Question

With a team of scientists, you have constructed a wetland for the removal of nitrogen from wastewater. The nitrogen is predominantly present in the form of ammonium. After some time into the project you find that the ammonium levels in the water hardly go down. Determined to find the reason, you investigate. Discuss the biogeochemistry to what possibly could be (a) the reason(s) for the lack of removal of ammonium, and (b) how these problems could be remedied.

Answer 1

Wetlands act as natural filters in removing the different pollutants in the soil which can get accumulated through agricultural runoffs, waste water effluents etc.They remove pollutants in many different ways such as by transformation, absorbtion , adsorption etc.Wetlands have an advantage over other methods of nitrogen removal because in this process nitrogen or phosphorus removal happens naturally and hence it is a more cost effective way of nitrogen removal.

The major process of nitrogen removal in wetlands is the biological one which involves a large consortium of microbes found in wetlands and since this process occurs naturally by microbes it is temperature dependent.Any fluctuation in temperature and pH conditions will effect the rate of nitrogen removal because it will effect the population of ammonia-oxidizing bacteria.At very low pH and temperature conditions there efficiency is limited.Also, if the wetland becomes acidic due to low pH denitrification process is inhibited.

Therefore, it is essential for the wetlands that are designed to remove nitrogen works the most in the summer months and plants that are high in carbon content are used so that the substrate concentration of the microbes are sufficient for microbes to feed, grow and help accomplish the task of nitrogen removal.