Every year, Colombia witnesses the production of approximately 5,500 tons of starch derived from 27,000 tons of cassava roots. This process, while integral to various industries, poses environmental challenges due to the significant volumes of wastewater generated. The conventional methods of starch production not only consume substantial water resources but also result in the discharge of pollutants, impacting the local waterways. Recognizing the need for sustainable alternatives, a collaborative effort between Universidad del Valle (UV), Cali, Colombia, and the Institut français de recherche scientifique pour le développement en coopération (ORSTOM), France, supported by the European Union (EU), aims to address these environmental concerns through innovative wastewater treatment technologies.
Challenges in Cassava Starch Production
The cassava-starch extraction process involves several stages, including root washing and peeling, rasping, screening, starch sedimentation, and fermentation. Each stage contributes to the generation of wastewater with varying compositions. The traditional approach results in the discharge of approximately 13.5 tons of chemical oxygen demand (COD) per day into Colombian rivers. This poses a threat to water quality and environmental sustainability.
Wastewater from cassava starch extraction comprises two main sources: the first arises from the washing and peeling of cassava roots, containing inert material with low COD, and the second emerges during the draining of starch sedimentation tanks, carrying a high contaminating load of COD and biochemical oxygen demand (BOD). The need to address these environmental concerns prompted the initiation of a pilot project to explore alternative wastewater treatment technologies.
Innovative Solutions: Anaerobic Filter and Transfilter Technology
To combat the environmental impact of cassava starch production, a pilot project proposes the utilization of an anaerobic filter and transfilter technology. The transfilter technology, successfully tested in France with household effluents, employs a unique approach by immobilizing microorganisms on a lignocellulose support. Laboratory studies assessed the hydrodynamic characteristics of various support materials, including sugarcane bagasse, bamboo, and paja de monte (underbrush straw). Among these, paja de monte demonstrated superior characteristics, paving the way for further exploration.
The transfilter process offers a three-fold solution: purification of wastewater through filtration and digestion of organic material, production of biogas as a potential energy resource, and digestion of lignocellulose material, generating solid waste suitable for composting. This integrated approach aligns with the principles of sustainability and circular economy, ensuring that the byproducts of wastewater treatment find beneficial applications.
Feasibility and Application in Cassava-Starch Production
Colombia’s agricultural landscape, dominated by small and medium-sized agroindustries, necessitates versatile and cost-effective water treatment systems. The application of transfilter systems, particularly anaerobic processing, is currently under investigation for its feasibility in purifying wastewater from cassava-starch extraction. The pilot reactor, situated in a starch factory in the Cauca Department, will undergo evaluation from both technical and economic perspectives, with the collaboration of the Corporación Autónoma Regional del Valle del Cauca (CVC).
Wastewater from cassava-starch extraction, characterized by significant volumes and varying composition, presents a unique challenge. The traditional disposal method into rivers raises environmental concerns and diminishes water quality for other purposes. The transfilter technology offers a promising avenue for treating this type of discharge, addressing the high COD-to-BOD ratio and the specific challenges associated with cassava-starch production.
Waste-to-Value: Utilizing Solid Residues
One notable aspect of cassava-starch production is the generation of solid residues during the separation of water from starch in sedimentation tanks. This greyish material, known as mancha, primarily consists of a proteinaceous fraction. Instead of being considered waste, this material finds value as animal feed, showcasing the potential for a circular economy within the cassava processing industry. The innovative approach not only addresses environmental concerns but also emphasizes the importance of extracting value from byproducts, contributing to the overall sustainability of the industry.
Research and Development for Sustainable Solutions
The collaboration between UV, ORSTOM, and CVC extends beyond the application of transfilter technology. Laboratory research delves into the filtration capacity of different support materials, with a focus on paja de monte. The ongoing studies aim to determine the optimal compression of the support for efficient filtration, considering factors such as water velocity and density of the medium. These findings will inform the design of the pilot reactor, ensuring its effectiveness in real-world applications.
Additionally, the research encompasses the anaerobic digestion of filter effluent, exploring the potential for methanization and energy recovery. The adaptation of microbial biomass to low cyanide concentrations in wastewater highlights the resilience of the proposed technology. The comprehensive approach includes the study of bacterial microflora composition, distribution, and their roles in the biodegradation process. This knowledge contributes to refining the design and operation of the proposed wastewater treatment system.
Conclusion: A Sustainable Future for Cassava Processing
The case study of cassava-starch production in Colombia exemplifies the intersection of traditional practices, environmental challenges, and innovative solutions. The collaborative efforts between academic institutions, research organizations, and environmental agencies underscore the importance of addressing sustainability concerns in agroindustrial processes. As the pilot project progresses and the transfilter technology proves its efficacy in the starch factory in the Cauca Department, the potential for scalability and replicability across similar industries becomes evident.
The journey towards unlocking sustainable solutions for cassava-starch production waste management involves not only technological innovation but also a paradigm shift in viewing waste as a valuable resource. The circular economy principles embedded in the transfilter approach set the stage for a future where agroindustrial processes contribute to environmental preservation and economic growth simultaneously. As Colombia navigates its agricultural landscape, the integration of such sustainable practices becomes imperative for building a resilient and ecologically conscious future.