Optimization of WWTP at Maize Industry

We have opened our Waste Water Treatment reactor after 5-years of operation at maize industry because we were facing low pH issue at its outlet and higher COD at outlet than inlet. The reactor is made of concrete and has no agitation with upward flow. The lower portion of reactor is getting blocked with sludge in treatment process.  The plant capacity is of 30 m3/hour but we achieve only 5 m3/hour. Can anyone help us with streamline operations and inlet streams ration at equalisation tanks?  How do we optimize the treatment process to avoid filling the reactor with sludge again?