6 july 2018


Rising to the challenges of a difficult pharmaceutical wastewater

The client
JSC Grindeks is the leading pharmaceutical company in the Baltic states, based in Riga, Latvia.
The needs
The wastewater from the production plant is highly polluted and contains difficult-to- degrade and toxic organic compounds (including phenols). High organically bound nitrogen concentration is just one challenge of this wastewater. The requirement was to build a new, compact, and efficient wastewater treatment plant and comply with regulations
for discharge to the municipal treatment plant for chemical oxygen demand, total nitrogen, total phosphorous and suspended solids.
The solution

AnoxKaldnes, a subsidiary of Veolia Water Technologies, began the project in the laboratory through feasibility studies and for the optimization of the process design of the MBBR technology. The laboratory trials helped to identify the maximum concentration of toxic compounds that could be fed to the biological process without interfering with the treatment processes. A “toxic” tank for storage of the effluents rich in toxic compounds was proposed as part of the solution. The effluent stored in the toxic tank was designed to be slowly fed to the biological treatment without exceeding a maximum allowed concentration.
The results
The first MBBR reactor is primarily for the reduction of COD. About 60-70% of the COD is removed in this reactor with the final effluent COD removal typically over 90%. The second MBBR reactor is used for reduction of large molecules that are a waste unique to the production of certain pharmaceuticals. Reactor three continues the removal of hard to reduce organic compounds. The three upstream reactors act as a buffer ahead of reactor 4 where nitrification takes place. The final reactor is a post-denitrification reactor where solvents from the production process are utilized as an effective carbon source.
Total nitrogen treatment efficiency varies between 45-88%. Nitrification is the most sensitive step of the process treatment and it is periodically upset during production stops and when disinfectants are used for cleaning. The average phosphorous concentration in effluent is usually around 2 mg/l. Wastewater containing phenols are pumped to a buffer tank with controlled flow rate so that phenol concentration in the buffer tank is 20-30 mg/l and in effluent phenol concentration do not exceed 0,8 mg/l.
Grindeks MBBR