Technical discussion: What are the advantages and disadvantages of chemical and physical methods for circulating water treatment?

Disadvantages of chemical treatment: _ It is difficult to achieve the exact dosage; either too much or too little is used. _ Skilled personnel are required to add and mix the chemicals. _ The chemicals need to be added continuously, which is cumbersome. _ Unreacted chemicals cause corrosion and algae problems. _ The addition of chemicals increases conductivity, resulting in a lower concentration factor and significant water waste. _ In some countries or regions, the use of biocides is restricted (for example, in Japan). _ It cannot remove existing scale. _ It cannot effectively control chemical deposits, scale, and bacteria beneath biological films. _ It is not environmentally friendly. As for the advantages of chemical methods, I hope my seniors and peers can add to this discussion. In fact, I think that if physical methods can meet the required process conditions, there is no need to use chemical methods at all, which is also in line with the energy policy goals of certain industries. Currently, physical methods already achieve better results than chemical methods. My company has a system for removing and preventing scale using physical methods... I’m not trying to advertise; I just want to exchange ideas with my peers and improve together... as discussing this here might give the impression of advertising. I hope to communicate with seniors and peers on QQ; my QQ number is 609628320.

Let’s focus on the advantages of chemical methods: 1. Chemical methods enable rapid treatment of circulating water, with significant results. 2. It is easy to operate and simple to use, with no complicated addition process or excessive precautions. 3. It offers excellent performance: it takes into account not only scale prevention in the system but also corrosion inhibition, resulting in a satisfactory overall effect. 4. The operating cost is low, and the maintenance costs are also quite low. 5. Its advantages are more evident at high concentration ratios; the results are significant, and both the water-saving effect and equipment maintenance satisfy customers. Let’s also talk about the disadvantages of physical methods: 1. Physical methods, whether it’s ion rods, magnetism, or low-voltage electric fields, all have their limitations. For example, in very large systems with high SS levels, there are scaling types such as calcium phosphate and calcium sulfate in addition to calcium carbonate; moreover, due to the different materials used, corrosion problems are extremely severe ； In addition to algae, there are also fungi and various types of bacteria, etc. How can physical methods take care of all of them? The advantage of chemical methods is that different formulas can be developed according to various situations, allowing for tailored solutions; in comparison, physical methods are less effective than chemical methods. 2. Additionally, physical methods must be implemented through equipment, and the location where these devices are installed is extremely important; as a result, there are inevitably limitations. 3. There are few examples of physical treatment methods, especially with regard to large-scale industrial circulating water systems; cases related to small circulating water systems are not sufficient to illustrate the situation.

This post was last edited by cdpulin on 2010-1-6 at 10:52. The comments from the moderator were very helpful to me; I also conducted a detailed analysis. I hope the moderator won’t mind – after all, truth can only be established through clear reasoning. Hehe. In physical therapy, there are things like ion rods, high and low frequency electromagnetic waves, high and low voltage electrostatic fields, as well as nanometal source technology, among others. It originated in the 1960s; at first, there were issues of instability, a common problem that arises with every new technology. However, after several decades of development, these technologies have become more mature. In the case of electromagnetic wave applications, it was found that lower frequency waves are more effective than higher frequency waves. When it comes to nanometal choices, silver proved to be more effective than copper. The combination of electromagnetic waves and nanometal technologies, as well as the use of various types of nanometals, represent optimal solutions that have been identified through technological development. For these advantages to be fully realized, specialized patented technologies are also needed. There are many successful examples of the physical method being used in large-scale circulating water systems. Abroad, companies such as Apple Computer, STMicroelectronics, Panasonic, and Epson Industrial Co., Ltd. use electromagnetic wave technology for scale prevention and removal. In China, sites like Taiyuan Steel Plant and Dalate Power Plant also employ this technology. In my opinion, the most important aspects in the application of the physical method are the supplier’s technical expertise, understanding of its application, after-sales service, and communication with the manufacturers. Of course, I’m not saying that the physical method has no shortcomings at all. For example, high concentrations of silicates and chlorides affect the concentration ratio, while electromagnetic waves and electric static fields have little effect on water that is too soft; however, these process conditions can usually be adjusted by most manufacturers. Adjustments can also be made accordingly in terms of the technology provided. Therefore, communication is very important. As the moderator mentioned, number 3: it offers good performance; it takes into account not only the system’s scale prevention but also corrosion inhibition, resulting in a satisfactory overall effect. In addition to its scale-removal function, the physical method also causes black rust to form on materials such as stainless steel, thereby providing a protective effect; its side effects are far fewer compared to the chemical method. 4. The operating cost is low, and the maintenance costs are also quite low. I can’t agree with this. I’m aware of several chlor-alkali plants in Henan; their annual expenses for chemicals amount to millions. For larger closed-loop water systems, I think the cost of chemicals should also be in the hundreds of thousands, right? Of course, this doesn’t apply to those special plants that don’t use chemicals at all. Is that considered low cost? Physical methods incur low costs or no costs at all. 5. Its advantages are more evident at high concentration ratios; the results are significant, and both the water-saving effect and equipment maintenance satisfy customers. Apart from environmental considerations, another important reason why physical methods are used is that they enable an increase in the concentration factor, help save water, improve heat exchange efficiency, and reduce energy consumption. There may be some aspects that have not been considered thoroughly; I hope my fellow students can point them out... In short, I really want to exchange ideas with my seniors and juniors in order to improve together.

This post was last edited by hesonchang214 on 2009-8-7 06:55. Two years of chemical treatment have done nothing. It was originally supposed to last a year, but the performance was poor; the other party requested further improvements, including the addition of a secondary filter, yet the performance remained unsatisfactory.

This post was last edited by hesonchang214 on 2009-8-7 06:54. Thank you to the person who shared it above. I’m not very familiar with physical methods, but I am well aware of the disadvantages of chemical methods.

Treatment by combining physical and chemical methods.

To be honest, when it comes to familiarity with the recirculating water process, my classmates are definitely my teachers. However, from what I know and have experienced, those who opt for physical methods usually do so because they are dissatisfied with chemical methods (in fact, chemical methods can work well too, but there are many factors involved such as the skills of the manufacturers’ staff, the formulas provided by suppliers, and after-sales service. It’s necessary to integrate these various factors into a highly effective combination; otherwise, many problems will arise, resulting in wasted money with no satisfactory results). Another issue is the requirement to save water and reduce consumption – generally, the concentration ratio in China is 2–3, while in some foreign countries it can reach 7–8, showing an obvious difference. Of course, if a supplier of physical method equipment fails to deliver satisfactory results, it doesn’t mean that all suppliers of such equipment are ineffective; we shouldn’t generalize. What’s most important is whether the equipment supplier has strong technical capabilities for integration, good skills in combining different processes, and excellent after-sales service. There are many issues that seem unsolvable using physical methods, but in reality they can be resolved, so communication between both parties is very important. It’s true that I’ve mentioned so many advantages of physical methods, partly because I’m confident as a supplier of such equipment, but that’s just a little bit; most of it comes from my own experiences. With that said, I’d like to remind everyone that although physical methods are good, they’re not a panacea. If you have any questions or want to discuss anything, feel free to communicate in advance...

Everyone has spoken very well; each technology has its advantages and disadvantages, as well as its areas of application. To objectively assess the advantages and disadvantages of physical and chemical methods, it is possible to leverage their strengths by combining them; for example, by using chemicals alongside physical filtration processes. This approach not only helps to reduce the amount of chemicals needed, as well as wastewater and water replenishment requirements, but also minimizes the loss of chemicals through wastewater discharge. At the same time, it increases the concentration ratio.

Using a bypass flow? In a broad sense, it is also a physical method... but we shouldn’t limit ourselves to that. Please think carefully about the original intention behind designing a bypass system; that way you will have a better understanding.

Regarding the concentration ratio, a level of 4 to 5 is quite good; increasing it further doesn’t offer much benefit in terms of water conservation. At best, it’s just a way to hype up the concept of concentration ratio. Sinopec’s standard requires a concentration ratio of 5. When the concentration ratio is increased to a relatively high level, there is a greater tendency to scaling. To prevent this, new treatment equipment or chemicals (such as acids) have to be added, and the costs may not be lower than those associated with concentrating the solution to 5%, or they could even be higher. Physical and chemical methods each have their own advantages, and they coexist without one eliminating the other; this shows that they are not meant to replace one another. It is simply the case that in certain situations, one treatment method is more suitable, depending on the actual process requirements. The many complaints regarding chemical treatment methods are mainly due to management issues. In a recirculating water system, 30% comes from the chemicals used and 70% from proper management; without effective management, even the best chemicals are of no use.