Rochem provides equipment and services for the recovery of high quality water and the removal of toxic contaminants from industrial wastewater and process wastewater streams.
Process Separation Technologies for Petroleum Wastewater Streams and Petrochemical Wastewater Streams
Our vision is to be a primary source of key process separation technologies and services for ships at sea, refiners, chemical manufacturers and other companies with difficult to handle petroleum wastewater streams and petrochemical wastewater streams. Rochem endeavors to combine innovative process engineering strategies with synergistic technologies to provide customers the most beneficial, cost effective system options for meeting their needs. Rochem is synonymous with:
- quality equipment and services that enable industry to meet tomorrow`s most difficult environmental challenges,
- proprietary equipment design that is a breakthrough in reliability,
- proven ultrafiltration equipment for wastewater treatment and process separations,
- cost effective technology for environmental management
- up to 99+ percent removal of target contaminants at a lower cost than any other comparable system
Disc Tube (DT) Membrane Module, Industrial Leachate Treatment (Liquid Toxic Waste), Feed Water Cross Flow System, Reverse Osmosis (RO)
The ROCHEM group of companies was founded in 1973 with a vision to serve the needs of marine customers in the marine chemical and maintenance field in all major ports worldwide. Today, marine installations exist in over 50 countries and ROCHEM has expanded to include numerous non marine industrial projects. ROCHEM first introduced reverse osmosis (RO) into its product line in 1982 when in began marketing its G4 module. The introduction followed licensing of the G4`s plate technology by GKSS. At the time, ship owners were having operational difficulties with competitive reverse osmosis (RO) technologies. This led ROCHEM RO WASSERBEHANDLUNG GMBH to embark upon a research and development program to produce a membrane module. In 1986, the project resulted in the Disc Tube (DT) membrane module technology that received worldwide patent coverage. ROCHEM`S DT Module uses a unique membrane module construction that results in an open channel, unrestricted and fully turbulent feed water cross flow system configuration. The turbulence prevents suspended solids carried in the feed water from being trapped or settling inside the membrane module. As a result, infrequent and highly successful maintenance cleaning of the membrane is achieved using a standard inbuilt cleaning system. Unlike other reverse osmosis (RO) systems, the need for pretreatment of seawater feed with acid or other chemicals is eliminated. The system guarantees full performance, high reliability and greatly extended membrane life.
The ROCHEM reverse osmosis (RO) plants are shipboard system favorites. Over 1200 installations with varying capacities ranging from small vessels to the very largest, including the NATO navies, are in daily use all over the world. Their modular construction allows the flexibility to make system design and installation relatively easy on any vessel. Certified by all well-known classification societies, the systems provide fully automatic operation and are easy to maintain. ROCHEM is unique because of its multi faceted approach to effective filtration. The ROCHEM GROUP combines the following to produce outstanding systems:
- research and development
- technical know how
- patented products
- module manufacturing
- system design and engineering
- system installation
- direct contact with the end user
The expertise gained from its experience in the marine industry has enabled ROCHEM to design and build reverse osmosis (RO) systems for other applications such as industrial plants and hotels. In 1989, ROCHEM entered the industrial leachate treatment (liquid toxic waste) market for landfill locations, one of which was Schonberg, the largest waste disposal site in Europe. Due to its DT module technology and advanced plant technology, ROCHEM quickly became a leader in the market reaching over $40 million in sales with 150 employees in 21 countries.
UF Membrane System, BIOFILT, Aerobic Biological Sewage Plants, Grey Water Treatment, FM Module
At the beginning of 1998, PALL Corp., U. S. A, one of the largest suppliers of filtration equipment in the world, acquired the right to market certain ROCHEM products including its DT technology. PALL established PALL ROCHEM WASSERTECHNIK, headquartered in Hamburg, to promote and sell reverse osmosis (RO) systems worldwide. Meanwhile, the ROCHEM Group was using the knowledge and experience gained through its leachate installations to develop new reverse osmosis (RO), nanofiltration and ultrafiltration technologies. Existing ultrafiltration systems on the market were beset with problems in attempting wastewater treatment of water containing fouling impurities and suspended solids. It developed its new patented membrane module to add to its line of products. Known as the FM module, this new technology can address special requirements such as grey water treatment on ships to meet environmental discharge requirements. The FM module is also used to treat and convert surface water to drinking water on shore. The ROCHEM Group established the ROCHEM UF SYSTEME GmbH, located in Hamburg in 1998, to promote and sell BIOFILT, a newly designed bioreactor. Its special treatment technology is intended to replace conventional aerobic biological sewage plants aboard ships. Based on a high density biological process combined with a UF membrane system, BIOFILT will produce a pure, clean discharge without requiring additional chlorination or other chemical treatment. By treating all wastewater and sewage water on sea going ships with BIOFILT before discharge overboard, marine life and organisms will be protected and a truly ``environmentally sound ship`` is achievable. ROCHEM products are available through a number of subsidiary companies and agents worldwide.
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Rochem FM modules (Flat Membrane) have been developed for the separation of germs and solids from wastewater with a high fouling potential using ultrafiltration membranes. Other applications are for solving separation problems in water treatment and purification using nanofiltration or low pressure reverse osmosis membranes.
Rochem FM- Module System
The FM module is characterized by low energy demand as well as high and constant flux rates. Unique to the FM module is the flexible adaptation of the module to specific technological demands by the variation of membrane material, the dimension of the feed water channel and the operating mode. The patented FM module is a membrane cushion module with a completely open feed water channel (no distance spacer between the membrane cushions) and a feed flow without flow deflections (axial symmetrical straight through feed flow). This combines the advantages of open channel construction that ensures efficient cleaning, usual tubular channel modules and flat channel modules with the advantages of the narrow gap technique that minimizes dead volume and low energy demand. Due to the capability of varying the space between the membrane cushions, the FM module can be used for a wide range of suspended solid concentrations in the feed water. The vertical installation of the module allows for a very efficient rinsing and cleaning of the membranes with an air/ water mixture. This ensures long operating periods without the demand for chemical cleaning.
Low Pressure, Reverse Osmosis and Nanofiltration
The driving force for the separation of dissolved components from water in low pressure reverse osmosis and nanofiltration is a pressure differential across the membrane. In both processes the water to be treated is separated by means of a solution diffusion membrane (``tight`` membrane) into a partial stream of purified permeate and a remaining concentrate water stream. In the purified permeate, which is the liquid that has permeated through the membrane, the concentration of the components dissolved in the water is reduced in accordance with the rejection rate specific to the membrane. An economical operation can be achieved if the plant design and the operating mode limiting factors for processes such as scaling, fouling and/ or biofouling have been considered. The unique design and hydraulic properties of the Rochem FM module are the basis for a highly functional, safe and stable long term operation.
Nanofiltration membranes contain ionogenic groups. This causes an ion selectivity and thus the special separation properties of this process: the separation of dissolved multivalent components in aqueous media. The rejection rate for salts with monovalent ions is low whereas salts with bivalent ions and organic matter are retained to a high degree. Applications of nanofiltration in combination with the Rochem FM module are:
- reduction of hardness or sulfate in drinking water
- desalination of whey retaining lactose and proteins
- decolorization of wastewater in the textile and cellulose industry
Reverse osmosis (RO) membranes separate molecules with the molecular weight above 100g/ mol almost completely. This causes high rejection rates for organic and inorganic components dissolved in water such as salts. Low pressure reverse osmosis is operated in a pressure range up to 20 bar. Its applications include:
- reduction of salt content in drinking water
- reduction of contaminants in drinking water
- purification of waste water with low TDS burden
- concentration of process fluids
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Rochem FM modules with ultrafiltration membranes have been developed especially for the separation of bacteria, viruses and fine solids from water and wastewater with the high fouling potential.
FM Modules, Ultrafiltration, Low Specific Energy Consumption, Feed Path Space
Ultrafiltration is based on porous membranes. Particles larger than the pore size of membranes are rejected. In practice even smaller particles are rejected because of the selectivity of the filter cake (gel layer) on the membrane surface. Therefore ultrafiltration membranes form an absolute barrier for bacteria and viruses including colloids and macromolecules. Rochem FM modules exhibit very low specific energy consumption at high and steady state fluxes. It has the unique possibility of an optimal adaptation of the feed path space (distance between membrane cushions) for the individual case. This feature allows for applications in a wide range of solid concentration.
Rochem plant design
Rochem plants for low pressure reverse osmosis and nanofiltration equipped with the FM module system are delivered ready for operation as standardized units constructed in modular sections and factory tested.
The plants are manufactured as compact stainless steel profile frame construction with vertical or horizontal arrangement of the modules. This allows for the installation in a building, as well as in a container. The amount of permeate to be produced with a plant for each specific application is achieved b the installation of a corresponding number of modules giving the required membrane area. The basis for the design is the specific permeate production (flux) of the membrane given in liter per meter square an hour. This value is based on experience or has to be determined by pilot tests. The possibility to alter the volume stream by a partial stream recirculation on the feed side in plants from Rochem increases the technological flexibility and the process safety.
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