Question

What is meant by root zone process?

Answer 1

Hint: Root zone process is a decentralized treatment method. It is generally used in villages and remote areas. It uses locally available material and does not require any skilled labour for construction. No specific mechanical equipment is required for operation.

Complete step by step answer: The root zone or filter plant is a biological filter in which the biological treatment of wastewater takes place in the soil. The root network in the soil is composed of suitable plant species. When the wastewater flows, nutrient elements and all metals, bound to soil colloids, are respectively released to the atmosphere through the process of nitrification and denitrification. The turnover of these organic substances occurs with the assistance of a diverse, aerobic and anaerobic microbial activity in the soil. The aerobic activity is then supplied with oxygen from the plant roots as well as via the surface of the constructed system. Thus, all the aerobic activity is concentrated near the plant roots, whereas the anaerobic activity prevails some distance away from the roots. This mosaic of aerobic and anaerobic pockets in the soil provides the optimum conditions for a larger range of active microbes. Both aerobic and anaerobic groups of organisms are required for the breakdown of the wastewater constituents. In the root zone/filter system, the above mosaic structure facilitates all the processes to occur in the same soil volume. Therefore, it is a process that involves the prevention of water pollution.

Additional information: The root zone of wastewater treatment consists of the following steps:
i. Pre-treatment in a settler: It is a device that separates liquid from solid.
ii. First treatment in an anaerobic baffled reactor: It is a device that has several identical chambers through which the effluent moves from top to bottom.
iii. Second treatment in an anaerobic filter: It is a device filled with a filter material (usually cinder), through which the effluent moves from top to bottom.
iv. Third treatment in a planted gravel filter: It is a structure filled which has gravel material and is planted with water-resistant reed plants that provide oxygen to the passing effluent.

Note: Advantages of root zone process are:
 1) It achieves standard for tertiary treatment with low costs, such as no electricity, no chemicals for pH adjustment.
2) The maintenance cost is low since it involves no machinery and its maintenance.
3) Negligible attendance for operation and monitoring.
4) It has no sludge handling problem.
5) It enhances the landscape and gives the site a green appeal.