The device for treatment of technological wastewater, flow of 42 m3/day and municipal wastewater was delivered in 2017. Technological wastewater is generated during slaughter and meat processing.
Inlet water parameters, shown in Table 1, did not meet the values for water discharge into the Vrbas river.
| No. | PARAMETER | UNIT | VALUE | LIMIT |
| 1. | COD | mgO2/l | 630 | 125 |
| 2. | BOD5 | mgO2/l | 360 | 25 |
| 3. | pH value | – | 8,3 | 6,5 – 9,0 |
| 4. | Alkali | g CaC03/m3 | 385 | |
| 5. | Electrical conductivity | µS/cm | 1210 | |
| 6. | Total nitrogen | g/m3 N | 15,5 | 15 |
| 7. | Total phosphorus | g/m3 P | 2,8 | 3 |
| 8. | Iron | mg/m3 | 1080 | 2000 |
| 9. | Oil and fats | g/m3 | 380 | 20 |
| 10. | Settleability in 30 min. | ml/l | 0,3 | 0,5 |
Table 1. Parameters of technological watewater and required values for discharge in river
Based on the input parameters, DAF technology with a combination of biological treatment, SBR (Sequencing Batch Reactor) was selected for the treatment of technological wastewater.
The DAF technology used is described in section 1.1.1. of these list. The difference is in the capacity of the device, which is smaller at this location, 42 m3/day.
After purification, the water is transferred to a biological treatment plant based on SBR technology (Sequencing batch rector).
The biological treatment plant is divided into two functional parts: the wastewater intake section and the SBR reactor. The wastewater receiving part serves as a buffer for a certain volume of wastewater (batch) before treatment in a biological treatment plant.
The SBR reactor consists of a single chamber and aerobic biodegradation of waste materials by activated sludge. The tank is filled and emptied using air-lift pumps.
The control unit is programmed to perform a water purification cycle in four main phases.
Normal cycle:
These four phases form one wastewater treatment cycle. By default, one purification cycle lasts about 8 hours.
Excess activated sludge from the biological reactor as well as sludge from chemical treatment is transferred to the sludge tank. The sludge from the tank goes for further treatment using a screw dehydrator where a dehydrated sludge with 18 – 25% dry matter is obtained. Dehydrated sludge can be transported from the WWTP in accordance with regulations and local laws, to an appropriate landfill or can be used as fertilizer on agricultural land.
