Forward osmosis treatment of effluents from dairy and automobile industry - results from short-term experiments to show general applicability

Membrane applications in the food industry

Current trends in the food industry for the application of membrane techniques are presented. Industrial solutions as well as laboratory research, which can contribute to the improvement of membrane efficiency and performance in this field, are widely discussed. Special attention is given to the main food industries related to dairy, sugar and biotechnology. In addition, the potential of membrane techniques to assist in the treatment of waste sources arising from food production is highlighted.

Indirect effects of Covid-19 on water quality

The provision of safe water and functioning waste management play key roles in preventing and combatting disease outbreaks such as the Covid-19 pandemic. Good water quality is needed for effective hygiene measures like washing hands as well as for lowering pathogen transmission. Almost all over the world, especially in developing countries, water is vulnerable and at high risk and surging insecurity with time. Effective water management, sanitation, and hygiene help to protect lives during the global COVID-19 pandemic. While sanitation and hygiene also disturb the quality and increase water consumption per capita to 40% comparatively and wastewater production in many developing countries. This rapid increase in water consumption puts direct pressure on water reservoirs and inadequate management of wastewater is also a serious threat to waterways, nowadays. Similarly, the quality of water bodies is significantly affected by the COVID-19 pandemic, but the risk of transmission of COVID-19 through sewerage systems is recorded as low. Hence, the current review paper aims to highlight the main concerns directly linked with the frequent usage of detergents/soaps and alcohol-based hand sanitizers on water quality and the post-pandemic handwashing habits to overcome the COVID-19 spread also threatening the water reserve reservoirs via water high consumption along with more wastewater production with less water reuse efficiency and collectively the pressure on drinking water facilities. This review also focuses on the indirect influence of COVID-19 on water quality through technical interventions among COVID-19, water pollution; soaps/detergents, and hand sanitizer and the complete water management plan for water security and safety from policymakers to end users after the viral revolution briefly.

Sustainable Treatment of Food Industry Wastewater Using Membrane Technology: A Short Review

Water is needed for food processing facilities to carry out a number of tasks, including moving goods, washing, processing, and cleaning operations. This causes them to produce wastewater effluent, and they are typically undesirable since it contains a high volume of suspended solids, bacteria, dyestuffs, salts, oils, fats, chemical oxygen demand and biological oxygen demand. Therefore, treatment of food industry wastewater effluent is critical in improving process conditions, socio-economic benefits and our environmental. This short review summarizes the role of available membrane technologies that have been employed for food wastewater treatment and analyse their performance. Particularly, electrospun nanofiber membrane technology is revealed as an emerging membrane science and technology area producing materials of increasing performance and effectiveness in treating wastewater. This review reveals the challenges and perspectives that will assist in treating the food industry wastewater by developing novel membrane technologies.

A novel concept of Vertical Up-Flow Forward Osmosis reactor: Design, performance and evaluation

Performance of the forward osmosis (FO) process is limited due to the decline in water flux and increase in reverse salt flux. In this study, a novel Vertical Up-Flow Forward Osmosis (VUF-FO) reactor was designed and evaluated for eight different contacting patterns of feed and draw agent (DA). The best contacting pattern was compared with the basic H-shape reactor. Pulsating inlets were used for the recirculation of the feed and DA which helped in improving the performance by reducing the concentration polarization on membrane. Water flux in FO (active layer facing feed side) and PRO (active layer facing draw side) mode was 12.75 and 16.28 L/m²hr (LMH) respectively for the contacting pattern R3 and R5 after 8 h of the process. While the water flux in the H-shape reactor was 9.12 and 12.54 LMH for FO and PRO mode respectively. Diffusional behavior of water flux and reverse salt flux were also evaluated for both the FO reactors. Water flux in the H-shape reactor was declined to more than 60% from its initial value in both the modes (i.e. FO and PRO) due to the concentration polarization on membrane. Only 10% decline in water flux was observed for the VUF-FO reactor. This showed a better consistency of water flux in the VUF-FO reactor. The reverse salt flux in the VUF-FO reactor was less than 85% compared to the H-shape reactor. Therefore, a novel designed reactor improved the overall performance of FO in terms of water flux and reverse salt flux.

Volume reduction and water reclamation of reverse osmosis concentrate from coal chemical industry by forward osmosis with an osmotic backwash strategy

Coal chemical industry (CCI) generally utilizes reverse osmosis (RO) for water reclamation, which generates a highly concentrated stream containing refractory organic substances and high-concentration total dissolved solids (TDS). To address this issue, the present work focuses on volume reduction of RO concentrate (ROC) produced from CCI by forward osmosis (FO). We investigated the effects of membrane orientation and draw solution (DS) concentration on FO performance. Foulant removal was tested by using chemical cleaning, physical cleaning and osmotic backwash (OB). AL-FS (active layer facing feed solution) mode outcompeted AL-DS (active layer facing draw solution) mode, achieving a flux of 26.4 LMH, 92.5% water reclamation and energy consumption of 0.050 kWh·m^-3 with 4 M NaCl as DS. The FO process was able to reject >98% SO₄ ^2-, Mg²⁺and Ca²⁺, 92-98% Si and 33-55% total organic carbon (TOC). Ten-cycle (10 × 20 h) accelerated fouling test demonstrated approximately 30% flux decline in association with Si-containing foulants, which could be removed almost completely through OB with 97.1% flux recovery. This study provides a proof-of-concept demonstration of FO for volume reduction and water reclamation of ROC produced from CCI, making the treatment of ROC more efficient and more energy effective.

Membrane Technologies in Wastewater Treatment: A Review

In the face of water shortages, the world seeks to explore all available options in reducing the over exploitation of limited freshwater resources. One of the surest available water resources is wastewater. As the population grows, industrial, agricultural, and domestic activities increase accordingly in order to cater for the voluminous needs of man. These activities produce large volumes of wastewater from which water can be reclaimed to serve many purposes. Over the years, conventional wastewater treatment processes have succeeded to some extent in treating effluents for discharge purposes. However, improvements in wastewater treatment processes are necessary in order to make treated wastewater re-usable for industrial, agricultural, and domestic purposes. Membrane technology has emerged as a favorite choice for reclaiming water from different wastewater streams for re-use. This review looks at the trending membrane technologies in wastewater treatment, their advantages and disadvantages. It also discusses membrane fouling, membrane cleaning, and membrane modules. Finally, recommendations for future research pertaining to the application of membrane technology in wastewater treatment are made.

Modelling Forward Osmosis Treatment of Automobile Wastewaters

Forward osmosis (FO) has rarely been investigated as a treatment technology for industrial wastewaters. Within this study, common FO model equations were applied to simulate forward osmosis treatment of industrial wastewaters from the automobile industry. Three different models from literature were used and compared. Permeate and reverse solute flux modelling was implemented using MS Excel with a Generalized Reduced Gradient (GRG) Nonlinear Solver. For the industrial effluents, the unknown diffusion coefficients were calibrated and the influences of the membrane parameters were investigated. Experimental data was used to evaluate the models. It could be proven that common model equations can describe FO treatment of industrial effluents from the automobile industry. Even with few known solution properties, it was possible to determine permeate fluxes and draw conclusions about mass transport. However, the membrane parameters, which are apparently not solution independent and seem to differ for each industrial effluent, are critical values. Fouling was not included in the model equations although it is a crucial point in FO treatment of industrial wastewaters. But precisely for this reason, modelling is a good complement to laboratory experiments since the difference between the results allows conclusions to be drawn about fouling.

Forward Osmosis Application in Manufacturing Industries: A Short Review

Forward osmosis (FO) is a membrane technology that uses the osmotic pressure difference to treat two fluids at a time giving the opportunity for an energy-efficient water and wastewater treatment. Various applications are possible; one of them is the application in industrial water management. In this review paper, the basic principle of FO is explained and the state-of-the-art regarding FO application in manufacturing industries is described. Examples of FO application were found for food and beverage industry, chemical industry, pharmaceutical industry, coal processing, micro algae cultivation, textile industry, pulp and paper industry, electronic industry, and car manufacturing. FO publications were also found about heavy metal elimination and cooling water treatment. However, so far FO was applied in lab-scale experiments only. The up-scaling on pilot- or full-scale will be the essential next step. Long-term fouling behavior, membrane cleaning methods, and operation procedures are essential points that need to be further investigated. Moreover, energetic and economic evaluations need to be performed before full-scale FO can be implemented in industries.