Zuvamesa’s main products are: juice, pulp (aka ‘cells’) and cold-pressed oils. The fibre-rich pulps are either blended back into Zuvamesa’s own juices or sold to other fruit-juice makers. Traditionally, juice-makers tend to send the any remaining biomass residues that cannot be used in the human food chain to local farms as animal feed.
However, only a fraction of the wet pulp produced by large scale juicers like Zuvamesa can be sold directly to local farmers since the daily volume of pulp generated far exceeds local capacity. Thus, the citrus industry generally sends most biomass residues to outdoor “artisanal dryers”, where the wet pulpy material is buried in the soil until it gets dehydrated, to be finally sold as animal feed. This drying method is slow and ends up producing a leachate that can contaminate the land. In addition, citrus factories tend not to get a revenue from this potentially valuable material, at best simply avoiding waste disposal costs.
Figure 1: Pellet plant at Zuvamesa’s juice factory, Valencia, Spain (Source: Zuvamesa)
An investment in an on-site ‘pellet factory’ for converting wet pulp into dry pellets as feed for cows and sheep was made. By drawing out the water from the pulpy residues, Zuvamesa’s pellet factory extends the shelf-life of the pellets for many months allowing the product to be stored until customers can be found. The pellet factory was built in 2011 at a cost of c. €9 million, with a payback of more than 10 years. It processes around 20,000 tonnes of pellets per annum. The water recovered from the pulp is re-used in the cleaning process in the pellet plant. The pellet plant burns natural gas and biogas (from the AD plant).
Zuvamesa’s R&D team continually looks for new opportunities to valorise residues. Recently, they discovered an opportunity to recover D-limonene from the wastewater by an investment in a new distillation tower in 2017. D-limonene is now sold as a solvent to the chemicals industry, and the payback is expected in about two years.
NB. The business case for D-limonene recovery is linked not to the absolute volume of wastewater processed—the investment required is proportional to the volume—but rather to the prevailing D-limonene market price which can be highly volatile. At the time Zuvamesa made the investment (in 2017), the price was very high; a couple of years later it was significantly lower.
Figure 2: Distillation tower for D-limonene recovery at Zuvamesa’s factory, Valencia, Spain (Source: Zuvamesa)
As well as the benefit of a new revenue stream, the D-limonene recovery reduces the organic load of the wastewater reducing the costs associated with treatment, so this is an added financial benefit.
(Source: Personal communications with Roger Marqués, Quality and R&D Manager, Zuvamesa)