As we always say in Anthroserv, “there is no wastewater treatment technology that fits all.” You may hear from different technology providers that their technology is the best among the rest, but environmental engineering principles state otherwise. The end-of-pipe techniques for wastewater treatment are usually composed of various technologies classified under either preliminary, primary, secondary, or tertiary treatment. Arranging them in sequence depend on the type of wastewater and the desired effluent water quality. You can think of it as puzzle pieces that need to merge depending on the photo intended.

 

From the four stages of treatment, the heart of the process lies within the secondary treatment. This is the stage where most of the pollutants (e.g. BOD, COD, TSS, nutrients) are removed. Secondary treatment technologies are usually biological in nature. Generally, these processes can be either suspended growth reactors, attached growth reactors, or advanced oxidation processes (AOP). Each general type is with their own share of advantages & disadvantages.

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Common technologies under the suspended growth reactors are Conventional Activated Sludge (CAS) and Sequencing Batch Reactor (SBR). The primary workers in these processes are the microorganisms we call Activated Sludge. The activated sludge is responsible in converting pollutants from its dissolved form (i.e. BOD, Ammonia) to its gaseous forms (i.e. Carbon Dioxide, Nitrogen Gas), which are released to the atmosphere. Be careful in the notion that that these technologies cannot pass the new DAO 2016-08 & DAO 2021-19 standards. They can. Just like we said earlier, it takes a tweaking in the puzzle pieces of CAS and SBR to allow it to remove Ammonia, Nitrates, and Phosphates.

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Suspended growth reactors are the most common technologies in the market. Numerous scientific and industrial studies have been conducted with them. These technologies are tried and tested. However, certain limitations, such as lot area, force us to look at other technologies, such as the attached growth reactors and AOP.

Under the attached growth reactors are the Moving Bed Biological Reactors (MBBR) and Membrane Bio Reactor (MBR). These technologies also use activated sludge, but they are attached to media or membranes, which increase their effective contact area. In turn, the required tank volumes become significantly lower. That is why they are the first options of technologies when designing for tight areas with large wastewater volume. Although, the trade-off of this compaction is higher capital and operational expenses. Media and membranes are quite costly and are relatively difficult to maintain. This also results to significantly higher energy requirements than CAS & SBR. Of course, with proper engineering, these technologies are also capable of passing the new standards.

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Lastly, AOPs are emerging technologies in the market. They are quite new, but very promising. The most common AOP we have right now are Ozone technologies. To date, there is no large capacity wastewater treatment plant yet that uses these technologies because of their complexities. They still need more research to prove their sustainability and scalability. And due to their novelty, their capital and operational costs are also higher than CAS & SBR but are at par with MBBR & MBR. Anthroserv realizes the potentials of AOP, which is why we are conducting our own research on such to make them sustainable and scalable.