Over the last few years, membranes have become the preferred treatment technology in municipal water and wastewater treatment. However, industrial treatment processes have continued to rely on conventional techniques. With recent improvements in membrane technologies, and with more stringent discharge requirements for industrial systems, membranes are becoming the preferred treatment technology for industrial processes as well.
Common applications for using membranes in industrial treatment systems include:
Secondary treatment, using Membrane Bio-Reactors (MBR), where BOD and TSS limits are being reduced.
Tertiary treatment, using low pressure membranes (e.g. Microfiltration), where the effluent is being reused.
Tertiary treatment, using high pressure membranes (e.g. Nanofiltration, Reverse Osmosis [RO]), when Total Dissolved Solids, metals, and emerging contaminants must be removed to meet tighter discharge requirements.
Most industrial wastewater streams contain higher organic loads, measured in thousands of mg/l BOD and COD, than municipal streams. Also, many industrial streams have high concentrations of TDS. Finally, peaking factors for industrial streams tend to be much higher than for municipal streams. These factors make industrial treatment systems challenging todesign.
This presentation provides information on how membranes have been or will be used in several industrial applications to achieve treatment targets throughout California.
Over the past decade membrane technologies have revolutionized water and wastewater treatment. In water, wastewater, recycled water, and industrial treatment applications, microfiltration (MF) and ultrafiltration (UF) membranes are typically used to separate solids from a fluid by physical straining. MF and UF systems provide a consistently high quality, low turbidity filtered water (typically less than 0.1 NTU) independent of the source water turbidity or solids variations. MF and UF treatment permits wastewater treatment plants (WWTP) to more easily meet more stringent effluent water quality requirements for discharge or recycling.
In wastewater and recycled water treatment applications, Nanofiltration (NF) and Reverse Osmosis (RO) membranes are typically used after filtration treatment to remove dissolved species such as salts and emerging contaminants. NF and RO treatment permits WWTPs to produce recycled water more suitable for irrigation and/or for recharge or for possible indirect potable reuse.
For years, the focus of membrane technologies was on large water treatment systems, especially publicly owned water systems. However, membranes for industrial wastewater treatment did not find their place until the early 1990s. By 2010 the use of membranes in industrial wastewater treatment is expected to increase 15% annually. In California, much of this growth has been due to increasingly stringent discharge regulations, especially relating to salts in effluent applied to land.
Membrane treatment of industrial wastewater and recycled water offers the advantages of higher effluent water quality, a more compact foot-print, and often times simpler operations as compared to a conventional WWTP. With the industry’s acceptance of this technology and the rapid growth in the number of operating facilities, the costs of membrane systems are now approaching conventional systems. Sooner or later, membranes will likely be in your future.
This paper presents a general overview of membrane technology, describes the specific applications of membranes in industrial wastewater and recycled water, provides a comparison of membrane vs. conventional industrial wastewater treatment, and describes several examples of how membranes were considered and/or used for industrial treatment.