I am handling a pharmaceutical wastewater treatment plant which uses activated sludge treatment followed by MBR.
The wastewater has COD ranging from 200 to 300 gpm on average and it needs to be reduced to < 30 mg/l - 100 mg/l.
I am screening various AOP' s (advanced oxidation process) and other BAT's (best available technologies) for reducing the COD from the waste water.
I am investigating some alternative options such as:
Ozone/Perozone
UV Peroxide
Activated Carbon
Resins
RO
Ultrasonic
AOP followed by a fluidized bed reactor ( FBR)
Wet Air Oxidation
Are there any other methods that are worth screening or does someone have experience with similar (pharmaceutical) wastewater and COD removal to very low levels?
Hi Asher, Arvia combines the advantages of adsorption and advanced oxidation with its Organics Destruction Cell. It could provide the reduction you need in a single step. The ODC has recently treated some pharmaceutical wastewater for polishing COD. The client also had some particular pharmaceutical compounds they needed to show 80% removal of, so we have been able to tackle this as well. Please get in touch if you'd like to learn more about it. I would certainly be interested to discuss your wastewater problem in more detail.
We have our own technology which is called OFR and we manage to reduce the COD to less than 30 mg/l. Our reactors produces Hydroxel Radicals that oxidize the contaminant under normal temperature and pressure. We don't use chemicals in our process. we treated waste water with COD exceeding 1800 mg/l
You might also want to consider UV with titanium dioxide, or electrolytic oxidation (see http://www.arviatechnology.com/). (Please note: I have no link to Arvia and this should not be interpreted as an endorsement, but it is an interesting technology!)
The best method for your application will be dependent on the nature of the pharmaceutical effluent, the volume and (importantly!) the variability of the effluent. One method may work for one compound, but if the upstream factory begins production of a different pharmaceutical, removal may be very different! Look at typical constituents in the effluent after biological treatment and how much needs to be removed. Methods like RO, AC and resins are unlikely to be economical for large quantities, unless there's a high value to recycling water via RO. For large quantities, you'll probably want to focus on oxidation methods and ozone is NOT the "only guaranteed method"!
The only guaranteed method to reduce COD by at least 90% is OZON. Ozon has no residual effect (usually) but any excess ozon must be destructed or the treated wastewater must be stored for a certain period of time (max 24 hrs) so the ozon will revert to molecular oxygene. The whole process can be monitored by measuring either the ORP or the residual ozone.
If you allpy an ozonation unit downstream of the biological unit and recycle back the ozonate effluent you may get substantial removal. See
Valeria Mezzanotte , Roberto Canziani , Elisabetta Sardi & Lorenzo Spada (2005) Removal of Pesticides by a Combined Ozonation/Attached Biomass Process Sequence, Ozone: Science & Engineering, 27:4, 327-331, DOI: 10.1080/01919510591008362
Keisuke Ikehata , Naeimeh Jodeiri Naghashkar & Mohamed Gamal El-Din (2006) Degradation of Aqueous Pharmaceuticals by Ozonation and Advanced Oxidation Processes: A Review, Ozone: Science & Engineering, 28:6, 353-414, DOI: 10.1080/01919510600985937
You havent considered any anaerobic digestion technology.
Primarily, I feel that incorporation of a pre-aeration anaerobic digester can significantly help you in achieving the desired norms. The RO and other membrane technologies again result in high end reject wastewaters, the disposal of which is again an issue.
Anaerobic phase can help in reduction of the organic load without any significant electrical energy addition. Also, the reduction efficiency of this reactor can reduce the load on the further units, as well as, provide a source of fuel gas, which can be used for gas generation. The organic load you have is high, so gas generation will be significant as well. The calculation is
{(FLOW*ORG.LOAD [COD]) / 1000} x 0.5 x 0.45
Here, 0.5 is the percentage of COD Reduction (50%), 0.45 is methane content of this gas (45%)
Further, thumb rule suggests that 12000 m3 of methane generates 1MW electricity.