【Process Discussion】: Treatment Processes for Suspended Solids (SS) in Wastewater
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This post was last edited by *lihuagong on 2017-5-27 at 13:56. Here we go again with the series of discussions on manufacturing processes, featuring small cases from our everyday environment~ [Case Description] The wastewater treatment process in the factory is as follows: For the simplest type of inorganic wastewater treatment, after acid-base neutralization, the wastewater is transferred from the original tank to a pH adjustment tank; inorganic flocculants are added thereafter, and the mixture then enters an aggregation tank where polymer flocculants are added. Finally, the wastewater settles in a sedimentation tank. The upper supernatant is discharged directly to the wastewater treatment plant, while the bottom sludge is sent for plate and frame filtration. 【Problem】 Based on the suspended solids SS in the supernatant of the current sedimentation tank, it is generally around 100 mg/L (the previous **wastewater discharge standard was below 400 mg/L). But as environmental emission standards become stricter, requiring the SS content to be below 30mg/L, what methods do you guys have? ? Everyone is welcome to participate actively in the discussions; high-quality replies will be rewarded~ @arpcd @DesertFish @longkui1990 @LuoMi @Pingsha @tdl522 ************************************************************************************************************** Finally, everyone is invited to subscribe to Taopost’s album – the series of case studies on \"Craft Discussions\" – as well as to download HaiChuan’s interactive e-book on the same topic.
We have also encountered such a problem in our design: it is difficult to remove suspended solids from phenol-ammonia wastewater, especially those with a size of less than 10 μm.
A flowchart drawn by a little Japanese kid? ? Settling tank: Lol, it seems that in ancient Chinese, “Shen” and “Chen” have the same pronunciation. Those particles of yours that don’t settle can basically be considered to be very small in size. The reason they don’t settle is due to insufficient settling time; in other words, the tank is suitable for larger particles but not for smaller ones, as its vertical height is too short. There are actually just two solutions to this problem: 1. Add efficient settling aids to the settling tank, such as inclined tubes or plates, to reduce the settling distance. As long as there’s enough time for them to stay there, even small particles can settle. Lol 2. Modifying the settling tank is quite complicated; another option is to use several high-efficiency filters before sending the wastewater to the treatment center. Choosing the right filter elements is key. Good sintered filters are quite expensive; you can ask the little Japanese guy for advice on this. . . 3. Try replacing the polymer flocculant and selecting a better one in terms of charge properties; this is a delicate task that presents considerable difficulties. The simplest solution would be to add a filtration system; the investment required for that might be high. Inclined tubes and plates don’t cost much, but their effectiveness is likely inferior to that of a filtration system.
Bro Dao, you’re really amazing~ This diagram was drawn by those little Japanese guys; I took the easy way out and just copied it~~ As for the settling time, with a wastewater flow rate of 30 m3/h and a sedimentation tank capacity of 190 m3, 6 hours should be more than enough. It’s likely that the suspended particles in our wastewater are mainly silicon dioxide, and these small particles cannot continue to settle and be removed. My initial idea was also to simply add a filter, but I wasn’t sure which filter to use. I wanted to determine the particle size distribution in the wastewater, but it wasn’t possible to do so due to the low concentration. For now, the only option is to contact a few environmental protection companies to conduct experiments and give it a try. The approach should be to start with filters or coagulants.
If it’s SiO2 particles, then congratulations first – it’s very difficult. This damned stuff carries a negative charge, so it’s necessary to find something with a positive charge to counteract it, such as cationic polyacrylamide flocculants. . Have the environmental protection company conduct an electrophoresis test. . It is still recommended to opt for filtration; among precision filters, 3M filters are more than sufficient. There are certain considerations when it comes to filtration systems, and their price is a bit high. . .