Thematic training material for the use of scrubber water as fertilizer has been published

Scrubber water is a N rich liquid solution recovered from waste stripping /evaporation process, mainly in the form of ammonia water. The ammonium ion in solution exists in equilibrium with unionized (free) ammonia that can volatize depending on pH and temperature. Concentrated ammonia water from stripping/evaporation process usually contains 10-15% ammonia which can be concentrated up to 20% by an extra distillation step. The product can be used directly as a fertiliser or as secondary raw product for fertiliser production.

Examples for ammonia water products available on the NUTRIMAN Farmer Platform

There is one ammonia water product from VP-Hobe which is selected in the NUTRIMAN project. The NH3-water is produced using the VP-Hobe Manure Valorisation system. The input pig manure or digestate is first separated into a solid and a liquid fraction. Separation takes place in a flotation unit and in a belt press sieve. A reverse osmosis unit processes the liquid fraction into a retentate concentrated-N/K2O product and a permeate product to be processed in the clean water production. The concentrated-N/K2O product will be further de-watered in an evaporator. The liquid passes through a falling film evaporator with mechanical vapour recompression. Heating the liquid in the evaporator causes water to evaporate. A vacuum lowers the boiling point, less energy is needed than when evaporating at normal atmospheric pressure. The ammonia in the incoming liquid is removed from the product flow by stripping and concentration into NH3-water (14% N). The evaporator further produces  a Potassium concentrate (25% DM), ammonium sulphate by scrubbing the vapour coming out of the evaporator.

Typical nutrient content and availability for plants:

The scrubber water recovered from manure or digestate by evaporation usually contains 10-20% of N in mineral form, which is directly available for plants. The NH3-water (ID:1527) is a liquid fertilizer with 14%N. It is a potential RENURE fertilizer which is processed manure fractions and has the value to replace chemical fertilizers.

Fields of application in agriculture: 

The ammonia water (ID:1527) can be applied in conventional farming with vegetables, grass, maize, grain. Application can be done using liquid manure injection systems. Low emission application techniques are compulsory to prevent ammonia volatilization. The recommended application rates depend on the crop needs and soil analyses. Currently max 170 kg N/ha as livestock manure (230-250 kg N/ha for derogation farms in NL).

Benefits for farmers:

High N liquid inorganic fertilizer derived from processed animal manure. The production and usage of RENURE fertilizers allows farmers to process their (excess) livestock manure into a RENURE fertilizer. In the Netherlands this product is a potential RENURE fertilizer which means that application will no longer be defined as livestock manure in the Nitrates Directive and its application will no longer be limited to 170 kg N/ha.

For more information:

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