Pulp and Paper Mill Waste Water Decolouration with Ozone Brendan van Wyk, Alexis Metais, Jens Gebhardt, Narain Madhaven

Pulp Mill Environmental Impact 2 The Pulp & Paper Industry generates large volumes of dark coloured effluents. The colour comes mostly from organic derivatives like lignin and other phenolic and resinous compounds, These are generally Non- Biodegradable and pass through secondary biological treatment processes. Coagulation and precipitation was the cheapest method of colour removal, however this results in a large volume of Toxic Sludge that needs to be disposed of.

CPCB published Effluent Discharge Limits 3 Main parameter Unit CODmg/L< 200 BODmg/L< 20 TSSmg/L< 30 ColourCPU< 150 TDSmg/L< 1800 AOXmg/L< 8 SARmg/L< 10

Treatment Options for Colour Removal 4 Bio Ozone Low COD No COD Limit COD Limit Bio Ozone Low COD Low COD Limit Bio Ozone High COD Low COD Limit Bio Ozone Bio Ozone Low COD

Case Study 1: Colour removal Indian Pulp Mill request for colour removal, while at least maintaining or reducing the COD and BOD of the effluent. Pre treatment conditions: Colour: 176 CPU COD: 182 mg/l BOD: 23 mg/l 5

Laboratory Set-Up 6 1.Oxygen supply (LOX, PSA or gas cylinder) 2.Ozone generator (WEDECO 8 HC. ozone capacity of 8 g/h) 3.Ozone analyzer for feed gas (BMT 964 C) 4.Venturi injector 5.Circulation pump (peristaltic or membrane) 6.Reaction column (glass reactor with a volume of 10l) 7.Sample point (ball valve) 8.Orbisphere measurement device (dissolved ozone) (not used) 9.pH-measurement device 10.Data logger 11.Ozone analyzer for off-gas (BMT 964 C) 12.Catalytic ozone destructor

Case Study 1 Results 7

8 Ozone Consumption (g/m 3 ) COD (mg/l) Colour (CPU) BOD 5 (mg/l)

CASE STUDY 2: COLOUR REMOVAL AND DISINFECTION The main objectives of the trial were: Disinfection Decolourisation Improved transmittance Using just 10g Ozone/m 3 the following results were obtained: A 2-Log reduction in Total coliforms was obtained Colour was reduced from 3.7 1/m to 2.0 1/m Transmitance was improved by 45.3% 9

Case Study3: Pilot Plant for Colour and COD removal 10 Decolorization for water reuse in white paper production COD reduction Achieve defined “medium” quality for re-use water

Case Study3: Pilot Plant for Colour and COD removal 11 Containerized system 1 kg O 3 /h production Pump-injection system 1.5 m³ reaction tank

12 Results Treatment Train 1 (Effluent 3FM)

13 Results Treatment Train 3 (Effluent MBR)

14 Results Pilot Tests Discoloration > 90 % Discoloration goes along with slight COD reduction COD reduction related to the applied ozone dosage 14 Achievements: < 50 mg/L COD in outflow feasible Colourless Outflow

15 Costs 15 Flow rate 3000 m³/d Ozone dose of 80 g/m³: Investment costs: 0.05 – 0.12 €/m³ Operation costs: 0.10 – 0.22 €/m³ Operational cost for ozone production 1 – 2 €/kg ozone, energy consumption: ~ 0.6 – 1.5 kW/m³ Costs are depending on amount of Ozone produced per hour, cost of oxygen and cost of power

16 Costs

17 Pilot Conclusions Discoloration is feasible and cost effective with Ozone Ozone enables a reduction in COD load Ozonation step has no influence on solids and salts, further treatment step necessary for high quality waters

Full Scale Case Study German Paper mill required to reduce specific effluent volume through recycling waste water. After testing, it was decided to install the following: Pressure disk filtration system 3kg/hr ozone generation system 2 reaction tanks (4.5m 3 each) Ozone injection system 18

Pressure filter and Ozone system 19

Plant Water Treatment Flow Sheet 20

Treatment Results 50% reduction in Fresh water consumption >90% Absorption of filterable substances Extensive decolourisation Water reuse for production purposes Reduction in specific water consumption 28m 3 / ton to 14 m 3 / ton of paper Investment Cost € Million Net annual Savings € 81,600 After depreciation and operating costs 21

Conclusions Ozone has proved to be very effective at colour removal from mill effluents Additional Benefits found are: Disinfection Improvement of BOD/COD ratio. This means that there is a total COD reduction after tertiary biological treatment Reduction in sludge generation if used in front of a DAF process Recycling of treated water back to process 22

Thank You For your Attention OZONE FOR A GREENER FUTURE