Current Trends and Future Developments on (Bio-) Membranes

Reverse and Forward Osmosis: Principles, Applications, Advances

Angelo Basile, Alfredo Cassano, Navin Kumar Rastogi, Navin K Rastogi

• Publisher: Elsevier
• Year: 2019
• Print ISBN: 9780128167779
• eBook ISBN: 9780128172995
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

Current Trends and Future Developments on (Bio-) Membranes: Reverse and Forward Osmosis: Principles, Applications, Advances covers the important aspects of RO, FO and their combination in integrated systems, along with their specific and well-established applications. The book offers an overview of recent developments in the field of forward and reverse osmosis and their applications in water desalination, wastewater treatment, power generation and food processing. General principles, membrane module developments, membrane fouling, modeling, simulation and optimization of both technologies are also covered. The book's ultimate goal is to support the scientific community, professionals and enterprises that aspire to develop new applications.- Provides an overview of the advances made in combining reverse osmosis membrane technology and the corresponding forward osmosis- Provides a comprehensive review of advanced research on membrane processes for water desalination, wastewater treatments, etc.- Addresses key issues in process intensification and extraction of energy from renewable sources- Identifies further research needs for the practical implementation of these two membrane technologies

Part 1

Forward osmosis

1

Forward osmosis: Principles, applications, and recent developments

Navin K. Rastogi Department of Food Engineering, Central Food Technological Research Institute, Council of Scientific and Industrial Research, Mysore, India

Abstract

Consumer demand for the highest quality concentrated products with natural flavor and taste, free from chemical additives and preservatives, has triggered the development of novel membrane-based processes for the concentration of liquid foods. Forward osmosis is one such alternative. The increase in scientific reports in the literature demonstrates the various emerging applications of this technology in food processing, desalination, and pharmaceuticals. The most vital capability of forward osmosis is concentration of liquid foods at ambient temperature and pressure without major fouling of the membrane. Low energy consumption, low fouling propensity, reduced or easy cleaning, low cost, high salt rejection, and high water flux are some of the advantages of forward osmosis over other membrane processes. The current limitations of forward osmosis are concentration polarization, fouling of the membrane, back diffusion of draw solute, and the design/fabrication complexities of suitable membranes. This chapter discusses the current advances in forward osmosis and focuses on the opportunities and challenges associated with this technology.

Keywords

Forward/direct osmosis; Fruit juice; Membrane; Hydrophilic; Osmosis; Desalination

List of acronyms

DS draw solution

ECP external concentration polarization

FO forward osmosis

ICP internal concentration polarization

NF nanofiltration

RO reverse osmosis

UF ultrafiltration

List of symbols

A and B active layer permeability coefficients of the membrane for water and solute, respectively

J_w flux

k mass transfer coefficient

Κ solute resistivity for diffusion within the porous support layer

Greek symbols

ΔP difference in pressure

π bulk osmotic pressure

π⁎ osmotic pressure on membrane surface

π′ osmotic pressure inside the active layer

Subscripts

d draw solution

f feed solution

w water

Acknowledgments

Thanks are due to the Director of CSIR-CFTRI, Mysore for his encouragement. The generous support of Dr. Edward G. Beaudry, Director of Process Development, Hydration Technology Innovations, United States, for providing membranes to continue the work in the area of FO, is gratefully acknowledged.

1 Introduction

Osmosis has been a subject of study in various scientific and engineering disciplines. It is well-defined as a method for transport of water based on the difference in osmotic pressure across a semipermeable membrane. Forward osmosis (FO) is defined as a membrane process in which the difference in osmotic pressure produces movement of water from the feed (dilute) solution (low osmotic pressure) side to the draw (concentrated) solution (high osmotic pressure) side, through a selectively permeable membrane. FO allows higher concentrations of juices without significant fouling of the membrane (Beaudry & Lampi, 1990a; Nayak & Rastogi, 2010a; Rastogi, 2016).

Also known by other names such as direct osmosis, engineered osmosis, and manipulated osmosis, FO concentrates liquid foods at ambient temperature. The process utilizes an osmotic solution to isolate water from a feed through a semipermeable membrane. In contrast, the reverse osmosis process requires hydraulic pressure as the driving force for separation.

Due to its low hydraulic pressure requirement, FO has several potential advantages in comparison to processes such as reverse osmosis (RO), nanofiltration (NF), and ultrafiltration (UF). Its main advantages over the conventional processing methods can be summarized as (Babu, Rastogi, & Raghavarao, 2006; Cath, Adams, & Childress, 2005; Cath, Gormly, et al., 2005):

• • Retention of fresh fruit flavor and nutritional/bioactive components
• • Minimum color degradation and improved product quality
• • Concentration at ambient pressure and temperature
• • Absence of thermal effects, so cooked taste is not imparted to the food
• • Reduction in membrane fouling propensity over pressure-driven membrane processes
• • Use of simple equipment and energy efficiency

Many fruit juices contain bioactive compounds such as vitamins, phenolic compounds, anthocyanins, and carotenoids. Once the colorants are extracted from plant s...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Preface
• Part 1: Forward osmosis
• Part 2: Reverse osmosis
• Part 3: Integrated RO/FO
• Index