sign in sign up
<<
Home , Purified water, Water purification

Hitachi Review Vol. 62 (2013), No. 4 272 Industrial Waste Treatment System for Water

Toshimasa Akamatsu OVERVIEW: Many countries and regions around the world are facing threats Noboru Oda of severe water shortages or degradation of the water environment resulting from factors such as explosive population growth, rising living standards brought about by economic progress, and increasing use of industrial water. Using the advanced technologies of systems, information and control systems, and energy saving systems, Hitachi has been helping protect and improve the world’s water environment for about a century. In the future, Hitachi intends to continue utilizing its high levels of both hardware and software technology built up in a variety of water-related fields to work with customers on building water distribution systems.

INTRODUCTION differ between the numerous industrial sites located WITH a small land area and limited resources, Japan around the region. has achieved economic growth through the strength One example is how some industrial sites with of its manufacturing and other industrial operations. centrally managed waste water treatment facilities However, this resulted in and other are permitted to operate to looser standards than the environmental problems, and restrictions stipulated host nation’s quantitative rules. This makes it essential by a number of different laws have been placed on to conduct preliminary studies when considering the the discharge of water by companies involved in construction of a plant. industrial activity. Other countries have had similar Considering the quality of industrial water supplies, experiences, with Southeast Asia and other emerging there are also examples of companies installing economies, in particular, facing severe water shortages their own systems for improving to and degradation of their water environments resulting suit the intended end use. In India, meanwhile, top from factors such as increasing use of industrial water priority is given to irrigation to conserve precious and rising living standards brought about by economic water resources. Measures include the placement of progress. restrictions on use of water for production at industrial It is against this environmental and social and other sites, and also encouragement for water background that Hitachi supplies total solutions recycling (“zero discharge” practices). for protecting the water environment and making These factors mean that companies operating in improvements. Southeast Asia and other emerging economies need to This article reviews the water situation in Southeast build their own water treatment systems in accordance Asia and other emerging economies, and describes with local circumstances. the industrial water treatment systems that Hitachi is offering in response.

CHANGING WATER ENVIRONMENTS IN ASIA The water-related environmental laws in Japan include the Control Law enacted under The Basic Environment Law. These laws provide the basis for detailed regulatory limits for specific industries or locations, including those (a) (b) specified in the bylaws issued by local governments. Fig. 1—-type Treatment System (a) A similar legal framework applies in Southeast and Exchange Tower. Asia, with each nation stipulating quantitative rules for These photographs show a compact module for a membrane- various water discharge criteria. A distinctive feature type drinking water treatment system (a), and the is that these quantitative rules on water discharges tower for use in production of soft (b). Industrial Waste Water Treatment System for Water Recycling 273

HITACHI WATER TREATMENT SYSTEMS that has emerged in recent years is the membrane In Japan and elsewhere, Hitachi has built up bioreactor system. Combining activated extensive experience and know-how in both hardware treatment with an immersed flat membrane to perform and software for a diverse range of water-related fields. highly concentrated activated sludge treatment, this This section describes the industrial water treatment system is suitable for industrial waste water treatment systems that are included among these technologies. where the requirements are for a high level of treated water quality together with ease of maintenance, space Water Treatment Equipment efficiency, and low cost (see Fig. 2). Membrane-type drinking water treatment systems Another consideration is that many countries have that use membrane filters to purify water to a level established regulations on the presence of nitrogen acceptable for drinking represent one form of water in waste water. This is in response to the severe treatment. Compact and easy to maintain, these impacts that the discharge of nitrogen in waste water systems provide a choice of (MF), into oceans or can have on ecosystems, such as (UF), and other types of , as various types of algal blooms. appropriate, based on the water quantity and quality The method used to deal with nitrogen in waste requirements, and can remove as well water involves first using a treatment as (E. coli) and other . in which a long-duration aerobic treatment process Some industrial applications require high-quality using activated sludge converts ammonium nitrogen purified water. In this case, water purification units into nitrogen. This is followed by the use of fitted with components such as ion exchange towers or denitrifying under anaerobic conditions to reverse (RO) membranes are used to remove covert the nitrate nitrogen into nitrogen gas. impurities such as , colloidal matter, and To perform this waste water treatment efficiently, low- or high-molecular-weight organic material (see Hitachi has developed a comprehensive immobilizing Fig. 1). nitrogen removal system. This system enhances the capacity of the nitrification treatment process by using Waste Water Treatment Equipment nitrifying pellets (inclusive immobilization supports) The waste water produced by industrial activity in which the microorganisms that form the activated can be broadly divided into organic and inorganic sludge are encapsulated into 3-mm square cubes of waste water. agar-like aqueous gel (see Fig. 3). Treatment of organic waste water typically involves In addition to boosting the efficiency of nitrogen biological methods based on the use of activated removal, this system uses only about half as much sludge. Another type of biological treatment system

Raw Pollutants water Nitrifying pellets Separator P Chemical Screen Flocculant cleaning Cleaning pump chemicals tank Blower P Treated Treated B water water Membrane filter pump

Agitator Membrane module Biological reaction tank Polymer aqueous gel

Anaerobic tank Aerobic tank Excess P sludge P Sludge 3 mm removal Microorganisms Circulation pump (nitrifying bacteria) pump B: blower P: pump Nitrifying pellets Fig. 2—Membrane Bioreactor System. Fig. 3—Comprehensive Immobilizing Nitrogen Removal System. The figure shows a simplified flow diagram of a membrane The figures show the principle of operation of the bioreactor system that combines activated sludge treatment and comprehensive immobilizing nitrogen removal system and the an immersed flat membrane. immobilization supports used. Hitachi Review Vol. 62 (2013), No. 4 274

Circulated fluid B Nitrifying pellets

Primary Treated Fig. 4—System Flow Diagram treated water water of Comprehensive Immobilizing Nitrogen Removal System. Final P This shows the standard Denitrification tank Nitrification tank sedimentation Submergible tank configuration of a aerator comprehensive immobilizing Returned sludge nitrogen removal system. space as previous methods. Hitachi has had extensive One distinctive technology of Hitachi is its experience with this technology over many years (see advanced fluorine treatment device (see Fig. 5). This Fig. 4). Hitachi is now developing a system for treating device converts the residual fluorine in water treated waste water with a high nitrogen concentration that using that contains hydrofluoric to uses inclusive immobilization supports embedded apatite, and then precipitates it on the surface of a with anaerobic ammonium oxidation (ANAMMOX) crystallized material. It uses an expanded-layer reactor bacteria capable of removing nitrogen directly structure that makes it simpler, easier to maintain, from ammonium nitrogen. Because this inclusive and less costly than existing two-stage coagulation immobilization technology also has the potential for sedimentation devices (see Fig. 6). deployment in other applications, Hitachi is proceeding with further research and development, including its Equipment for Water Reuse use for the removal of other restricted substances. Hitachi has for some time been developing In the case of inorganic waste water, on the other systems that combine RO membranes with membrane hand, it is necessary to choose a treatment method that bioreactor systems, and that are targeted particularly at suits the substance to be removed. regions that suffer from water shortages. These systems

Circulated water

Treated water

Crystallized Phosphorous-based material reagent

Discharge (water flocculated Excess crystallized using hydrated ) material (drained periodically)

Fluorapatite precipitates on the surface of Phosphorus the crystallized material Fluorine

Crystallized material

5Ca+3PO4+F Ca5(PO4)3F (Fluorapatite)

Fig. 5—Principle of Operation of Advanced Fluorine Treatment Device. Fig. 6—Advanced Fluorine Treatment Device. The diagram shows the principle of operation of this advanced This advanced fluorine treatment device is based on a fluorine treatment technology based on a precipitation reaction. precipitation reaction. Industrial Waste Water Treatment System for Water Recycling 275

UF membrane RO membrane

Waste water

Raw water P Waste water treatment Intermediate Sand Filtered water Activated pump equipment tank filter tank

Plant Treated water pump RO membrane RO Water for reuse inlet water Fig. 7—Example of Equipment P P tank for Water Reuse Supplied by Treated water RO pump Hitachi. Example flow diagram of tank system for water reuse Hitachi supplied this waste water recycling plant that uses UF: ultrafiltration RO: RO membranes. recycle water and supply it as high-purity treated water construction and make changes as required. Hitachi (see Fig. 7). Hitachi is also investigating systems that has technology and experience in a wide range of recover and reuse rainwater so that it can be provided industrial water treatment systems able to comply with as a resource for regions with limited water sources. these regulations, as discussed along with examples in While rainwater is often stored for use in emergencies this article. These include water treatment using MF, after its contaminants have been removed, it can also UF, RO, and other types of membranes, organic waste be treated to make it suitable for various uses. water treatment using nitrifying pellets (inclusive Water recycling systems can be built by using immobilization supports), advanced fluorine treatment the fresh water and waste water treatment systems based on a precipitation reaction, and systems for described above to treat resources such as waste water water reuse that combine RO membrane equipment and rainwater that have not been reused in the past. with a membrane bioreactor system. As a wide range of potential applications exist for water reuse, extending from general water supplies and the makeup water used in cooling towers to the ABOUT THE AUTHORS highly treated water required by factories, Hitachi is seeking to work with customers to build systems that Toshimasa Akamatsu ensure the efficient use of water at production sites Joined Hitachi Plant Engineering & Construction Co., and other facilities. Ltd. in 1992, and now works at the Project Incubation Department, Water Environment Solutions Business Management Division, Infrastructure Systems CONCLUSIONS Company, Hitachi, Ltd. He is currently engaged in the This article has reviewed the water situation in planning of industrial water treatment systems. Southeast Asia and other emerging economies, and described the industrial water treatment systems that Hitachi is offering in response. Noboru Oda Joined Hitachi Plant Engineering & Construction Co., While emerging economies set waste water Ltd. in 1974, and now works at the Water Treatment standards equivalent to those in Japan, the regulations Division, Infrastructure Systems Company, Hitachi, differ from nation to nation. This makes it necessary Ltd. He is currently engaged in the planning of to investigate this issue before embarking on plant industrial water treatment systems.