Water Pollution and Diatom Algae

 Some of the environmental and ecological problems the world is facing today are:

  • Sewage and Waste Water
  • Nutrient pollution of waterways (Lakes, Rivers, Estuaries, Coastal Waters and Oceans) due to sewage, fertilizer runoff, storm water runoff, etc.
  • Mass fish kills due to low Dissolved Oxygen
  • Algal blooms of Cyano bacteria, Red tides and Toxic Diatoms
  • Oil spills
  • Ocean Acidification due to increase in atmospheric Co2
  • Dead Zones in Oceans
  • Global Warming and Climate Change,
  • Food availability to feed growing populations
  • Decline in fish in the oceans

These are caused by high Co2 levels in atmosphere, high level of Nitrogen and Phosphorus in water due to increase in population and low dissolved oxygen levels in water due to bacterial or algal blooms. There is a common solution to all these – Diatom Algae.

Diatom Algae are one of the major groups of Algae found in both freshwater and oceans. 
They are at the bottom of the food chain and they contribute about 40% to 50% of the primary production (photosynthesis) in the oceans, this is about 20% to 25% of all photosynthesis on Earth.

Diatoms have a silica cell wall and cannot grow unless adequate amount of silica and micro-nutrients are available in the water. Hence they are considered difficult to grow, unlike other algae like Blue Green Algae which grow more easily. 

Diatoms are not seen accumulating in lakes and rivers, since they are consumed by zooplankton and fish. Blue Green Algae are not consumed by most zooplankton or fish and hence they accumulate and make the lakes eutrophic.

Diatoms absorb carbon dioxide and release oxygen during photosynthesis. The oxygen they release increases the dissolved oxygen level of water and thereby keeps it clean. They also consume N and P like any other plant.

All phytoplankton put together account for less than 0.5 % of all biomass of the world. 

"To put algae in a global perspective, the algae consists of less than 1% even less than 0.5% of global biomass, however this tiny biomass generates about 40% of our oxygen and removes about 40% of the total carbon dioxide. The small amount of algae in the oceans are doing a great job." (Page 33) 

The high oxygen level prevents growth of Anaerobic bacteria which produce Hydrogen Sulphide the gas that smells of rotten eggs off the sewage laden pools.

Diatoms can grow even in raw sewage and replace electric powered aerators in Wastewater Treatment Plants. Using Diatoms to treat sewage can transfer nutrients to fish biomass which would be a very sustainable and ecofriendly solution. 

The CO2 absorbed by diatoms in oceans may be sequestered in the depths of the oceans for a long time. There is also a school of thought which suggests that fish can sequester huge amounts of carbon in the form of calcium carbonate.