The Gippsland Water Factory -revolutionising the treatment of pulp and paper mill effluent

摘要

The Gippsland Water Factory (GWF), currently under construction in the Gippsland region of Victoria, Australia, sets a new benchmark in pulp and paper wastewater treatment. The innovative wastewater treatment and recycling system will treat up to 35ML of domestic and industrial wastewater daily and is believed to be the first treatment plant of its type to use membrane bioreactor (MBR) technology for the treatment of paper and pulp mill effluent.rnAround 60% of the capacity of the GWF will treat a combined effluent from Australian Paper's (AP) Maryvale Mill, Australia's largest paper-making complex. The remaining inflows will be domestic wastewater.rnAP's Maryvale Mill operates on a mixed feed of Pine and Eucalypt and the waste discharged to the G WF will be mainly from the bleaching and pulping portion of the process.rnKey to the effective treatment of this mix of wastewater is that AP's industrial effluent and the domestic wastewater collected from surrounding communities will remain in separate treatment streams throughout.rnThe GWF pilot plant (GWF PP), in operation since mid 2005, has demonstrated that the pulp and paper mill effluent can be successfully treated using MBR technology. An important feature of the industrial treatment process stream is pre-treatment using anaerobic bulk fermentation prior to MBR treatment.rnThe GWF PP program revealed potential for severe transient load shock and nutrient limitation stress effects (e.g. slime formation) and helped focus designrneffort on nutrient management and methods of minimising impacts from slime related effects such as settleability. A key advantage of the anaerobic pre-treatment, in addition to improved sludge treatment and energy recovery is that it enables sharing of nutrients from plant sludges from other sections of the treatment plant particularly the nutrient rich waste activated sludge from the domestic waste treatment stream. These nutrients in turn help to ensure adequate biomass nutrition in the nutrient poor pulp mill effluent.rnAnaerobic pre-treatment also offers the potential to significantly reduce passage through the treatment process of strong oxidants such as chlorates. Technical aspects of this expected performance benefit will be presented in the paper.rnThe separate GWF process streams (i.e.domestic and industrial) mean that the domestic wastewater stream is not contaminated by the biologically refractory dissolved organics (often referred to as "colour") and salinity present in the industrial effluent. This feature is of particular value as the treated domestic stream will be desalinated (via reverse osmosis) after MBR treatment and supplied to the Maryvale Mill to supplement the existing process water supply.rnAlso of importance in pulp mill effluent treatment is the treatment of suspended solids and BOD. The GWF PP experience, which will be reported in this paper, indicates that in regard to Total Suspended Solids (TSS) and Biochemical Oxygen Demand (BOD) the full scale GWF will achieve a treated "non detectable " effluent quality of less than 1 mg/L and 5 mg/L respectively.