Integrated Multiproduct Facility for the Production of Chemicals, Food, and Utilities from Oranges

Optimal Integrated Plant for Biodegradable Polymer Production

An integrated facility for the production of biodegradable polymers from biomass residues has been developed. Lignocellulosic residues (sawdust), CO₂, and organic waste such as manure or sludge are the raw materials. Manure and sludge are digested to provide the nutrients needed to grow algae. Algae are used in full to oil and starch production. The oil is transesterified with methanol generated via biogas dry reforming to obtain biodiesel and glycerol. The starch is used together with glycerol and the pretreated sawdust for the production of the biodegradable polymer. A mathematical optimization approach is used to identify the best use of each resource and the optimal operation of the integrated facility for each case. 4732 kt/yr of manure or 4653 kt/yr of sludge was processed to produce 354 kt/yr of biopolymer and 84 Mgal/yr of fatty acid methyl ester, capturing 2.47 kg of CO₂ per kg of biopolymer with production costs of 0.89 and 0.95 $/kg, respectively, and an investment capital of 717 and 712 M$, respectively.

Nut Shells as Adsorbents of Pollutants: Research and Perspectives

Shells, kernels, and other wastes have been investigated by researchers as potential adsorbents for a number of pollutants like methylene blue (MB), Remazol Rot RB, acid blue 80, acid blue 324, or as raw materials for the production of activated carbons and biochars to serve the same objective. Activated carbons formed by such wastes have been found to remove different heavy metals like uranium, arsenic, and cadmium while their biochars removed others like lead and copper. Furthermore, the production of these adsorbents can be combined with additional ways of valorization of this type of waste like bio-oil or bio-gas generation or even added-value materials extraction. In this work, conducted research on the ability of pistachio, pecan, cashew nut, and castor seed shells to selectively adsorb and thus remove pollutants from synthetic wastewaters is being shown. This type of research needs to be expanded in order to incorporate competitive adsorption, adsorbents regeneration, and recovery of adsorbates and to evaluate their performance with real wastewaters, before they find their way to large scale applications for the removal of the respective compounds from natural waters and wastewaters. An appropriate life cycle assessment is also necessary for the evaluation of the environmental benefits arising from their use.

Multilayer Approach for Product Portfolio Optimization: Waste to Added-Value Products

A multistage multilayer systematic procedure has been developed for the selection of the optimal product portfolio from waste biomass as feedstock for systems involving water-energy-food nexus. It consists of a hybrid heuristic, metric-based, and optimization methodology that evaluates the economic and environmental performance of added-value products from a particular raw material. The first stage preselects the promising products. Next, a superstructure optimization problem is formulated to valorize or transform waste into the optimal set of products. The methodology has been applied within the waste to power and chemicals initiative to evaluate the best use of the biomass residue from the olive oil industry toward food, chemicals, and energy. The heuristic stage is based on the literature review to analyze the feasible products and techniques. Next, simple metrics have been developed and used to preselect products that are promising. Finally, a superstructure optimization approach is used to design the facility that processes leaves, wood chips, and olives into final products. The best technique to recover phenols from "alperujo", a wet solid waste/byproduct of the process, consists of the use of membranes, while the adsorption technique is used for the recovery of phenols from olive leaves and branches. The investment required to process waste adds up to €110.2 million for a 100 kt/yr for the olive production facility, while the profit depends on the level of integration. If the facility is attached to an olive oil production, the generated profit ranges between 14.5 MM €/yr (when the waste is purchased at prices of €249 per ton of alperujo and €6 per ton of olive leaves and branches) and 34.3 MM €/yr when the waste material is obtained for free.