Treatment Methods for Pharmaceuticals Wastewater

sequencing batch reactorWastewater from pharmaceutical industry poses one the biggest challenge to the industrial waste treatment system because there is no single approach or treatment method that applies the same to all. Generally depending on what type of chemicals that are used in the manufacturing processes, the COD value can vary considerably from as low as 100ppm up to 10000ppm with some even more than that. Moreover because most pharmaceutical products have proprietary chemical composition, researchers have not been able to gather sufficient information to be used as a guideline applicable for all companies.

To make a broad generalization, wastewater from this industry mostly contains metal compounds originating from catalyst (organic and non-organic in nature), equipment packing like hplc and that includes solvents as well such as IPA (isopropyl alcohol), ethanol and methanol. The wastewater can come from many streams originating from different stages of the production process. If those contain water soluble solvents, the COD value can reach as high as over the 10000ppm limit and that also depends on the level of contamination carry over to the water. Usually in order to deal with this problem, the high COD stream should never be directly fed to the treatment system but instead, the wastewater should be diluted in order to lower the COD. This is important to prevent sudden shock to the biological system.

Characteristics of the wastewater other than containing chemical compounds, will usually has very little to none suspended solid materials with presence of varying degree of organic composition. In line with these characteristics, choice of treatment processes that are selected will usually include the chemical precipitation as the first step which is part of the pre-treatment stage before the wastewater is fed to the biological process. As mentioned earlier, the chemical compound will be different in nature depending on what type of pharmaceutical products being produced and as such binding or chelating agents are used to attract and lump together most of the contaminants to be removed via floc formation. A more recent development is by using electrodialysis membrane system to separate chemical compounds based on these properties but however, cost is a major consideration here while this only works if incoming waste volume is low. Usually pH adjustments are also done during this step and it is very critical that this is carried out before the water is fed to the aeration pond as the optimal bacteria breakdown processes will require a certain working pH range from 6.5 to 7.5.

SBR or sequencing batch reactor is considered a normal standard approach adopted for almost all pharmaceuticals waste treatment. There are several logical explanations as to why it is selected and main reason is because of the space constraint and the fact also is that most of the pharmaceutical manufacturing processes are not running 24 hours with low volume of wastewater generated. As such when the manufacturing facility is shut down for the day that is when the treatment phase in the SBR will take place. However, in larger pharmaceutical plants whereby the processes are running continuously non stop, that is when the SBR has to be constructed with having two or more different reactors running alternately. Among the other waste treatment facility needed to handle the incoming stream also includes sludge filter press for dewatering purposes. This is important as dead sludge is continuously removed from the biological system.

Challenges facing the smooth running and operation of the pharmaceutical waste treatment system mainly revolve around the issue of inconsistency. As explained earlier, the influent COD value can fluctuate considerably and as such mixing tanks are usually constructed to blend wastewater from different streams prior to feeding to the biological system. Another potential problem is related to presence of chemical inhibitors which becomes like a toxin/poison that disrupts the biological function of the bacteria. Most of the time, poisonous wastewater stream can almost wipe out and kill the old bacteria and thus the system has to be restarted all over again resulting in formation of young sludge which can then lead to bulking problem. As such, close monitoring on the dissolved oxygen concentration can give you an indication on how well the system is operating and observation on the formation of foam can also tell you on whether all these are young sludge.

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