Photo voltaic drying consists of profiting from photo voltaic power to evaporate a part of the water within the slurry so as to scale back its quantity and facilitate its export. Due to this fact, it could be helpful to review this different in a scenario the place there’s a nutrient surplus, both alone or together with one of many different three methods (primarily based on biogas manufacturing, primarily based on physical-chemical separation and filtration, or primarily based on nitrogen removing). Determine 1 reveals a diagram of considered one of these installations and Determine 2 reveals an image of considered one of them.
This technique seeks to cut back the quantity of the slurry to facilitate its transport and export, which may be relevant in a non-surplus scenario. Due to this fact, partial evaporation (e.g. evaporation of fifty% of the water) could also be ample.
The thermal processes of focus by evaporation and drying will also be carried out by profiting from the photo voltaic power incident on a greenhouse by way of which slurry or stable fractions flow into, with the assistance of a mechanical rake system or a cell machine that breaks the floor crusts, which scale back the switch of humidity to the greenhouse ambiance. The greenhouse air have to be renewed in a managed method to keep away from saturation of humidity.
The primary limiting issue is the doable volatilization of NH3 or different compounds, so no less than the pH within the slurry have to be managed, with the addition of acid, and the emissions produced, mainly natural compounds and residual ammonia. Due to this fact, the humid air extracted from the greenhouse should go by way of a biofilter or different therapy system to maintain emissions beneath acceptable values.
The sizing of the installations must be primarily based on the incident photo voltaic radiation all year long, the relative humidity of the ambiance, and the circulation of water to evaporate, so the design must be tailored to native situations. In several checks carried out with experimental greenhouses within the situations of the Aragon and Catalonia areas in Spain, within the winter the water evaporated might be under 1 kg/m2-day, whereas in summer season it may be between 4 and 9 kg/m2-day, relying on the placement (Prenafeta-Boldú and Parera, 2020). These values can present an preliminary approximation to estimate the realm wanted for the greenhouse.