Emissions to Air

An integrated pulp and paper mill has a number of associated air emissions, arising mostly from operational processes and to a lesser extent from vehicle transport. Key point sources of air emissions at our mill include recovery boilers, power boilers, fibre lines, bleaching plant and lime kilns.

Recovery and power boilers are used to generate steam. These power seven steam turbines, generating 535MW of electricity. The recovery boiler, power boilers and lime kiln stacks are fitted with emissions abatement equipment in the form of electrostatic precipitators, to reduce the particulate loading of air emissions.

We have also installed continuous emissions monitoring (CEM) equipment at key emission sources. This provides a continuous set of data for our control rooms to review, while supplementing third party monitoring for regulatory reporting. Emissions-to-air monitoring is carried out quarterly by an approved third party testing company. The results are reported to regulators.

APRIL makes ongoing efforts to reduce emissions from the mill. These efforts include fitting of additional plant and equipment to recover by-products for use as fuel. The methanol recovery project mentioned in section 3.2 is an example.

APRIL’s pulp and paper mill conforms to the following EU Best Available Techniques for reducing emissions to air:

  1. Collection and incineration of concentrated malodorous gases and control of the resulting Sulphur Dioxide (SO) emissions. The strong gases can be burnt in the recovery boiler, in the lime kiln or a separate, low Nitrogen Oxides (NOx) furnace. The flue gases of the latter have a high concentration of SO2 that is recovered in a scrubber.

  2. Diluted malodorous gases from various sources are also collected and incinerated and the resulting SO2 controlled.

  3. Total Reduced Sulphides (TRS)emissions of the recovery boiler are mitigated by efficient combustion control and CO measurement;

  4. TRS emissions of the lime kiln are mitigated by controlling the excess oxygen, by using low-Sulphur fuel, and by controlling the residual soluble sodium in the lime mud fed to the kiln.

  5. The SO2 emissions from the recovery boilers are controlled by firing high dry solids concentration black liquor in the recovery boiler and/or by using a flue gas scrubber.

  6. BAT is furthering the control of NOx emissions from the recovery boiler (i.e. ensuring proper mixing and division of air in the boiler), lime kiln and from auxiliary boilers by controlling the firing conditions, and for new or altered installations also by appropriate design.

  7. SO2 emissions from auxiliary boilers are reduced by using bark, gas, low Sulphur oil and coal or controlling Sulphur emissions with a scrubber.

  8. Flue gases from recovery boilers, auxiliary boilers (in which other biofuels and/or fossil fuels are incinerated) and lime kiln are cleaned with efficient electrostatic precipitators to mitigate dust emissions.

 

Dust

Figure 28: TOTAL PARTICULATE AIR EMISSIONSTotal particulate air emissions

Note: (BREF, BAT, 2001, p.iv) includes dust emissions from 3 lime kilns, 4 recovery boilers and 3 power boilers.

Figure 28 above shows dust emitted in tonnes and total suspended particles per dry weight tonne (TSP/DWT).

This data is collected every three months by a third party and represents a snap shot of dust emissions. It is not derived from continuous monitoring.

Although they exceed BAT, these levels are within Indonesian national limits. The Indonesian limits for power and recovery boilers and for lime kilns are 230 mg/Nm3 and 350 mg/Nm3 respectively.

In 2012, total dust emissions and TSP/DWT decreased.

A modern electrostatic precipitator system was installed during the construction of Recovery Boiler Number 5. We are currently working on several initiatives that will allow further reductions of dust emissions.

Sulphur Oxides - Within BAT

Figure 29: SOX TREATED AIR EMISSIONSSOX Treated Air Emissions

Note: Recalculation of historical ratios based on total mill output have varied ratios reported above for 2008 and 2009.

SOx reported as Sulphur: See note: (BREF, BAT, 2001, p.iv ) includes emissions from 3 lime kilns, 4 recovery boilers and 3 power boilers.

Sulphur oxide (SOx) emissions (kg/ ADT) are within BAT limits. These have been reduced since the commissioning of Recovery Boiler Number 5 and burning of black liquor for fuel. This process has decreased our consumption of higher sulphur fuels such as coal and marine fuel oil. When we burn coal, it is mixed with limestone to precipitate out sulphur as calcium sulphate. This prevents sulphur being emitted as a gas.

Nitrogen Oxides

Figure 30: NOX TREATED AIR EMISSIONSNOX Treated Air Emissions

Note: Recalculation of historical ratios based on total mill output and re-analysis of data have resulted in increased ratios for 2008-10. Increased NOx emissions have resulted from greater amounts of energy being derived from biomass.

Malodorous Gas - Below BAT Lower Level

Figure 31: TRS TREATED AIR EMISSIONSTRS Treated Air Emissions

Note: Recalculation of historical ratios based on total mill output and re-analysis of data have resulted in increased ratios for 2010. TRS reported as Sulphur (mill data H2S). Includes emissions from FL1, 3 lime kilns and 4 recovery boilers. Figure 31 above shows that total reduced sulphur (malodorous gas) levels are well below BAT recommended range.

Emissions to Water

Figure 32: WATER DISCHARGE - TOTAL SUSPENDED SOLIDS (TSS)Water Discharge Total Suspended Solids

Total suspended solid discharge per ADT of pulp has increased as production has increased, but remains just outside the upper limit of BAT range.

Volume of total suspended solids discharged per ADT was slightly lower in 2012, due to operating efficiencies. As can be seen, TSS volumes remain well within our Indonesian permit level.

Figure 33: WATER DISCHARGE - CHEMICAL OXYGEN DEMAND (COD)Water Discharge Chemical Oxygen Demand COD

Note: Treated wastewater, bleached Kraft mills (BREF, BAT, 2001, p.iii). Chemical oxygen demand is below the lower end of BAT range, comparing favourably with European mills. COD decreased lightly lower in 2012 and is well within our Indonesian permitted level.

Figure 34: WATER DISCHARGE - BIOLOGICAL OXYGEN DEMAND (BOD)Water Discharge Biological Oxygen Demand BOD

Note: Recalculation of historical ratios based on total mill output and re-analysis of data have resulted in increased ratios for 2010. Treated waste water bleached Kraft mills. (BREF, BAT, 2001, p.iii)

Biological oxygen demand of wastewater has remained at the lower end of the BAT recommended range since 2008. BOD of wastewater (tons/tonnes) increased to 1,995 tones in 2012 but remains well within Indonesian permitted levels.

Figure 35: WATER DISCHARGE - ADSORBABLE ORGANIC HALIDES (AOX)Water Discharge Adsorbable Organic Halides AOX

Note: Adsorbable organic halide levels per ADT remained at the lower end of the BAT recommended range in 2011 and 2012.

Figure 36: WATER DISCHARGE - TOTAL NITROGENWater Discharge Total Nitrogen

Note: Treated wastewater, bleached Kraft mills (BREF, BAT, 2001, p.iii).

Figure 37: WATER DISCHARGE - TOTAL PHOSPHOROUSWater Discharge Total Phosphorous