A device for the treatment of technological wastewater from the production plant of corrugated cardboard in 2018. was delivered. This supplied device ensures the quality of treated water in accordance with the Pravilnik o graničnim vrijednostima emisija otpadnih voda (NN 20/2013; 43/2014; 27/2015 and NN 3/2016).
The input daily amount of water is 10 m3, and the maximum maximum flow is 2 m3/h.
| RB. | PARAMETER | UNIT | RESULT |
| 1 | BOD | mgO2/l | 17 588 |
| 2 | COD | mgO2/l | 32 554 |
| 3 | Oil and fats | mg/l | 35,2 |
| 4 | Total hxdrocarbons | mg/l | < 0,10 |
| 5 | Barium (Ba) | mg/l | 0,300 |
| 6 | Borium (B) | mg/l | 3,00 |
| 7 | Chrom (VI) | mg/l | < 0,010 |
| 8 | Sulphites | mg/l | < 0,100 |
| 9 | Sulphates | mg/l | 1420 |
| 10 | Total nitrogen | mg/l | 91,6 |
| 11 | Ammonia | mg/l | 9,05 |
| 12 | Nitrates | mg/l | 101 |
| 13 | Nitrites | mg/l | 20,4 |
Table 10. Input parameters of technological wastewater that needed to be treated
Based on the data on the results of technological wastewater, the technology of the physico – chemical process of technological wastewater treatment was selected.
The technology consists of an equalization tank that serves to collect technological wastewater and prevent hydraulic shocks to the plant and equalize wastewater. The tank is equipped with an aeration and wastewater mixing system. This prevents the deposition of suspended particles in the pool and homogenizes the wastewater composition. The wastewater is then pumped into a physico-chemical reactor in which coagulant and flocculant are dosed via the dosing station (Figure 10.). Stirring in the reactor (Figure 11.) results in a chemical reaction during which sludge flakes are formed which, after switching off the mixing, settle to the bottom of the reactor.
Figure 10. Dosing pumps
Figure 11. Physico – chemical reactor
Figure 12. Activated carbon filter
The purified water is sent to the final activated carbon filter and discharged into the city sewer (Figure 12.).
The precipitated sludge is discharged into a sludge tank where it is collected and then sent to a filter press. Using a filter press, the sludge is dehydrated to obtain a sludge with 20-30% dry matter. After dehydration, the sludge is disposed of in accordance with the law.
The device is located in a steel container together with an electrical control cabinet that automatically controls the operation of the entire device and is equipped with an audible and visual alarm.
