Environmental and process assessment of a vibratory nanofiltration system for the recovery of water from soluble coffee manufacturing waste

Abstract

A case study has been conducted for the recovery of water from complex wastewater at a soluble coffee manufacturing factory. The study has evaluated separation methods for process intervention based on environmental and economic assessments. A novel vibratory field membrane separation was evaluated at the laboratory scale using actual factory wastewater, and was scaled‐up using appropriate design protocols. The recovery of water from an intermediate waste stream proved the most effective, both environmentally and economically. The proposed full‐scale vibratory membrane process recovers 378,541 L of water per day that meets specifications for reuse in the factory cooling tower. The proposed design reduced the daily well freshwater withdrawn by 21% and the amount of wastewater discharged from the factory by 28.5%. Annual operating costs were reduced by 22.5% and total life cycle emissions were reduced by 27.8%. These reductions are mainly the result of the reduced volume of wastewater discharged from the factory and the reduced energy requirement of the on‐site pretreatment processes. Economic assessment showed a net present value after 10 years is $181,100, while the payback time is under 3 years. Overall, the proposed vibratory membrane process used for water recovery presents favorable economics, and significant environmental emission reduction.

Mathematical modeling of vibratory shear‐enhanced nanofiltration in the preconcentration of coffee extracts for soluble coffee manufacturing

“…Also, the components of the coffee extract are potential membrane foulants that vary in particle size and charge and limit the performance of the operation. Thus, it is expected that higher feed coffee extract concentrations result in The enhanced flux was also observed in parallel vibratory membrane filtration studies for recovering yeast from suspensions by MF (Akoum et al, 2002), concentrating milk proteins by vibratory UF (Akoum et al, 2005), brackish water purification by vibratory RO (Shi & Benjamin, 2009), and in NF studies for soluble coffee extract and wastewater (Wisniewski et al, 2020;. The effectiveness of the novel dynamic vibratory filtration system is dictated by the membrane filtration principles affecting its performance, particularly from the local shear rates developed on the membrane surface during operation (Akoum et al, 2002;Frappart et al, 2006;Zsirai et al, 2016).…”

“…This study used a Series L-101 VSEP filtration system (New Logic Research, Inc.), as schematically presented in Figure 3. The same system has been investigated in past vibratory membrane filtration studies on microalgae (Slater, Savelski, Kostetskyy, & Johnson, 2015), soluble coffee wastewater reclamation (Wisniewski et al, 2020;, and in the scale-up design of coffee extract preconcentration by vibratory NF . A flow pump draws the feed sample from .…”

“…In contrast with thermal evaporation and drying, membrane separation prevents the damage or loss in food product quality (Brennan, 2012;Smith, 2011); and consumes less energy as these do not rely on phase-change water removal mechanisms (Madaeni & Zereshki, 2010). More importantly, commercial membranes developed to date have high rejection efficiencies, allowing the recovery of reusable water for ancillary plant operations to reduce freshwater consumption and wastewater generation Wisniewski, Laurio, Slater, & Savelski, 2020).…”

“…The process consumes up to 30 kg of water to produce 1 kg of soluble coffee product (Clarke & Macrae, 1987); while the conventional water removal operations consume up to 15.6 MJ of energy per kilogram of soluble coffee produced, the highest among powdered food processes (Wang, 2014). The water used for extraction also ends up as wastewater that requires treatment (Wisniewski et al, 2020;. Vincze and Vatai (2004) proposed the nanofiltration (NF) of coffee extracts as a preconcentration alternative to evaporation prior to final dehydration step, thereby addressing the water-and energy-intensive steps.…”

“…The vibrations impart high membrane surface shear rates (20,000-160,000 s À1 ) that overcome those generated from CF velocities (<30,000 s À1 ) and reduce membrane fouling (Akoum, Jaffrin, Ding, Paullier, & Vanhoutte, 2002;Bian, Yamamoto, & Watanabe, 2000;Ding et al, 2015) The system has been studied in the concentration of milk proteins and dairy wastewater treatment (Akoum, Jaffrin, & Ding, 2005;Kertész, Lászl o, Forgács, Szab o, & Hodúr, 2011), clarification, and yeast recovery of alcoholic beverages, (Akoum et al, 2002;Fillaudeau et al, 2007) and water treatment from high salt seawater and freshwater sources (Petala & Zouboulis, 2006;Shi & Benjamin, 2009;Su, Li, Palazzolo, & Ahmed, 2018;Subramani, DeCarolis, Pearce, & Jacangelo, 2012). Initial studies conducted by Laurio and Slater (2020) for coffee extract preconcentration, and by ; Wisniewski et al (2020) on soluble coffee wastewater reclamation, showed that vibratory shear enhancement improved permeate fluxes from NF operation by up to four times higher than those obtained from CF filtration, with minimal flux decline. When considered as a supplemental operation to thermal evaporation, preliminary evaluation of the scaled-up operation shows great potential to recover reusable water, reducing freshwater usage, wastewater generation, operating costs, and environmental emissions altogether.…”