Introduction

Plant and process for the disposal of the nitrogen load of organic waste in zootechnical farms – foresees the development of a phytodepuration plant using microalgae to reduce the nitrogen and phosphorus load of livestock waste and anaerobic biodigestion sludge. This method makes it possible to comply with the EU Nitrates Directive using a completely biological technology instead of the chemical / physical technologies generally used.

Technical features

The current techniques used for the disposal of the nitrogen load of organic waste deriving from zootechnical breeding are: nitro-denitro, flocculation, sedimentation, stripping, photocatalysis. These technologies require long periods of stay, have high energy consumption and provide high-cost facilities. The proposed methodology could be more advantageous both in economic and environmental terms. The use of indigenous microalgae isolated from the effluents themselves is a guarantee of effectiveness in the treatment of nitrogen and ammonia-nitrogen removal. Experimental tests have shown a reduction of nitrogen load even higher than 90%. This methodology can be extended to the treatment of phytodepuration of sludge deriving from processes of anaerobic biodigestion in which the biodigestors are fed in large part by zootechnical wastewater. These microalgae convert the nitrogen absorbed by the slurry into molecules, especially proteins, with greater commercial value. They can also be used as organic soil improver for agriculture.

Possible Applications

• Production of plants for the disposal of nitrogen loading of zootechnical waste;
• Nitrogen recovery from livestock waste disposal plants.

Advantages

• Greater cost-effectiveness in the construction and management of the plant;
• Improved sustainability of the life cycle and recovery of livestock waste;
• Reduction of the environmental impact compared to the known methods.