Civil Engineer here with a little background in water/wastewater, I doubt that wall will have any affect on the smell. Once those particles become an aerosol through various means they are just intermixed in the ambient air. Until they become diluted beyond the detection level of the average nose, there isn't much you can do about it. If the park was down wind of the wall, that wall would actually create a low pressure zone behind it brining the air down behind the wall much like the low pressure zone in the bed of a truck traveling down the highway.
Stopping the smell at the source is the only real way to reduce the smell. Never dealt with that particular aspect, but I do know there are ways to cut those odors in the treatment process.
Either that, or set up some big fans to change localized weather patterns, whichever is cheaper. /s