Carbonate Equilibria

Carbonate Equilibria

Carbonate Equilibria

10/14/25

“How does the interaction between carbon dioxide and water keep pH levels stable?”

Water (H2O) can absorb carbon dioxide (CO2).  Some of this CO2 will react with the H2O to form carbonic acid (H2CO3), and some carbonic acid will reversibly decompose into a hydrogen ion (H+) and bicarbonate (HCO3-), and some of the bicarbonate will further reversibly decompose into a hydrogen ion and carbonate (CO3). The more basic a specific body of water is, the more likely these decompositions will occur. At pH levels below ~6.3, carbonic acid predominates. At pH levels between 6.3 to 10.3, bicarbonate predominates. At levels above 10.3, carbonate predominates. This balance is described as the Carbonate Equilibria. The balance of these chemicals holds a massive influence over a water body’s alkalinity and potential for certain treatment methods. 

Air Stripping (Water Treatment)

Air Stripping (Water Treatment)

Air Stripping (Water Treatment)

10/13/25

“How can we use air blowers to remove volatile organic compounds from water?”

Toxic volatile organic compounds (VOCs) might seep into water during the water cycle. According to Henry’s Law, low air pressure can remove these VOCs from water. So what if we were to push water into a tower with air from a giant air blower coming from the bottom and move it down while exposing as much surface area as possible to the low-pressure air to filter out the VOCs? This is the idea behind Air Stripping, a common method for treating VOCs in human-use water. 

Image credit: https://hydroquipinc.com/

Mass Transfer

Mass Transfer

Mass Transfer

10/12/25

“How does mass move from one phase/substance to another?”

Substances in different phases or substances may come into contact with each other. This can cause the mass of a certain substance in one phase or concentration to move to another, such as through diffusion (one substance moving from a single concentration in another to uniform distribution), convection (mass transport by bulk motion of a surrounding fluid), absorption (chemical penetration of one substance into another), or distillation (separation of different components by different boiling points). This Mass Transfer is foundational to understanding how chemical engineering systems operate.

Groundwater Conservation Easements

Groundwater Conservation Easements

Groundwater Conservation Easements

10/11/25

“How can governments compensate property owners to restrict groundwater usage?”

Aquifers can deplete, and land can subside if too much groundwater is pumped. In many parts of the world, groundwater resources are controlled by private property owners. Enforcing these property owners to conserve the greater good can be difficult. One tool governments can leverage is to offer incentives to landowners, such as direct payments, credits, or tax write-offs, to conserve groundwater. One example is California’s Sustainable Groundwater Management Act to improve groundwater conservation coordination between communities and local governments. These Groundwater Conservation Easements can enable aquifer protection and sustainable land-use for regions to prosper.

Detention Time (Wastewater Treatment)

Detention Time (Wastewater Treatment)

Detention Time (Wastewater Treatment)

10/10/25

“How can we quantify the amount of time wastewater spends in a tank or basin?”

Wastewater is kept in tanks and basins as part of treatment processes. The amount of time it spends in these is given by the Detention Time, equivalent to the volume of wastewater divided by its flow rate.

Chlorine Disinfection for Water

Chlorine Disinfection for Water

Chlorine Disinfection for Drinking Water

10/09/25

“How can we use chlorine to make water safe to drink and swim?”

All sorts of pathogens harmful to human health reside in water. We need to disinfect water before we drink it. But what chemical should we use? Well, it turns out that chlorine is an incredibly useful tool. We can add chlorine in the form of chlorine gas (Cl2), sodium hypochlorite (NaOCl), and calcium hypochlorite (Ca(OCL)2) to water. The chlorine will then react with the water to form hypochlorous acid (HOCL) and hypochlorous acid (HCL). Hypochlorous acid may then dissociate into hydrogen ions (H+) and Hypochlorite ion (OCl-). The dissociation process is pH level and temperature dependent, and the HOCL and OCL- amounts are equal at pH levels of 7.5 and 20 degrees Celsius. Below a pH of 7.5, HOCL is dominant, and OCL- is dominant above 7.5. HOCL and OCL disinfect water by breaking down the cell walls and internal components of pathogens. HOCL is 80 times more effective at destroying E.coli than OCL- is. In Chlorine Disinfection for Drinking Water, there are at least some chlorine residuals left after the process ends. The amount of time and residual concentration the water is in contact with the chlorine is incredibly important for the disinfection process. Chlorine disinfection is used at a wide range of scales, from swimming pools to gargantuan treatment plants.

Alkalis

Alkalis

Alkalis

10/08/25

“What makes bases that dissolve in water so special?”

Bases in chemistry come in all forms. Some of them dissolve in water. These soluble bases, or Alkalis, are vital for helping water absorb acids. Examples of bases include sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2).

Image credit: https://www.polyestermfg.com/

Lime Softening

Lime Softening

Lime Softening

10/07/25

“How can we use lime to remove magnesium and calcium ions from water?”

Water with an overabundance of magnesium and calcium ions requires water softening to prevent soap scum buildup. One way to accomplish this is to add limewater (calcium hydroxide) to the water to raise its pH level, forcing the magnesium and calcium to precipitate out by bonding with carbonate molecules. This process, often referred to as Lime Softening, is an effective way to soften water for practical use.

Image credit: https://samcotech.com/

Dissolved Oxygen

Dissolved Oxygen

Dissolved Oxygen

10/06/25

“How do we measure the amount of oxygen in water?”

Water usually contains free, unbonded oxygen molecules. This oxygen enables marine species and bacteria to breathe and facilitates wastewater treatment reactions. The amount of oxygen in water is measured as Dissolved Oxygen in mg/L. Water’s ability to hold dissolved oxygen decreases with increased salinity and temperature.