When you say, "industrial park", I assume you mean a variety of manufacturing and/or processing activities are conducted in the complex. Sometimes the label industrial park is just a generic phrase for essentially a business park - which is a whole different game.
You will need a comprehensive influent sampling program before you even get started - not just a few grab samples. Also, be sure to examine the types of chemicals that are being used in the industrial park. Industrial wastes cannot be easily defined like domestic sewage. In some cases it may be more efficient to find alternative methods of disposing of some nasty, hard to treat, chemical wastes at the source. Pretreatment may also be an option. In so far as possible, you want to reduce the array of exotic chemicals that are introduced into the waste stream.
Most likely you will be looking at physical and chemical treatment methods designed to strip out pollutants introduced into the waste stream. Chemical coagulation and flocculation plus filtration will likely be part of the treatment process. Biological treatment methods will only work if you have a significant amount of organic wastes; otherwise you may be looking at chemical oxidation to meet your effluent limits.
Again, the key is to fully understand the character of the waste stream - only then can you set about proposing treatment schemes.