Introduction

Treated wastewater (TWW) contains nutrients that are essential for the proper development of various crops irrigated with it, but can also have a detrimental effect on crops, soil, natural water sources and the environment in general.

There are several reasons why it is critical to optimize TWW and additional amendments (e.g. manure, sludge, synthetic fertilizers):

— Using excessive quantities is costly and wasteful.
— Leaching excess nutrients that the crops do not utilize can pollute groundwater and add additional treatment costs and health risks to drinking water supplies.
— Climate change phenomena that cause drought or storm cycles can overwhelm infiltration capacity and runoff to pollute streams and waterways.
— Phosphorus excess in diffuse or point source runoff causes eutrophication of water bodies and upsets the balance in wetlands and other valuable environmental resources.
— Current scientific knowledge, as provided in this document, enables users to balance nutrients and forecast their impact more accurately to enhance crops and their profitability.

Thus, it is very important to create a plan of the types and amounts of fertilizers that should be added to various crops, taking into account the amounts of nutrients that already exist in the TWW that is used to irrigate the crops.

The concentration of nutrients found in TWW depends, among other things, on the source of the wastewaters and on the level of treatment given to the wastewater, with concentration decreasing at each stage, in the initial, secondary, tertiary and advanced treatment stages.

The fertilization plans of the various crops should take into consideration the nutritional value found in TWW, with awareness that, along with the positive contribution of the nutrients in TWW, there are other aspects that should be considered when developing the fertilization plans, such as:

— the total amount of each nutrient applied during an irrigation season;
— synchronization between nutrient application with TWW irrigation and crop needs;
— availability of nutrients to the crops according to the chemical forms existing in TWW, in comparison with nutrient availability in inorganic fertilizers.

Understanding all these factors will contribute to reducing or eliminating the negative effects that excess nutrients can produce on soils, crops, natural water sources and the environment, adjusting or reducing the amounts of nutrients supplied to the various crops by inorganic fertilizers. The fertilization programme should also take into account nitrogen and phosphorus from other sources that crops can use, such as soil or crop residue.

BS ISO 16075-6:2023

Guidelines for treated wastewater use for irrigation projects - Fertilization

Current

Published:

31 Dec 2023