You might try Purac over in Sweden or England. They used to have the experience to do this. I worked with them a long time ago in the US.
Most municipal wastewater is going to have ammonia, phosphorus, nitrogen, BOD, COD, and TOC. The level of treatment that you will be required to do depends on the extent of the existing treatment at the municipal plant.
If the municipal plant is not doing extensive treatment of the wastewater (called "advanced treatment"

, then you will have to put a biological process in to remove the ammonia, phosphorus, nitrogen, and BOD/DOC. The effluent from the biological treatment is commonly lime softened in order to further remove contaminants. You will also have to chlorinate and then filter the effluent to remove the suspended solids. Hopefully the TOC will be low so you do not have to try to remove it. You will also have have to have some type of solids dewatering process for the solids generated in the treatment process.
Once you have done all of the above, the water will be suitable for treatment in your existing system. Treatment of municipal wastewater for reuse is a lot more complicated than what you are doing right now.
I have some experience in the power industry so if you need further assistance, let me know.