So when we look at manufacturing industries across the board, 很多人计划扩张和生产, 比如增加新的生产线，增加生产时间, and that puts an extra strain on their wastewater systems. We want to future-proof our wastewater systems so that when we do those manufacturing increases, we don’t have to worry later down the line about if our wastewater system can safely handle that increase in volume.
Why should manufacturers be looking at future-proofing their systems?
A manufacturing plant never plans on decreasing its volume, 但不幸的是, 有时确实会发生, so we have to prepare for that as well if we see that as a trend. 但在大多数情况下, people plan on expansion; they plan on growing their business and growing their production activities, so we just want to help businesses and manufacturers understand that there is a thought process that needs to be associated with wastewater systems. 很多时候, 我们将看到一个制造商建立一个全新的设施, 或者加一条电镀线, 而且根本不包括废水, 这会引发一系列完全不同的问题.
What does a manufacturer need to look at to ensure their wastewater is prepared for expansion?
When you look at the volume of wastewater that you’re going to be running through your wastewater system, you want to make sure that your tanks are sized appropriately and that you have enough storage to hold a minimum of four hours’ run time. A lot of people try to go for a 24 hour run time; if possible, it is not always possible; some plants manufacture a lot more wastewater than others. But you want holding capabilities; you want your tanks to be large enough to have a dwell time of at least 15 minutes in each tank that is actually processing the wastewater — not your holding tanks, 还有你的pH调节罐, 你的化学添加罐, 还有你的絮凝池. 你至少需要15分钟, so you need to make sure your tanks are sized appropriately for that, and you want to make sure that your pumps are large enough to handle the transfers. 如果你的坦克重力相互作用, make sure that that the increase in flow want won’t flood those tanks, that the gravity feed connections are adequate enough to handle an increased inflow. You want to make sure that your chemical feed pumps are properly sized so that you can dial up your chemistry or dial down your chemistry as needed. You also want to make sure that they’re not oversized because if they’re oversized, you might not be able to dial down if you need to on your slower shifts. You will also want to make sure that your dewatering equipment — whether it’s a vacuum drum filter or plate and frame filter press — is adequately sized to handle the number of solids that you’ll produce.
氢氧根沉淀是如何发生的?
Most of the metal finishing world uses hydroxide precipitation as a way to remove their metals. Hydroxide precipitation is simply when you add sodium-potassium, 氢氧钙, 或氢氧化, 其实是任何形式的氢氧根, 来调整你的pH值. The hydroxide forms bonds with the metals and removes them from your wastewater in the form of metal salts, 这就是固体的生成. There is actually a hydroxide solubility curve chart that if there is no chelation present — or very minimal chelation present — in your wastewater system, you can use that curve chart as kind of a guide to where you need to target your pH to remove the metals that you have in your system.
Are there other ways to remove metals than precipitation?
A lot of what we hear now is things like electrocoagulation, which isn’t very well known in the metal finishing world. Electrocoagulation is not electrowinning; it is a different process, 但它能让你克服螯合因子. I have seen it used in places where accelerated mass finishing, 哪个是螯合重的过程, 是否与电镀冲洗液混在一起. It allows for metal removal even with the chelation present. Electrocoagulation is a totally physical way of removing your metal contaminants; you can do ion exchange in some cases, 还有一种叫做硫化物沉淀, where you use a sulfide instead of a hydroxide to adjust your pH, and you can use those at a much lower pH than the hydroxide solubility works. 去除金属的方法有很多种.
How can a manufacturer ensure they are using the right chemistry for their wastewater system?
你通常会做我们所说的“系统福利检查”,’ where you want to get some of your wastewater prior to any treatment being done to it, and you want a bench test using what your current chemistry is and the dosing that you’re currently dosing at to see what you’re removing. Before bench testing, you want to see what you actually have in your wastewater. 这些年来有什么变化吗? Have you added a new line that put a new contaminant in there that wasn’t in there before? It is so that you can gauge your metal removal efficiencies; if you’re hitting above 90% metal removal, 你做得很好, 而且你的化学品使用量很低, 那你的治疗方案就对了. But say your chemical usage has crept up over the years, you’re now at 10-15 mils per gallon to treat with your coagulant; it might be time to bring in a different form of coagulation. 在我们这个行业, there are four types of coagulates: there’s iron-based, aluminum-based, 钙基, and a new one on the market is rare-earth-based coagulate. 所以比较一下，看看哪个更好.
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