DataSheet1_A Bioelectrochemical System for Waste Degradation and Energy Recovery From Industrial Coffee Wastewater.PDF

The primary production of coffee involves the extensive use of water resources, since it is not only used for irrigation of coffee plantations, but it is also required in large volumes for the processing of the coffee berry to obtain high quality green beans. It is calculated that for every kg of dry coffee grain produced, up to 40 L of water are consumed, and its disposal represents a significant environmental problem, since most coffee growers are small producers with no access to efficient technologies for wastewater treatment. This situation leads to these liquid wastes to be discarded untreated in natural water sources, generating environmental pollution and public health problems. Bioelectrochemical Systems (BES) have been proposed as an alternative to conventional wastewater treatments, either as a primary bioremediation strategy or for secondary wastewater treatment systems. Among BES, microbial fuel cells (MFCs) are designed to exploit the metabolic capability of andophilic microorganisms to degrade the organic matter present in the waste. Anodophilic microorganisms use electrodes as terminal electron acceptors, generating a flow of electrons that can be used in the generation of electricity. In this work, we evaluated the ability of native microbial communities to degrade the organic matter present in wastewater from the coffee agroindustry and its electrogenic potential for the co-generation of electricity was evaluated using an MFC device developed by the authors. Wastewater samples obtained at different stages of the coffee wet process were used as inoculum and feedstocks. The system was operated in fed-batch, in both open and closed-circuit conditions, for 60 days. The degree of decontamination or bioremediation of the wastewater was assessed by measurements of physicochemical parameters. For the characterization of the native microbial community, microscopic and molecular techniques were used and the electrogenic potential was established by assessing the electrochemical performance of the system. With the proposed bioelectrochemical system, a reduction of up to 70% of the initial content of organic matter of the residual water from the coffee benefit was achieved, and open circuit voltages of up to 400 mV were recorded, comparable to those reported for conventional air breathing cathode MFC.

咖啡初级生产过程中水资源消耗量巨大，这是因为其不仅需用于咖啡种植园的灌溉，还需大量投入以加工咖啡浆果以获得高品质的生咖啡豆。据测算，每生产1千克干咖啡籽粒，需消耗多达40升水，而其废水处置已成为严峻的环境问题——多数咖啡种植者为小型生产商，无法获取高效的污水处理技术。此类液态废弃物常未经处理便被直接排入自然水体，进而引发环境污染与公共健康问题。

生物电化学系统（Bioelectrochemical Systems, BES）已被提出作为传统污水处理技术的替代方案，既可作为初级生物修复策略，也可应用于二级污水处理系统。在BES范畴内，微生物燃料电池（microbial fuel cells, MFCs）旨在利用阳极亲和微生物的代谢能力降解废弃物中的有机质。阳极亲和微生物以电极作为终端电子受体，产生可用于发电的电子流。

本研究评估了本土微生物群落降解咖啡农业产业废水中有机质的能力，并借助研究团队自研的MFC装置，评估了其实现电能联产的产电潜力。实验采用咖啡湿法加工不同阶段采集的废水样品作为接种物与进料基质。该系统以补料分批模式运行，分别在开路与闭路条件下持续运行60天。通过理化参数测定评估废水的净化程度与生物修复效果。为表征本土微生物群落，研究采用了显微技术与分子生物学手段，并通过评估系统的电化学性能确定其产电潜力。

借助所提出的生物电化学系统，本研究实现了咖啡加工残水中有机质初始含量最高70%的去除率，且测得的开路电压可达400mV，与传统空气阴极MFC的已有报道值相当。