Best Technology for Treating Abattoir Wastewater Before Discharging Into the System

I am monitoring industries which slaughter 15000 cattle, 500 sheep, 200 pigs per month. With the recommendation of the following standards: Determinants limits units  pH 5.7 - 8.4 pH COD 2380 - 8942 mg/l SS 189 - 3330 mg/l TDS 595 - 2805 mg/l TKN 0.71 - 24 mg/l       Always when I receive results from the abattoir, the results show noncompliance to all determinants except pH and TDS. At abattoir, we are using pre-treatment such as caustic, three phases such as primary, secondary and tertiary treatment but final effluent does not comply with the standards. All of the waste from the cattle, sheep and pig are taken out.  My question was: What is the best methods of reducing TNK to a required limit?  What is required to ensure that all of the determinants are complying? Does too much slaughtering have effects on some of the parameters?