Development. Mode of action. Cl 2 + EtHN

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1 A Subsidiary of Great Lakes Chemical Corporation Tenax Road Trafford Park Manchester M17 1WT United Kingdom Phone +(44) Fax +(44) Product Information Bellacide 325 algal control agent General Product Information Bellacide 325 is a fully stabilised 4%w/w aqueous dispersion of 2-chloro-4,6 dialkylamino-s triazine. It has a synergistic action in combination with chlorine, bromine and halogen release agents, and is used to control the wide range of algae found in cooling systems. Routine treatment with Bellacide 325, together with intermittent or continuous dosing of halogen, ensures prolonged protection against all identified strains of algae, even at low halogen concentrations. Summary The synergistic combination of Bellacide 325 and free halogen has the following in use properties and advantages over traditional algal control agents:! lower levels of both Bellacide 325 and oxidising biocides can be used for algal control. The cost of treatment is lower and lower discharge level of biocides from cooling water systems can be achieved, thus reducing their potential aquatic toxicity.! no build up of resistance due to the mode of action of the treatment. Bellacide 325 and halogens have a different mode of biocidal action which ensures micro-organisms cannot become resistant.! allows oxidising biocides to be more effective against bacteria and fungi because there is no halogen demand from algae. Development Ref: b325gpi.doc August 2 Bellacide 325 was specifically selected for use in cooling water applications. The development work involved two distinct phases: preliminary screening and dynamic experiments under simulated operating conditions. Mode of action Bellacide 325 selectively controls the growth of all algae by inhibiting photosynthesis. Bacteria and fungi are therefore unaffected because they do not rely on photosynthesis for growth. The triazines inhibit the photoreduction of water (Hill reaction) in photosynthesis. This is a process of light-induced electron transport, whereby light energy is trapped in a pigment system (chlorophyll) and converted to chemical energy. This energy is then used at a later stage for the fixation of carbon dioxide (Calvin cycle), which provides sugars and a carbon source for the growth of algae. Mechanism of synergy with halogens It is believed that the synergistic action of Bellacide 325 and halogen is achieved by the formation of a halogenated adduct on exposure of Bellacide 325 to free available halogen in cooling water. This occurs by reversible replacement of the ethyl amine hydrogen by either a chlorine or bromine atom. The algal control activity of this adduct is much higher than either the halogen or Bellacide 325 alone.! in cooling systems without process leaks, the main source of nutrient for bacteria is produced by algae. So once the algae are controlled it is easier to control other microorganisms.! Bellacide 325 does not foam, is compatible with scale and corrosion inhibitors, and is not lost by adsorption on to organic material. Cl 2 + EtHN Cl Cl N N N N N NHBu t EtCIN N NHBu t! regular use of Bellacide 325 eliminates many of the problems caused by unchecked algal growth i.e. loss of cooling efficiency, increased corrosion, blockages and unsightly visible contamination.! can be easily and directly applied to industrial water circuits. The information contained in this product sheet is based on data available to Bio-Lab Inc., and is thought to be correct. Since Bio-Lab, Inc,

2 Dosing recommendations for Bellacide 325 In a clean system In the presence of halogens, mg/l Bellacide 325 (product) should be maintained. The halogen can either be shock dosed (e.g. to give.5-1mg/l free halogen for 1 hour once per day) or continuously dosed (e.g. to give.1-.3 mg/l free halogen). In the absence of halogens, 75mg/l Bellacide 325 (product) should be maintained depending on the algal strains present. Note It is important that the residual Bellacide 325 level does not fall below 12.5 mg/l in the system water. System badly fouled with algae 5-75mg/l Bellacide 325 (as product) should be maintained in the presence of free halogen until algae are removed from the system. Alternatively, the system can be cleaned manually or chemically using a broad spectrum bleaching. The treatment used for clean systems can then be adopted when the algae have been removed. Methods of analysis Methods of analysis have been developed for Bellacide 325. They are not suitable for use in the field and require expertise in the areas of thin layer chromatography and high performance liquid chromatography. Please contact your BioLab Water Additives representative for further details. Typical properties The following are typical properties and should not be regarded as specification limits: physical form and pale-coloured dispersion appearance ph of undiluted product 7-9 active ingredients content g/l solubility in water of active ingredient in water miscible at low concentrations 8.5mg/l solids at 2 C viscosity 4-8 cp Packaging Bellacide 325 can be supplied in 25 kg (net) non-returnable containing either 25kg or 2kg or in 1kg non-returnable intermediate bulk containers. Patents BioLab, Inc. owns or is licensee of patents and patent applications which may cover the products and/or uses described in this brochure The following are trademarks of BioLab, Inc.:- Bellacide, Belcor, BioLab Logo, Waterfront Logo Registered US Patent and Trademark Office 2 BioLab, Inc. All rights reserved. Tenax Road, Trafford Park PO Box 1489 Manchester Decatur M17 1WT GA United Kingdom USA Telephone (44) Telephone (1) / Fax (44) Fax (1) Telex Visit our Website on The information contained in this product sheet is based on data available to Bio-Lab Inc., and is thought to be correct. Since Bio-Lab, Inc,

3 A Subsidiary of Great Lakes Chemical Corporation Tenax Road Trafford Park Manchester M17 1WT United Kingdom Phone +(44) Fax +(44) Product Information Bellacide 325 algal control agent Case studies: Application of Bellacide 325 in different cooling systems Ref: b325casestud.doc January 2 Abstract Bellacide 325 is a 4% aqueous dispersion of terbuthylazine (TBZ) and is widely used to control the growth of algae in recirculating cooling systems. Two case histories are discussed. The first describes how Bellacide 325 was used to clean up the cooling system of a metal sections plant in West Germany and to prevent regrowth of algae. In the second trial at a fertiliser plant, Bellacide 325 was used to control algae following unsuccessful trials with a variety of biocides. In both cases Bellacide 325 was used in conjunction with low level halogenation. Conclusion Both case histories demonstrate the excellent properties of terbuthylazine. Plant performance was greatly improved owing to the reduction of microbiological fouling. Furthermore, chlorine usage in the system was substantially reduced The System The manufacturer of metal sections in West Germany has a cooling system with the following parameters: Volume Recirculation rate Make-up Purge Typical cooling water temperature - inlet 68 F - outlet 69.8 F System half life 4 days Concentration factor m gallons.47 m gallons/hour.29 m gallons/hour.13 m gallons/hour This system operates under high heat load with water distributed from one hot water reservoir to five separate cooling towers, below which are situated five cold water reservoirs. All the reservoirs are exposed to light. The make-up and recirculating water analysis is as follows: Total hardness (as CaCO 3) Phenol alkalinity (as CaCO 3) Methyl alkalinity (as CaCO 3) Chloride as Cl - 2- Sulphate as SO 4 ph The Problem Make-up Circulating Water Before the introduction of Bellacide 325 the cooling water was treated with sodium hypochlorite (NaOCl) to control microbiological growth, but the algal growth was not controlled, even though the circulating water was regularly dosed with up to 1mg/l free chlorine. The circulating water was green due to suspended algal cells, and there were algal deposits on the walls of the reservoirs and cooling towers. Analysis of the algae showed that they consisted mainly of Chlorella vulgaris, Chlorella pyrenoidosa and various slime-forming strains. Chlorination successfully controlled the bacteria in the circulating water, and the bacterial count was reduced from 1 8 /ml to 1 3 /ml. In an attempt to control the growth, the chlorine treatment was supplemented by the addition of a quaternary ammonium compound. The dose level of the free chlorine was reduced from 1 mg/l to 2 mg/l and up to 25 mg/l (solids) of a quaternary ammonium compound was added to the system water twice a week. Again, the bacterial levels were reduced, but the algal growth was unaffected. As well as being ineffective, the quaternary ammonium compound caused serious foaming problems in the system water. The information contained in this product sheet is based on data available to Bio-Lab Inc., and is thought to be correct. Since Bio-Lab, Inc,

4 The foam and algal growth circulating around the system blocked the heat exchangers and fouled the pump impellers, which led to overheating of the heat transfer surfaces in the forming equipment and the compressors, with consequent loss of production. To minimise the problems caused by algal deposition in the system a filter was placed in the outlet from the cooling pond, but this required regular cleaning, and an operator was employed from January to November to keep it free from algal deposits. It was decided that this measure was not satisfactory and could only be considered as a short-term solution to the problem. The Treatment The trial with Bellacide 325 was carried out in two stages. Cleaning stage (2 weeks) Day 1: 6 mg/l of Bellacide 325 (product) was added to the system water and allowed to disperse completely before sodium hypochlorite was added to give 3 mg/l free chlorine in the system water. Day 3: Sodium hypochlorite was added to give 3 mg/l free chlorine in the system water. Day 5: Sodium hypochlorite was added to give 3 mg/l free chlorine in the system water. Day 7: 3 mg/l of Bellacide 325 was added to the system water and allowed to disperse completely before sodium hypochlorite was added to give 3 mg/l free chlorine in the system water Figure 1: Results Time (days) The conditions in the cooling system improved and at the normal maintenance dose level the system was kept free from biological fouling. Manual cleaning of the filter in the pond outlet was no longer necessary and production losses due to overheating and machine failure were reduced to an acceptable level. The use of Bellacide 325 and chlorine was a complete success in controlling the biological fouling in the cooling system of this aluminium plant. Bellacide 325 and chlorine were particularly effective in removing persistent algal strains which could not be cleared with other algicides. Lower doses of Bellacide 325 and chlorine then maintained the system in a clean condition. Apart from the cost savings resulting from the reduction plant downtime savings in labour costs alone more than paid for the cost of the treatment. Following the successful trial, the combination of Bellacide 325 and chlorine was adopted as the routine treatment and it has given excellent results ever since. This procedure was repeated for a second week. Throughout the cleaning period the purge from the system was increased to remove the dead algae from the circulating water. The addition of Bellacide 325 at first caused a slight turbidity in the system water but this cleared immediately after the Bellacide 325 had been thoroughly dispersed and circulated round the system. After four days treatment the water became clearer and the bright green colour in the circulating water was not as intense. At the end of the cleaning programme almost all the algal deposits on the walls of the ponds and the cooling tower sections had been removed. Routine Treatment Routine treatment was started immediately after the completion of the cleaning programme. Bellacide 325 (2 mg/l product) was added to the system once a week and sodium hypochlorite was dosed to the circulating water to maintain 1 mg/l free chlorine. Figure 1 shows the concentration of Bellacide 325 (HPLC method) maintained in the system water using this treatment programme. Treatment Of Cooling Systems In A Major Chemical Plant The System The plant is a major site for the production of ammonia, sulphuric acid, urea, acrylonitrile and related products. There are nine major cooling systems with a daily make-up rate of 6.6 m gallons of river water. The subtropical climate (summer temperatures o F, winter temperatures 5-72 o F) and prolonged sunshine result in algal growth throughout the whole year. The problem Problems due to algal growth were minimised by continuous bromination to maintain a free bromine level of.5 mg/l. Despite this treatment the systems still experienced algal growth sufficient to cause operational difficulties. Various algicide treatments were tried including: The information contained in this product sheet is based on data available to Bio-Lab Inc., and is thought to be correct. Since Bio-Lab, Inc,

5 Quats: These were unsuccessful and gave foaming problems Quats + TBTO: These were unsuccessful and solubility problems were encountered with TBTO. High level Cl 2 and biodispersant: These were partially successful Isothiazolone: These were partially successful. Volume (gallons) ph Treatment Algal growth The treatment System 1 Utilities plant all organic deposit control regime + biodispersant + continuous bromination + occasional dosing of proprietary algicides large areas of top deck covered with ¼ inch layer of algae System 2 Methylmethacrylate plant (acid dosed system) Zinc/phosphate/ phosphonate regime + biodispersant + continuous bromination some areas of top deck covered with 1 / 8 1 / 4 inch algal film In an effort to rectify operational difficulties, Bellacide 325 was selected for trial. The biocide treatment in these systems (systems 1 and 2) was replaced with Bellacide 325 in conjunction with the previous bromination regime, dosed to maintain 3-4 mg/l product for the first 4 weeks of the trial and then reduced to maintain only 1 mg/l product. Prior to the trial, some areas of the top decks were manually cleaned. Results The addition of Bellacide 325 resulted in no algal growth, either on the areas manually cleaned or on areas with existing deposits. Furthermore, laboratory tests on water samples taken from the system confirmed no algal growth, even when incubated under ideal growth conditions. In contrast, all other systems on this site not using Bellacide 325, experienced algal growth. The existing algal deposits in the systems treated with Bellacide 325 were also slowly reduced in area and thickness over the course of the treatment. No operational difficulties due to foaming, incompatibility with other water treatment products, handling problems, blockage of pipework by sudden release of algal deposits etc. occurred during the course of the trial. This confirmed the excellent algal control properties of Bellacide 325 used in conjunction with low level bromination. Conclusion These two case histories have shown the excellent properties of Bellacide 325 in preventing any new algal growth and in removing existing algal deposits in systems treated with a low level of free halogen. The following are trademarks of BioLab, Inc.:- Bellacide, Belcor, BioLab Logo, Waterfront Logo Registered US Patent and Trademark Office 2 BioLab, Inc. All rights reserved. Tenax Road, Trafford Park PO Box 1489 Manchester Decatur M17 1WT GA United Kingdom USA Telephone (44) Telephone (1) / Fax (44) Fax (1) Telex Visit our Website on The information contained in this product sheet is based on data available to Bio-Lab Inc., and is thought to be correct. Since Bio-Lab, Inc,