliminated the need to measure the amount of “biochemical oxygen demand” from nitrogen-based wastes — pee — while retaining the need to measure the same from carbon-based wastes — poop. The reason? It takes 30 days or so to measure the effects of the pee, but 10 days or less for the poop. Here’s how we explained it in an award-winning seriesby InvestigateWest and EarthFix titled “Clean Water: The Next Act.”

“The carbon-eating microbes are in full swing by the fifth day of the test. Their populations are thriving. But the nitrogen-eating bugs are just getting started, and may not get up to full speed until maybe the sixth to the eighth day, depending on conditions such as the temperature. (They do better in warmer weather.) It can take up to 30 days for those bugs to digest the urine-based waste. And this is where the science of sewage treatment parts ways with the actual methods used in the U.S., as Maier sees it… . The problem, Maier says, is that those nitrogen-eating bugs that die in the laboratory flask don’t get killed in the actual sewage-treatment plants. And those nitrogen-eating bugs keep on eating waste and requiring oxygen that comes out of the streams where the waste is dumped — at the expense of the fish and other aquatic creatures that live there. Plus, all the nitrogen that the bacteria haven’t eaten acts as a fertilizer for algae downstream from the sewage plant.”

So right now Maier contends that there are numerous examples of water bodies where sewage-treatment plants are meeting their official pollution-control limits, but are in fact continuing to contribute to the downturn in water quality.

Peter Maier

Peter Maier photo courtesy of InvestigateWest

Maier has sued the EPA and testified before Congress to get the word out — to little avail. Now his contentions are getting new currency as environmentalists push several suits against the EPA, including one that blames the agency for not controlling the nutrients in the Mississippi River basin that killed off part of the Gulf of Mexico. One reason Maier hasn’t gotten farther may be his cantankerous nature, friends say, and it also doesn’t help that he still has a thick accent from his upbringing in the Netherlands. Said ally Lowell Palm, a mechanical engineer, “Some of it’s Peter’s ‘foreign-ness’ and rather abrasive approach to those who might hold opinions different from his. And I think that caused a lot of tension.” Fortunately for Maier’s cause, the issue of nutrients is front and center in a case brought by environmentalists in federal court in New Orleans. The suit accuses the EPA of dereliction of duty for failing to control nutrient pollution that causes the Gulf of Mexico dead zone. A judge ordered the agency to respond by March 19 as to why, but the EPA won a last-minute stayfrom an appeals court.


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Category: Blog, Chemistry, Environment, Sustainable Health, Water

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Robert McClure

About the Author ()

Robert McClure is executive director of InvestigateWest, a nonprofit newsroom in Seattle specializing in the environment, public health and government accountability for the Pacific Northwest and British Columbia. A veteran newspaper reporter with a quarter of a century on the environment beat, he is a winner of the John B. Oakes Award for Distinguished Environmental Journalism and serves on the board of the Society of Environmental Journalists. Robert was named in 2013 as one of Seattle Magazine’s “most influential” people in Seattle.
  • pmaier

    By stating, "If he is right", the article suggest that the incorrect application of the BOD test, is a personal opinion, while in the past 30 years several institutions have acknowledged that the test is indeed not correctly applied. A fact that also can be verified in any engineering textbook dealing with sewage treatment or one can read in a description of the test in the Technical PDF section of
    Many, however have successfully claimed that this was not important, while the simple fact is that by using the 5-day reading of the BOD test, in stead of its full 30-day reading, EPA not only ignored 60% of the BOD pollution in sewage, but also all the nitrogenous (urine and protein) waste, now called a nutrient. The goal of the CWA was to eliminate all water pollution by 1985 and when one only addresses 40% of the pollution, as EPA did and still does, you simple do not implement the CWA as intended. The EPA refuses to correct this test, while sewage treatment plant operators claim that they can not perform the test correctly, because it would violate their permits, thereby of course blaming the EPA. The CWA is the second largest federally funded public works program and sadly failed because of this faulty applied water pollution test. This should be unacceptable, especially since much better sewage treatment (including nitrogenous waste) is available and actually would be less expensive to built and operate, compared to the conventional sewage treatment plants.

    • Optimist

      If he was right, every river in any populated area in the country would be an oxygen-depleted, stinking open sewer. The fact that they're not would suggest that the EPA got it right, somehow.

      • pmaier

        The 'if he was right' comment deals with BOD testing. By using its 5-day value, in stead of its full 30-day value, you ignore not only 60% of the BOD pollution, but also all the nitrogenous waste. Secondary treatment was supposed to be 85% treatment, so EPA only demanded 85% of 40% = 34% treatment, a far cry from the 85% promised.
        Fortunate most sewage treatment plants perform much better and river can treat sewage (as it is done by the same process as it is done in sewage treatment plants), in the past called the self purification of a river that led around 1910 to the BOD test. The issue here is why you would have regulations based on a faulty applied test and run the risk that you design a multi million sewage treatment plant based on misleading data. OR is the resistance solely based on the fear that correct testing will show that many treatment plants are designed to treat the wrong waste.That should be unacceptable.

        • Optimist

          The intent of the BOD test was NEVER to include nitrogenous oxygen demand. Nitrogen species are tracked separately as ammonia, nitrite and nitrate.

          My point remains: if the treatment plants only removed 34% of the "true" oxygen demand, the rivers would be oxygen-poor (thus stinking) lifeless open sewers. They are not, proving that the EPA met its mandate.

  • Enviro Equipment, Inc.

    Pollution from agricultural runoff has been such a serious issue to environmentalists for decades now that it boggles the mind why the EPA has never really tackled the issue up to now and is even fighting the New Orleans court-induced lawsuit tooth and nail as we speak.

    • pmaier

      How do you demand nutrient treatment in general, when nutrients in sewage is ignored?

      • Optimist

        Ever heard of biological nutrient removal (BNR)?

    • Robert McClure

      That's an excellent point. The answer is that Congress very intentionally exempted agriculture from the Clean Water Act. And today ag is the biggest water polluter in the country, as we discussed in this story:

      It's also worth noting, as pointed out by my friend Mark Schleifstein, environment reporter at Times-Picayune in New Orleans, that is it agriculture and not sewage that is the primary cause of the dead zone in the Gulf of Mexico. Those nutrients primarily are flowing off farm fields all the way up through the Mississippi Basin. Sewage plants do contribute, but the amount of nutrients they discharge are far oustripped by those coming of fertilized farm fields.

      • pmaier

        Since we have no nitrogen data from sewage treatment plants, we only have to believe what we are told. Each person will contribute 15 gram of nitrogen per day, which when not treated gets into open water and for each pound is capable of growing 20 pound of algae. We treat sewage for C-BOD, but the oxygen exertion of nitrogenous waste (initial 4.6×15= 69 gram or N-BOD) + the oxygen exertion of dead algae , is much higher than that from C-BOD. The conclussion is that if EPA indeed considers the depletion of oxygen as being the most important, it better focusses on nitrogenous waste, in stead, as it now does, on fecal waste only. I don't know how many people live in the watershed of the Mississippi and dump their waste in the river, but a rough estimate would be that 20% of the nutrient contribution comes from nitrogenous waste in sewage. The largest contributor probably is the reactive nitrogen coming from the atmosphere, as green rain, the result of the burning of fossil fuels. The main issue here is that this form of nutrient in sewage is the easiest to address, by implementing the CWA, other sources are much harder. If indeed as Mr. schleifstein claims the contribution from sewage treatment plants is minimal, why then even treat sewage at all?

      • Optimist

        Big Ag has congress in its back pocket. Now go fill up your SUV with overpriced ethanol!

  • Citizen Keen

    Are these primary or secondary sewage treatment plants? Is there a difference with tertiary or higher treatment?

    • pmaier

      The definitions used are causing major problems as the meaning of secondary treatment is that it follows primary treatment, while none, neither tertiary treatment, has any technical definition. It all started more than a cen ago when sewage was put into tanks (primary treatment) to remove the matter that would settle or or float. This was not enough and other matter had to be removed by adhering it to matter that would sink or float. This matter is also called biomass or activated sludge. This biomass can grow on stones ((called trickling or biological filter) or ac be suspended in an aeration reactor (aeration tank), after this process the biomass is settled in secondary clarifiers or final clarifiers. If there still is matter left, it is removed by tertiary treatment.
      Sewage treatment plants are feedlot operations, except in stead of growing food, we want to get rid of food. Before you start designing holding pens for the bugs, you need to know what type of food is in sewage and that can only be achieved by proper testing and is not only essential in any water quality program, but even more to design the proper treatment facilities. Many treatment plants are presently designed for the wrong waste.
      By the way primary, secondary and tertiary treatment (a sequential historical development, due to stricter regulations) also can be achieved in one aeration basin (like oxidation ditch or sequencing reactors) a lot cheaper as long as the proper conditions are maintained for the bugs necessary.

  • bhaskarmv

    The food chain is –

    nutrients cause algae to grow,

    algae are food for fish,

    so when there is more algae there should be more fish.

    Why is nutrient in water resulting in algal bloom and not fish bloom?
    No one is asking this fundamental question.

    • pmaier

      Algae will produce oxygen, when there is light, but when there is no light they will use oxygen, hence the dissolved oxygen levels will vary, what fish do not like. Also when the algae die, they become a food source for bacteria, who in turn will use oxygen, a process similar as what happens when sewage is dumped into open waters. Nature maintains certain ecological balances and you do not want to cause major imbalances, what happens when you put too much fertilizer (what is now called nutrients) in the water. And by the way, the increased presence of Asian Carp is a sign that you initially will get more fish when you have more algae, but too much algae, they and the fish will die, hence the dead zones. Actually they are not dead as nature simple start using anaerobic life to recycle the organic matter, but humans do not like this life cycle, as it also causes odors. A process that happened millions of years ago and yielded the fossil fuels we now use and is causing an imbalance in our atmosphere.

      • bhaskarmv


        Your answer is wrong.

        Life on earth started off as an anaerobic system and later moved to the aerobic system after Cyanobacteria started photosynthesis, so going back to an anaerobic system is not an answer.

        How do we maintain the aerobic system even in eutrophic water ?

        Fossil fuel came from algae and not from bacteria.

        All algae and plants respire.
        Algae and Plants can either be consumed by animals or die and decompose.

        Oxygen level of atmosphere is huge, all this has come from algae and plants. This is due to the net oxygen produced by algae and plants.

        So which algae and plants are net contributors of Oxygen? Which algae are food for fish ?

        If in nature algae do not provide all the oxygen consumed by all the aerobic bacteria, zooplankton and fish in the water, these organisms would not survive at all.

        So what exactly is wrong with eutrophic lakes ?

        • pmaier

          As far as Mother Nature is concerned, there is nothing wrong with eutrophic lakes, but we humans do not like change and prefer certain ecological balances, especially those we experienced as kids.

          • bhaskarmv

            Algae give food and oxygen to fish, but in eutrophic lakes DO declines and fish die due to algae.

            So there is something wrong.

          • pmaier

            Only when the algae die, then they do not provide oxygen and bacteria feeding of the dead algae also use oxygen, hence a declining dissolved oxygen level.

          • bhaskarmv

            Why does the algae die, why is not being consumed by fish ?

          • Optimist

            Read up on the Dead Zone in the Gulf of Mexico.

          • Optimist

            Also read up on the term eutrophication.

  • Optimist

    Sure the problem is residual N & P in the effluent. Nitrogenous oxygen demand would typically be low, especially for nitrifying plants.

    • pmaier

      EPA will set limits for ammonia for certain sensitive waters, but in nitrifying plants this ends up as nitrates and still for each pound will grow 20 pound of algae, who when they die will exert an oxygen demand. The only way to avoid this is by demanding de-nitrification. Easily when designed for a new plant, but hard to modify an existing plant.

      • Optimist

        Donno Meneer Maier,
        My sense is that few plants are designed these days for nitrification without denitrification. Denitrification provides several benefits including partial recovery of alkalinity and oxygen demand, as well as better settleability of the biomass.

        True existing plants typically have to give up some paper capacity to get denitrification, but it fairly easy to do: pull out some diffusers, add a baffle, a mixer and a return pump. And due to the better settling biomass, the real impact on capacity may even be positive…

  • Lloyd

    Now if I'm to understand this right, Maier seems to claim that the nutrients aren't being measured at all: because its being painted as though the nBOD test is the only way to measure for Nitrogen? C'mon now. How's about TKN, NO2, NO3, NOx, NH3, Reactive P, Total P. If the effluent is having an adverse effect, then the only reason could be that there are no nutrient discharge restrictions on these permits. I personally know of only one plant in the U.S. who discharges directly to the ocean without a nutrient restriction (and no BOD restriction either), and it's the 260 MGD Point Loma Wastewater Treatment Plant in San Diego. Its a primary only facility.

    Mr. Maier's issue needs to be the NPDES permit Nutrient restrictions (or lack thereof) and not the test that's run. These articles lead the uneducated ultra-environmentalists and their supporters to doubt the WW treatment industry as a whole. I take professional offense to that, as I put my best forward as well as many in this forum, and would like to see the sensational misinformed writers put to silence!

    • pmaier

      No you do not understand right. If you apply the BOD test then yshould not only apply its 5-day reading. The intent of the 5-day reading was to save time, BUT if you do that you should combine it with the TKN test or as good text books will say that the Total BOD = 1.5 x BOD5 + 4.6 x TKN, all based on the around 1910 made assumption that the BOD5 is solely from heterotrophic bacteria feeding on carbonaceous (fecal) waste, since there hardly are any autotrophic bacteria (nitrifiers) in human waste. This assumption is still made for raw sewage, although it is not the case,especially in warmer climates and in sewer systems with long retention time.
      This assumption is the reason why many sewage treatment plants are designed for the wrong waste and this also is the reason why nobody is supporting to correct this test, as correct testing on influents will show this. The only correct way to apply the BOD test is to use the C-BOD5 (or inhibited BOD, wherein a special chemical kills autotrophic bacteria) in combination with the TKN test, again in the following formula:
      Total BOD = 1.5 x C-BOD5 + 4.6 xTKN. This is the only way you will know to properly design a sewage treatment plant. The BOD test has liitle value for the daily operation of a sewage treatment plant, but its value (if correctly applied) is especially for biological process designs and how plant in fact treat its sewage.
      Enough reasons to corrct this essential test and drop the resistance to do so

  • Adrienne

    Linking Mr. Maier's decades' long quest about measuring oxygen demand from urine to the serious issues associated with dead zones is neither accurate nor insightful, and distracts from the public discourse on solving these problems. Scientific data (measurements, calculations, computer models, experiments) confirm that excessive nutrients (namely available forms of nitrogen and phosphorus) are leading to nuisance blooms of algae which are out of balance with the natural ecosystem (the fish and bugs either can't or won't consume those excess algae). The excess algae affect the oxygen cycle in two ways. The first is through photosynthesis and respiration. During the day, algae both produce oxygen (photosynthesis) and consume oxygen (respiration). The problem comes when the sun goes down and photosynthesis stops. This can result in low levels of oxygen in the water at night. The second is through decomposition. When the algae die, they become food for bacteria that can use up the dissolved oxygen in the water. Stratification compounds these issues (warmer water stays on top of cooler water preventing mixing of oxygen in the air with the water). Sediment loading is also important in this cycle as it affects the amount of light available to the algae and rooted aquatic plants. The Mississippi River Gulf of Mexico Watershed Nutrient Task Force has been studying the dead zone in the gulf since 1997. To help reduce (not eliminate) the size of the dead zone, there needs to be a 45% reduction in nitrogen and phosphorus loads to the Gulf (among other management actions). Point sources (primarily wastewater treatment plants) contribute only about 10% of the nitrogen load. Restoring the oxygen balance in the gulf has nothing to do with measuring BOD or nBOD. With a drainage area that affects 41 states, the solution becomes quite complicated and require load reductions from agriculture, municipalities (wastewater treatment and stormwater runoff) and septic tanks. It also requires fundamental changes in our landscape (think wetlands and marshes) and flood control.

    • pmaier

      What causes all these out of balances, is the simple fact that humans like to live in large urbanized communities, intentionally located along rivers to get rid of their waste. It also forces farmers to grow lots of food and bring it to the cities.
      The intent of the CWA was to stop using our rivers to treat our sewage, but because of a lack of understanding of an essential water pollution test, this did not happen and billions of public funds were wasted.
      In stead of people being upset, they now come with all types of excuses, trying to justify the fact that this essential test was and still is incorrectly used and we still do not know how sewage is treated and what the effluent waste load is on receiving waterbodies. Does not make sense to me and probably a majority of the general public, if they would know what is really going on and their money is wasted.