How To Utilize Electrocoagulation For Efficient Phosphorus Removal In Wastewater
By Nick Nicholas
In this article, we will discuss what phosphorus is, the effects of elevated phosphorus levels on an ecosystem, and how innovative electrocoagulation technology can be sustainably used for effective phosphorus removal in wastewater and water sources.
What Is Phosphorus?
Phosphorus is one of the most common nutrients on the planet. It is formed naturally in nature, and can be found in abundance within mineral rock deposits, namely the apatite group.
Two minerals in this group, hydroxylapatite and fluoroapatite, are the main structures in our bones and tooth enamel. Phosphorus is also important in the functioning of DNA, RNA, and ATP within cells.
These facts make this mineral incredibly valuable in the biological development and functioning of living organisms.
Phosphorus can be used to make calcium phosphate, a nutritional supplement for animals and pure phosphorus is used to make industrial process chemicals. The most considerable use of phosphorus is in the agricultural industry.
Fertilizers for crops and gardens are rated for nitrogen, potassium, and phosphorus, which is vital in photosynthesis, how plants produce sugars for fuel.
As common as phosphorus is in living organisms and in industrial use, there are a number of ways phosphorus can enter water sources besides the erosion of rocks and sediment. They are sometimes added to process water to prevent pipe corrosion and to treat boiler water. Therefore, they can end up in drinking water, industrial wastewater and domestic wastewater streams. Runoff from farms can carry phosphate-rich fertilizers into surface waters, and these compounds can also travel through soil to groundwater sources.
However, soil affinity for phosphorus can keep it from traveling too far into groundwater supplies.
Finally, due to its presence in organic lifeforms, excrement or decaying organisms can also transfer phosphorus into water systems.
How Can Phosphorus Be Harmful?
Very high phosphorus levels can be toxic to humans and animals, causing digestive issues at the worst. The most concerning effect of phosphorus in surface waters is its effect on plant life and the domino effect that it causes to surrounding aquatic life.
Increased levels of phosphorus in an aquatic ecosystem can lead to eutrophication. This process basically speeds up the aging process of that particular ecosystem. The natural production/consumption cycle is thrown off balance by an increase in plankton and algae caused by the effects of eutrophication. This will initially increase aquatic animal populations because of the increase in food sources available.
However, if a blanket of algae and plankton covers the surface of the water, sunlight can no longer reach down to other plant or marine life.
When those plants die, bacteria will begin decomposing the organic waste and they use the oxygen in the water to do it.
Over time, the bacteria can use up all of the oxygen in the water, which will kill most aquatic lifeforms like fish, which will also need to be decomposed. Without oxygen, new bacteria will have to come forward for decomposition. These bacteria produce methane gas instead of carbon dioxide.
All of this inevitably ends with the water source turning into a swamp full of dead and decomposing organic matter.
In some cases, there is an increase in blue-green algae (cyanobacteria) that produces toxins that can cause skin irritation or liver damage to humans and also has negative health effects on wildlife.
How To Remove Phosphorus In Wastewater
To prevent these types of hazardous environmental effects, reduction of levels of phosphorus in wastewater and surface water is imperative. Removal of phosphorus in wastewater using electrocoagulation is an excellent water treatment method to do this.
In order to maximize phosphorus removal, a few variables must be optimized: pH, current density, time, and electrode material. Take a look at this study done in Egypt on the effects of several variables on the amount of phosphorus removed from water.
The results showed, that a neutral pH is optimal for higher removal rates along with a higher current density and increased reaction time.
The majority of the reduction of phosphorus in wastewater occurred within 50 minutes using optimized power consumption.
While there are caveats to using higher current densities for phosphorus removal — like increased power consumption and faster electrode corrosion — these are some of the most important considerations when optimizing an EC process for removing phosphorus from wastewater.