Detecting wastewater pollution

_Lead image: Along the Suquía River in Córdoba, Argentina. From [this comment]( by @alejobonifacio, CC BY SA_ Wastewater is “used water” that’s created by households, cities, and industry. It ranges from sewage to surface runoff that can flow from roadways into storm drains. Untreated or under-treated wastewater can contain a variety of pollutants that can harm people and ecosystems when it’s released into the environment. On this page, we’re collecting information on some of the clues that might indicate wastewater pollution in the environment, and ways to investigate them. Some methods assess general water quality conditions that can correlate with wastewater pollution, while other methods can more directly signal the presence of wastewater by identifying specific pollutants. What’s on this page: Approaches to detect potential wastewater pollution Questions Activities More resources and references ## Detecting possible wastewater pollution There’s lots of information (in English and Spanish) about what to look for in the comments of this question: [What are some observable tell-tale signs of wastewater pollution?]( Some water quality characteristics you can investigate: Water color or clarity Odor Water temperature Conductivity Indicator chemicals or components _If you’ve tried any of the approaches below to detect or document wastewater, please share your experiences and [post a research note](! Also help to improve this wiki page by [editing it](!_ ### **Change in water color or clarity** Why? Solid particles, chemicals, or microscopic organisms in wastewater can give it a color or cloudy appearance. When wastewater is discharged into the environment, you might see a discolored plume in a river or a colored residue on land. _Cloudy looking stream water, [Sustainable Sanitation Alliance](, [CC BY]( _**METHODS:**_ #### **Documenting visual changes in water color or clarity** [notes:grid:wastewater-color] + [Aerial photography]( and satellite imagery _Satellite image showing discolored, cloudy water in the Gowanus Canal. From [this slideshow]( by @eymund._ #### **Documenting changes in water color/clarity with spectral imagery (might not be visible to human eyes)** + [Infrared balloon image reveals Gowanus plume](, and note [this comment]( that the plume is likely flowing sewage sludge that shows up in the near-infrared range because of the bacteria and small algae in the sludge. + Multispectral analysis of satellite images: like in the paper, “[Tracking stormwater discharge plumes and water quality of the Tijuana River with multispectral aerial imagery](,” by Svejkovsky et al. 2010. _Visible and near-infrared photos composited to reveal a plume of flowing sewage scum, originally from [this note]( by @liz._ #### **Measuring turbidity of water** Solid particles floating throughout the water (called suspended solids) increase its turbidity. Learn more about turbidity in [this research note](,+TSS+and+Clarity) from @anngneal. + The [turbidity wiki page]( has a list of sensors and other tools that enable physically measuring turbidity + [Question: How do I choose a method for monitoring turbidity?]( _Left: Secchi disk for measuring turbidity, from [this note]( by @anngneal. Right: Simple turbidity sensor prototype, from [this note]( by wmacfarl._ Activities on `turbidity` [activities:turbidity] ### **Odor** Why? Clean water should have no smell or a slightly earthy smell. Other smells could indicate under-treated wastewater. See [this comment]( from @jesseslone about odors near wastewater discharge areas and what they might indicate. _**METHODS**_ Methods and activities related to odor logging can be found here: []( Activities on `odor` [activities:odor] ### **Changes in water temperature** Why? Wastewater can be warmer than the waterbodies it’s dumped into. This includes sewage and wastewater produced from industrial processes. _**METHODS**_ #### **Thermal fishing bob** Sense changes in water temperature and display temperature differences with colored lights in the field. Take a long-exposure photograph to record the results! _A long-exposure photograph of colored lights on a thermal fishing bob towed in the Charles River, Boston. The different colors indicate differences in water temperature near a power plant, which releases heated wastewater into the river. From [this note]( by @Sara._ + About the thermal fishing bob and how to make one: []( + [Successful Thermal Fishing Bob Test: Mapping the Kendall Power Plant Thermal Plume]( Activities on `thermal-fishing-bob` [activities:thermal-fishing-bob] #### **Thermal photography** + []( + Detecting warmer water at wastewater outfalls with thermal photographs, as noted on pg. 27 of [this guide for municipalities detecting illicit discharges of wastewater]( Activities on `thermal-photography` [activities:thermal-photography] ### **Conductivity** Why? Water that has more inorganic solids dissolved in it (like salts or chemical pollutants) generally conducts electricity better---it has a higher conductivity For example, salty wastewater (brine) associated with fracking can cause a spike in water conductivity (source: [FracTracker]( Organic pollutants like oil, however, don’t generally conduct electricity well and may lower the conductivity of water. >“A failing sewage system would raise the conductivity because of the presence of chloride, phosphate, and nitrate; an oil spill would lower the conductivity.” - [US EPA]( _**METHODS**_ [ ]( Two examples: + [Coqui audible water conductivity sensor]( + [Riffle open source water monitor](, with some [ongoing questions here]( ### **Indicator chemicals or components** Why? The presence of certain chemicals or living things in water can suggest pollution from wastewater. _**METHODS**_ #### **Detecting optical brighteners** [notes:wastewater-optical-brighteners] _UV light makes a tampon exposed to optical brighteners glow brightly. In the positive control on the right, the tampon was soaked in laundry detergent. From [this note]( by @alejobonifacio._ #### **Organic waste and oxygen** Certain bacteria help to clean water by breaking down organic wastes, and they use oxygen in the process. Measuring the amount of oxygen in water and how readily it might be used can help create a picture of how much organic waste is present and how well it’s breaking down. [notes:wastewater-organic-matter] _Do-it-yourself dissolved oxygen (DO) and oxidation-reduction potential (ORP) sensor for monitoring a small wastewater treatment system. From [this note]( by @jesseslone._ There are also ways to use spectroscopy to detect organic matter (see below) #### **Bioindicators and bioassays** Using living things to help indicate or measure impacts from polluted water. Changes in the survival or growth of certain plants, animals, and microorganisms in water can indicate worsening water quality. _image to come here!_ + Sampling water and looking for microscopic organisms as living indicators (called bioindicators) of possible wastewater pollution, with the help of DIY microscopes: []( + Exposing test organisms to sampled water and measuring growth: []( + Detecting fecal bacteria (e.g., enterococci and _E. coli_) in sewage: the common water contaminants wiki page lists a [couple ways to test for fecal bacteria]( Activities on `bioindicators` [activities:bioindicators] #### **Spectrometry methods for wastewater: a grab bag** Lots of people at Public Lab are interested in spectrometry and have experience using spectrometers for environmental monitoring. We’re collecting some approaches for detecting various things related to wastewater here: + [How can we detect contaminants in water samples with a DIY spectrometer using reagents?]( + Detecting organic dyes in wastewater: [Fabrication of a Smartphone-Based Spectrophotometer and Its Application in Monitoring Concentrations of Organic Dyes](, by Koohkan et al. 2020. + Detecting rapid changes in UV/vis spectra, as an indicator for changes in incoming wastewater concentration and composition: [Real-time detection of possible harmful events using UV/vis spectrometry](, by Langergraber et al. 2006. **Some emerging research:** + Fluorescence spectrometry for detecting distinct “signatures” of organic wastewater: > “Human wastewater has distinct optical properties that are different than those typically observed in natural waters” - pg. 8, [Detection of Wastewater Contamination](, the Water Environment Federation Some preliminary results showing the fluorescence signals of sewage vs. surface water, from [Using optical sensors to detect sewage contamination in the Great Lakes]( _Different fluorescence signals from sewage and stream samples measured using a laboratory-based instrument. Public domain image from [this USGS project]( Could a DIY spectrometer or fluorometer be used for detecting optical signals of sewage with an appropriate light source for excitation? The Public Lab [Oil Testing Kit]( uses fluorescence spectrometry to detect and identify oil pollution ## Questions Questions tagged with `question:detecting-wastewater` will appear here [questions:detecting-wastewater] ## Activities Activities tagged with `activity:detecting-wastewater` will appear here [notes:activity:detecting-wastewater] ## More resources and references + [Table 5: Techniques for detection of wastewater contamination, pros and cons of each method, and relative cost](, pg. 12, from the Water Environment Federation + Koohkan R., Kaykhaii M., Sasani M., and Paull B. 2020. Fabrication of a Smartphone-Based Spectrophotometer and Its Application in Monitoring Concentrations of Organic Dyes. _ACS Omega_, 5: 31450-31455. [LINK here]( ...

Notes on detecting-wastewater by alejobonifacio