Fig 1. Typical source of influent.

Influent running to a waste water treatment plant, consist of municipal and or commercial waste water that has been used by a consumer. The waste water treatment plant located in Arcata, California is designed to treat municipal and commercial effluent from the roughly 16,000 residence of Arcata.[1]

Municipal or domestic waste water can be classified as any water that is used in the home. This includes toilets, sinks, washing machines and any other devices you would use in your house that produce waste water. Typical sources of municipal waste water can be shown in Figures 1 through 3. Waste water is typically 99% water by mass and is referred to as influent when it enters the waste water treatment facility[1].

Commercial or industrial waste water consist of a variety of waste water pollutants. Locations such as restaurants, farms, manufacturing businesses, saw mills are all examples of commercial or industrial waste water.

Measurable Chemicals[edit | edit source]

Fig 2. Typical source of influent. Picture taken by Jordan Grant.

There are many measurable chemicals that can be found in waste water. Waste water consists of many components that need to be treated before the water is released back into the environment. These components can prove to be harmful to the environment and also to human health. The most monitored and treated of these chemicals include:

  • TSS- Total suspended solids are the total dry weight of matter that have been measured from a specific mass of water that has been pored through a pre weighed filter to determine the weight of suspended solids in that sample.[2] The measurement of total suspended solids is an important measurement because heavy metals, polycyclic aromatic hydrocarbons (PAHs), phosphorus and organic compounds are absorbed on these particles[2]. Therefore high levels of TSS could lead to elevated levels of heavy metals, PAHs and other compounds.
  • BOD- Biochemical Oxygen Demand, is a quantification of organic matter present by indirectly measuring the amount of oxygen consumed.[2] This test is important because if BOD levels are high the amount of oxygen in the water is low, thus creating a oxygen deficient environment where fish and plants will have a harder time surviving. Typical BOD levels for a pristine water source are around 1 mg/L, while untreated sewage has an average BOD value of 600 mg/L.
  • TKN- Total Kjeldahl Nitrogen, is a way to measure the total organic and ammonia nitrogen in the waste water. TKN is an important test because if nitrogen levels are high, the water source is more likely to produce high levels of algae. High levels of algae create algae blooms, which reduce sunlight penetration under the surface of the water, thus creating an environment less suitable for plant life.

Non Measured Chemicals[edit | edit source]

There are many other chemicals that are not normally treated in waste water. The high cost of treating the following chemicals is the primary reason why they are usually not treated. Chemicals such as:

  • Medication- pain, estrogen,b lood pressure and any other pharmaceuticals people take at home will show up in waste water. Medications such as estrogen, usually used in hormone treatment, can interfere with or modify an organisms natural hormone process and has been linked to abnormalities and impaired reproductive performance in some species. [3] Sedatives can effect or modify central nervous system activity. Other medications, such as antibiotics, that are disposed of by flushing or putting them down the drain can cause anti biotic resistant strains of bacteria.[4]
  • Illegal drugs- drugs are no different from medication, if the substance goes through your body it will end up in traceable amounts in your waste.

Where it comes from[edit | edit source]

There are many sources that contribute to the waste water flowing into the Arcata marsh. Some of the larger contributing sources consist of municipal and industrial waste water from the town of Arcata.[3]

Fig 3 typical source of influent open source photo

The average daily water use per person in the United States is roughly 159 gallons per day[5]. Thus, the 16,000 residents in Arcata add an average of 2.5 million gallons of water a day to the influent into the Arcata Wastewater Treatment Plant. To a lesser extent, ground water intrusion from leaky sewer pipes add to the waste water flow.[4]

References[edit | edit source]

  1. Gearheart & Higley.(1993). Constructed wetlands for water quality improvement. Boca Raton, FL.
  2. 2.0 2.1 Olivia, Moran, Joseph Morgan, Michael D.& Wiersma, James H. (1980). Introduction to Environmental Science (2nd ed.). W.H. Freeman and Company, New York, NY.
  3. R. Gearheart, Klopp,and G. Allen (1989). Constructed Wetlands for waste water treatment, Chelsea,MI.
  4. Brad Finney, Personal Communication,10/28/2008.
FA info icon.svgAngle down icon.svgPage data
Authors John Hackett
License CC-BY-SA-3.0
Language English (en)
Related 0 subpages, 5 pages link here
Aliases Arcata marsh headworks, Arcata marsh influent
Impact 582 page views
Created October 16, 2008 by John Hackett
Modified June 8, 2023 by Felipe Schenone
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