KEYWORDS: Industrial wastewater, re-use, pulp & paper, filtration, softening

Transcription

1 Industrial Waste waters Re-use: Application of 3FM High Speed Filtration and High Rate Softening as Pre-treatment of Wastewaters from the High Water Consuming Pulp&Paper Sector Marie-Pierre Denieul, 1* Stéphanie Mauchauffée, 1 Eric Barbier, 1 Gilles Le Calvez, 1 Aurore De Laval, 1 Marielle Coste 1 1 Veolia Environnement Recherche & Innovation (VERI), Centre de Recherche de Maisons- Laffitte, Chemin de La Digue BP76, Maisons-Laffitte Cedex, France * marie-pierre.denieul@veolia.com ABSTRACT Industrial waste waters re-use through the treatment of their wastewater to produce water qualities according to industrials own specifications can reduce significantly this impact. The European project AquaFit4Use aims at identifying the best new water technologies to reduce environmental impacts by advanced closure of the water cycle and produce water with the required quality ( fit-for-use ) for re-use in four industrial sectors (pulp & paper, chemistry, food and textile). New technologies are tested to increase recycling, remove particles, separate salts, minimize waste production in order to propose optimized treatment lines. The new high speed filtration 3FM technology and Multiflo TM Softening were tested as pre-treatment of a membrane process in order to fine-tune the quality of the effluent produced by biological treatment with inlet specifications of a nanofiltration process. Case study of an industrial paper mill, which produces paper and board for containerboard and packaging from 100 % recycling fibbers, is reported. KEYWORDS: Industrial wastewater, re-use, pulp & paper, filtration, softening INTRODUCTION Nowadays, industry has a significant impact on available water sources by consuming several billions m 3 of water a year. The problem of water scarcity and the need for a rational water management has thus raised the interest in the use of alternative water sources. However, if water loop closure is aimed for, technologies enabling the exploitation of alternative water sources must be available which meet the quantitative and qualitative water demands of various consumers. In this view, the European AquaFit4Use project aims at identifying the most suitable new water treatment technologies (or combination of technologies) leading to the best solutions to produce water with the required quality ( fit-for-use ) for re-use in four industrial sectors (Pulp & Paper, Textile, Food and Chemistry) which are big water consumers. New technologies are tested to increase recycling, remove particles, separate salts, minimize the waste production in order to propose optimized treatment lines (efficient, reliable and cost effective). The project includes water treatment in its totality (characterization of water qualities required for each sector, development of on line tools for the control of water quality, tests of technologies in possible treatment trains at lab-scale and validation of the most interesting technologies at pilot scale on site) to propose new treatment

2 lines to reach the water quality target for water re-use and which are tailored to suit product demands and standards. In the Pulp & Paper industry, a lot of effort is used to water saving and closing water circuits, also reducing substantially the environmental impact, also by process modeling and automation and Kidney technologies as internal process water treatment. However, a number of problems around the removal of substances are not solved yet and further closing the water cycle causes other problems. Challenges for water re-use in the P&P industry are the following (Negro et al. 1995): - The elimination of residual (soluble) COD and BOD, which can affect both the production process as well as the paper quality; - The removal of stickies and suspended solids, which can induce plugging of pipes and showers, deposit formation, abrasion, loss of tensile strength - The treatment of concentrate streams containing calcium, sulphate, chloride, organics which can lead to salt accumulation in case of water loop closure, corrosion, scaling of pipes and showers in the paper production process. The removal of CaCO 3 is crucial in the last case. This paper focuses on two technologies which were evaluated on paper mill waste waters within the AquaFit4Use project to remove of TSS and stickies on one hand and remove CaCO 3. DESCRIPTION OF TECHNOLOGIES High speed filtration technology as an alternative tertiary filtration to remove particles Tertiary treatment of secondary treated wastewater is the easiest way to improve first step in the direct reuse of water. The filtration of water and wastewater plays indeed an important role within industrial water treatment lines and the removal of particles and stickies can be a major problem to implement a membrane process after a biological treatment, when speaking of recycling water. The purpose of water filtration is to remove particles and colloids which either disturb the industrial process, deteriorate the quality of the final product or support bacteria and viruses that are a danger for human health. The conventional treatment generally consists of coagulation, flocculation, sedimentation and sand filtration. One of the main disadvantages of this process combining sedimentation and sand filtration is the rather long residence time, mostly due to the flocculation and sedimentation phases. Sand filters are as well used but though a good removal efficiency of particle including colloids, they need relatively low filtration velocities thus requiring a large installation area. Although applied at full scale for pre-treatment before a following nano-filtration or reverse osmosis step, the performances of these pre-treatments is not as effective as that of MF and UF (Vedavyasan 2007). Another disadvantage of the conventional pre-treatments is their relatively low filtration velocity (maximum velocity of 20 m/h). A high rate fibre filter was then developed by Veolia Water STI and its high efficacy for the tertiary treatment of waste waters was proved in terms of high filtration velocity and good removal of particulate matter (Ben Aim et al. 2004). The 3FM system (Flexible Fibre Filter Module) is a new high speed filtration device that can be substituted for conventional solid-liquid separation process such as coagulation, settling and sand filtration (Jeanmaire et al. 2007; Lee et

3 al. 2008). Compared with existing rapid sand filters, the 3FM filtration system has a velocity more than 10 times faster at 120 m/hr and has a smaller footprint. Suspended solids are filtrated by flexible fibres in polyamide in a module, which have softness, elasticity and a degree of surface roughness (Figure 1). The filter is packed with bundles of fibres along the module length and influent flow is introduced to the bottom of 3FM. Utilising all of the filter area through deep bed filtration suspended solids particles are captured. The optimum operating parameters are managed according to the influent characteristics desired quality of the treated water. FILTRATED WATER ❷ SERVICE WATER ❶ REJECT (SLUDGE) ❹ ❸ AIR (FOR BACKWASH) 3FM fibers Figure 1. 3FM technology and its principle Principle of 3FM filtration system: Alternation of filtration periods and backwash o Filtration process (❶+❷): Service water is fed through the inlet pipe of the lower part of the apparatus and introduced uniformly into fibrous filter layer. During the filtration process, SS are removed by the fibers and clean effluent water is discharged to upper part. o Backwash process (❶+❸+❹): When inner pressure reaches predetermined value of pressure switch due to SS clogged in the filtering process or time reaches predetermined value on the timer, the backwash process is initiated. SS clogged in the filter are remove in a short time by introduction of air which shake the fibers. Although an innovative process, 3FM operation is easy as a sand filter. Head-loss increases during the filtration cycle and the filtration capacity is recovered by periodic backwashing with a small amount of influent waste water and scouring air (Figure 1). Main impact of 3FM is on TSS content in the water and thus on turbidity as well. This technology is currently used at industrial scale on several WWTP in Korea for obtaining treated water of high quality (Ben Aim et al. 2004) and has been applied as well as pre-treatment to minimize the organic fouling of SWRO membranes used for desalination (Lee et al. 2009; Lee et al. 2010). Removal of scaling compounds with advanced precipitation processes In industry, especially in the Pulp and Paper, the removal of scaling compound, especially calcium carbonate, is a key point in the perspective of a re-use of the wastewater: the recycling of water can indeed induce salt accumulation and thus scaling issues. Generally, the physicochemical treatment of wastewater from industrial operations (softening, acid waste neutralization ) typically involves chemical precipitation of the contaminants via acid-base neutralization (or other means) followed by separation of the solids from the solution. The precipitation reaction, core of the chemical engineering in such processes, is generally a very unstable mechanism when poor homogenization and dispersion of the reagents are applied in the reactor. The consequences are: - Lower removal efficiency (hydraulic short-cut, long induction time);

4 - Over-consumption of reagents (poor dispersion around the reagent input); - Scaling on walls and pipes / residual TSS in treated water (post precipitation); - Low density sludge presenting a high moisture rate (nucleation >>> growth). Moreover, the size, shape, and density of the precipitated particles can have a significant impact on sludge rheology, settling rate and dewatering performance. In turn, these properties can affect the efficacy of solid recovery and/or recycle of these by-products. According to crystallization theory, precipitation is defined as reactive crystallization. This definition is preferred as it emphasizes the formation of the solid product via a chemical reaction. The correlation of the precipitation processing conditions to product properties is determined via the study and control of the following aspects of the process (Figure 2): - Solid-liquid equilibrium; - Crystallization kinetics, i.e. super saturation, nucleation and growth; - Colloid surface chemistry, i.e. the aggregation of particles and the adsorption of impurities; - Reactor selection and design (Demopoulos 2009). Figure 2. A new paradigm for aqueous precipitation research (G.P. Demopoulos, 2009) Most precipitation processes are positively impacted (size of particles, reduced post precipitation, increase of precipitation kinetics, etc.) by increasing solid content (sludge recirculation). Indeed, in a conventional neutralization plant, scaling due to saturated or metastable levels of constituents in the treated effluent can be problematic. Calcium carbonate scaling is commonly observed. Processes that include solids recirculation back to the point of neutralization can reduce or totally eliminate scaling because the increased surface area fosters secondary nucleation and reduces the level of calcium carbonate (and other constituent) supersaturation. Homogeneous solid suspension is then critical criteria to design the process (Spanos 1998; Nason 2008). To solve such problems, advanced precipitation and crystallization processes were developed that address the science of particle formation and growth to improve the recovered solids properties. Veolia has developed and used advanced precipitation processes (Cook 2003; Prokop 2006) with sludge recirculation (Barbier et al. 2009) including forced-circulation, draft-tube crystallizers with custom mixers that yield very high circulation to minimize supersaturated zones. Internal design of the Turbomix reactor improves solid particle homogenisation which allows operating at higher mineral load and reaches high solid/liquid ratio in the reactor. Veolia Water Solutions & Technologies developed new high rate softening processes: Actiflo TM Softening and Multiflo TM Softening (Figure 3) (i.e. Chemical precipitation of hardness, alkalinity,

5 silica and other constituents (e.g., heavy metals) for water production and wastewater reuse by the addition of lime, carbonate ion, metallic salts, polymer and recycled sludge. Turbomix reactor Figure 3. High rate precipitation process Multiflo TM with Turbomix reactor METHODOLOGY Case study and global strategy These two new technologies were tested on real industrial waste waters from one paper mill which produces paper and board for containerboard and packaging from 100 % recycling fibbers. They were tested as part of a global treatment line in view of adding a tertiary treatment composed of one or more technologies to the existing on site treatment plant which is the following: Anaerobic Aerobic Sedimentation Reject to the river. In order to re-use water, it is important to focus on new technologies which fit with the described objectives and to compare them to existing standard processes. Water characterization is a key point to fine tune the process to the final water quality request. In order to define new one step and hybrid processes, the following key steps of the global treatment train has been considered (Figure 4): - Biological treatment (anaerobic and MBR processes) to reduce residual (soluble) COD and BOD; - Filtration processes (3FM high speed technologies and nanofiltration); - Tertiary treatments to reduce hard COD (AOP s, coagulation/precipitation); - Integration of processes in the treatment line to minimize the waste production and separate salts (evapoconcentration and electrodialysis) in order to prevent salt accumulation and scaling.

6 Low water quality to be reused MBR AOP Paper mill wastewater Anaerobic Process Aerobic Process NF 3FM Multiflo Softening Retentate High water quality to be reused Water to be re-used or Evaluation of technologies: - AOP technologies - Evapo-concentration Waste minimization (or recycling ) Figure 4. Global treatment line Direct treatment of wastewater finished always by a nanofiltration step as a polishing step. Key point is in a necessary pre-treatment of nanofiltration step in terms of conversion rate, flux and reagents consumption. In this view, 3FM filtration was tested as pre-treatment for nanofiltration and Multiflo TM softening as pre-treatment of nanofiltration after 3FM treatment to avoid scaling of membrane during NF treatment (Figure 5). Technologies were first evaluated at lab-scale results and are currently tested at pilot scale on the industrial paper mill in the following treatment train: AOP (O 3 ) Water to be re-used? Paper mill Anaerobic Aerobic 3FM AOP (O 3 ) Can be recycled into Anaerobic??? Existing on site WWTP Evapo Water to be re-used? Multiflo softening NF Final waste Figure 5. Pilot tests carried out on industrial paper mill Water to be re-used? The final objective is to produce water with a fit-for-use quality based on water quality criteria defined by the industrial for re-use purposes based on where in the production process the produced water should be substituted to fresh water (Table 1).

7 Table 1. Water quality criteria for re-use purpose on the case study paper mill Quality of reclamation water LOW quality (misc. dilution) MEDIUM quality (spraying nozzle) HIGH quality (white paper grade) Conductivity 500 µs/cm 500 µs/cm 500 µs/cm Cl < 300 mg/l < 200 mg/l < 200 mg/l Ca < 200 mg/l < 60 mg/l < 60 mg/l Colour Doesn t matter Doesn t matter None Solids Coarse particle mg/l filtration Particles < 5 µm 10 mg/l COD Doesn t matter < 200 mg O 2 /l* < 50 mg O 2 /l BOD Reduced low < 3 mg/l *: not so important Bench scale units and pilot plants Filtration feasibility tests were carried out on a 3FM bench scale unit (Figure 6) on waste waters sampled after clarification of anaerobic/aerobic processes from the paper mill. 100 litre of effluent were filtrated at a flow of 65 l/h. TSS, turbidity and COD were followed in time. Softening lab-scale tests were done on a continuous bench scale unit of advanced crystallization (Figure 6): 5 litre Turbomix reactor + lamellar settler (10 l/h flow rate, Ts = 30 min, Sludge recirculation ratio: 10:1). The purpose of these tests was to remove scaling compound before the NF membrane treatment in order to re-use the wastewater. SERVICE WATER 3FM module FILTRATED WATER RECIRCULATION PUMP PRECIPITATION TANK SETTLER FEED PUMP TREATED EFFLUENT SLUDGE Figure 6. Lab scale 3FM unit and Multiflo TM Turbo softening bench-scale unit Pilot scale tests are currently ongoing on site with a 3FM industrial module unit (Ø200), which is the smallest industrial unit and a Multiflo TM Softening pilot plant which characteristics are described below (Figures 7 and 8): - The 3FM pilot is a fully automated industrial module pilot. It has been implemented at the outlet of the industrial WWTP settler. As some paper particles were sometimes present in the outlet of the settler a 1 mm pre-filter was implemented upstream the 3FM to remove big particles. Filtration is done at flow rate of 2 m 3 /h and periodic backwashes were initially programmed every 4 hrs. TSS level, turbidity, total and soluble COD were continuously monitored to evaluate the impact of 3FM filtration on TSS and turbidity depending of the evolution in time of waste waters from the WWTP.

8 - The Multiflo TM softening pilot has an 18 L Turbomix reactor and treats the 3FM filtrate at a flow rate of 125 L/h with a total residence time of 30 min (Remark: the 3FM filtrate is stored in an intermediate tank with a 2 m 3 capacity). Starting conditions were determined with lab scale experiments (injection of lime to a ph = 9.5, sludge recirculation ration 5:1, 40 ppm FeCl 3 as coagulant and 0.4 ppm polymer as flocculent) and were then adapted considering first results of the pilot trials, the objective being to reach the best softened water: total completion of CaCO 3 precipitation, lowest Ca concentration and a turbidity of 2 NTU. Flow in min. (l/h) 1500 Flow in max. (l/h) 5000 Flow out max (l/h) 5500 Limiting parameter High concentration of TSS Chemical reagent None Waste produced Water coming from backwash with SS concentration Industrial module Figure 7. Industrial 3FM pilot unit (Ø200 3FM module) Reaction tanks Lime input to ph target Coagulant Flocculant Feed Treated water Lamellar settler Flow in min. (l/h) 100 Flow out max (l/h) Chemical reagent Ca(OH) 2, FeCl 3, Polymer (AN934) Waste produced CaCO 3 Sludgerecirculation X : 1 Sludge extraction Figure 8. Multiflo TM Turbo softening pilot plant and process description RESULTS AND DISCUSSION Preliminary results obtained at lab scale Lab scale trials allowed comparing 3FM/NF and 3FM/Multiflo-softening/NF versus direct NF. Very good results were obtained with 3FM regarding TSS content abatement with 91% and as well for turbidity with 93% (Table 2). 3FM filtration has no impact on dissolved COD removal but only particular COD is removed. Though the bench scale unit has no backwash system and is not representative of the hydrodynamic of an industrial unit good results were obtained at lab

9 scale: 3FM showed at lab scale to be a promising technology for a pre-filtration stage before NF filtration to remove TSS and thus limiting membrane scaling. Table 2. Results of 3FM filtration applied to Pulp & Paper industrial waste waters Before 3FM After 3FM ph Conductivity (ms/cm) TSS (mg/l) 23 2 Turbidity (NTU) tcod (mg O 2 /L) Granulometry analysis showed a cut size of about 5 µm, which does correspond to 3FM industrial specifications (indicated cut size for industrial module ca. 10 µm) Feed 15' filtration 30' filtration 60' filtration 90' filtration ,01 0, d µm (log scale) Figure 9. Particle size distribution of 3FM filtrate Consecutively, softening was carried out at ph = 9 on 3FM filtrate with a joint injection of CaCl 2 (10 g/l) and Ca(OH) 2 (5 g/l). First reagent was used to remove alkalinity; it reacts with carbonate to form calcium carbonate. Second reagent was used to maintain ph equal to 9. Main impact of softening is thus on alkalinity and calcium concentration as shown in Table 3. Very good results were obtained regarding Ca and alkalinity abatement with 67 and 60% respectively. Table 3. Results of softening on 3FM filtrate Before softening After softening ph Ca (mg/l) Alkalinity (mg CaCO 3 /L) Na (mg/l) Lab-scale tests subsequently done on NF filtration with this treated water allowed to reach a conversion rate of 93% instead of 80% without pre-softening with a higher permeability, a better quality of permeate and no use of acid which have positive effect for re-use (Table 4). (Remark: These tests were done by the AquaFit4Use partner Envirochemie GmbH).

10 Table 4. Comparison of analysis results of differently pre-treated and filtrated effluent Parameter Unit Effluent Effluent softened ph Antiscalant + Antiscalant 80% recovery l/(m 2.h.bar) Max. recovery rate RPP % max. 90 # 93 Perm. RPP % Conductivity µs/cm * 160 Calcium mg/l 2-14 < 1 Sodium mg/l 30-70* 28 Chloride mg/l 50-80* (400) 32 Sulphate mg/l < 5* < 5 DOC mg/l 1-2* 2 COD mg O 2 /L < 15* (24) < 5 # visible scaling detected * results of tests runs on semi-technical scale at 80% recovery It was then decided to implement a Multiflo softening unit before the NF unit at pilot scale since better results were obtained after softening on the NF unit and less scaling was induced by the softened effluent. For both technologies, these encouraging results had then to be validated on site at pilot scale on the industrial paper mill to see the impact of variations of load of the real waste water in time. On site pilot case study - Impact of load variations of the WWTP effluent Pilot scale trials started mid April 2011 on the industrial paper mill. The 3FM pilot (2 m 3 /hr) has been implemented at the outlet of the industrial WWTP settler and its effluent was then treated in line by the Multiflo TM Softening pilot at a flow rate of 125 L/h. Compared to the results obtained at lab scale on a spot sample, the TSS removal was lower with an average value of 52% (see Table 5 and Figure 10), whatever the concentration in the feed was, while the turbidity removal was of 48% in average (see Table 5 and Figure 11). No impact is observed on soluble COD: 3FM filtration has only an impact on particular COD as can be observed on the impact on total COD values. Table 5. Results of 3FM filtration at pilot scale Before 3FM After 3FM Average removal ph Conductivity (ms/cm) TSS (mg/l) 2-57 (max. 106) 2-16 (max. 36) 52% Turbidity (NTU) 6-36 (max. 111) 3-20 (max. 64) 48% tcod (mg O 2 /L) % These lower results compared to the ones obtained at lab scale can be explained by the high clogging power of the WWTP effluent due to a pretty high calcium content. Though initially programmed every 4 hrs, backwashes had then to be implemented on the basis of a pressure threshold of 0.8 bars upstream the fibre module to fully recover the filtration capacity of the filter. Backwashes took then place every 2-3 hrs, which do correspond to the industrial

11 specifications of the 3FM (filer run time: ~2-3 hrs between backwashes, but may vary according to flux). The reject water volume used for backwashes is in between 2-4% of the maximum treated volume (4-6 m 3 during the filtration cycle), which is slightly higher to the industrial specifications (1% of the maximum treated volume), due to the clogging potential of the influent to be treated. 70 TSS (mg/l) Problem of aeration in the Aerobic process TSS feed TSS 3FM filtrate /04/ /04/ /05/ /05/ /05/ /05/ /06/2011 Date 09/06/2011 Figure 10. Impact of 3FM filtration on TSS 16/06/ /06/ /06/ ,0 Turbidity (NTU) 100,0 80,0 60,0 40,0 Feed 3FM filtrate 20,0 0,0 21/04/ /04/ /05/ /05/ /05/ /05/ /06/2011 Date 09/06/2011 Figure 11. Impact of 3FM filtration on turbidity 16/06/ /06/ /06/2011 As expected very good results were obtained with the Multiflo TM -softening process. Ca removal was of 95-98% during the whole trial period reported (Figure 12) whatever the process conditions were. Alkalinity removal was first of only 65-75% with the initial process conditions (sludge recirculation ratio 5:1, ph = 9.5), while final turbidity was of 5-20 NTU.

12 Ca 2+ concentration (mg/l) Sludge recirculation 5 : 1 ph = 9.5 Sludge recirculation 10 : 1 ph = 10.5 Ca inflow (3FM filtrate) Ca supernatant 0 21/04/11 28/04/11 05/05/11 12/05/11 19/05/11 26/05/11 Date 02/06/11 09/06/11 16/06/11 Figure 12. Impact of Multiflo TM Softening on calcium 23/06/11 30/06/11 Total alkalinity (mg CaCO 3 eq/l) Sludge recirculation 5 : 1 Sludge recirculation 10 : 1 ph = 9.5 ph = 10.5 Total alkalinity feed Total alkalinity supernatant 0 21/04/11 28/04/11 05/05/11 12/05/11 19/05/11 26/05/11 Date 02/06/11 09/06/11 16/06/11 23/06/11 Figure 13. Impact of Multiflo TM Softening on total alkalinity However, it is known that the increase of the solid rate by a higher sludge recirculation ratio improves the global process efficiency (Barbier 2009). In addition, at a higher ph value of 10.5 the hydrogen carbonate carbonate equilibrium is shifted towards the carbonate form, then total completion of alkalinity removal is favoured. Process conditions were then changed after 1.5 months of trials (Table6). 30/06/11

13 Table 6. Results of softening of 3FM filtrate focused on optimum conditions (ph = sludge recirculation 10:1) Before softening (3FM filtrate) After softening Average removal ph Ca (mg/l) % Alkalinity (mg CaCO 3 /L) % Turbidity Total COD % Soluble COD A higher alkalinity removal of 85-95% was then obtained with a higher sludge ratio of 10:1 at ph 10.5 (Figure 13), while turbidity was as well improved down to NTU (Figure 14). One has to keep in mind that the initial turbidity do correspond to the one of the 3FM filtrate while the residual turbidity after softening correspond to the abatement of the initial turbidity together with the abatement of the suspended solids formed in the reactor (2 g/l) during the softening process. The final turbidity is thus the residual of the global removal. (Remark: it was observed on the pilot, that the turbidity was higher during day time especially when the effluent temperature was high due to convection). Turbidity (NTU) Sludge recirculation 5 : 1 Sludge recirculation 10 : 1 ph = 9.5 ph = 10.5 Turbidity inflow (3FM filtrate) Turbidity supernatant /04/11 28/04/11 05/05/11 12/05/11 19/05/11 26/05/11 Date 02/06/11 09/06/11 16/06/11 Figure 14. Impact of Multiflo TM Softening on turbidity 23/06/11 30/06/11 It is remarkable as well to observe that malfunction in the biological process of the industrial WWTP has had no impact on the softening process. On May 27 th a malfunction in the aeration of the aerobic process was reported by the industrial which led to a higher COD value and TSS value of the 3FM filtrate at the inlet of the softening. However, no impact was observed on the calcium removal while alkalinity was slightly higher than usually in the softened effluent. A slight removal of 15-25% of total COD was in general observed which is normal as the Multiflo process was initially developed to remove particulate matter (Figure 15). A low removal of soluble COD is as well observed probably due to adsorption on the formed flocs in during the softening process.

14 Total COD - Soluble COD (mg O 2 /L) /04/11 Sludge recirculation 5 : 1 28/04/11 05/05/11 12/05/11 19/05/11 26/05/11 Date Sludge recirculation 10 : 1 ph = 9.5 ph = /06/11 09/06/11 Total COD feed (3FM filtrate) Total COD supernatant Soluble COD feed Soluble COD supernatant 16/06/11 23/06/11 30/06/11 Figure 15. Evolution of total and soluble COD in the softening process Evaluation at pilot scale of the impact of softening on the following NF process is still under evaluation. Results will be presented during the conference. CONCLUSION The Aquafit4Use project aims to develop innovative treatment trains to close the water loop in industrial sectors which are high water consumers. In the Pulp&Paper sector one of the major concerns is to remove suspended solids and calcium content when closing the water loop in order to prevent scaling of pipes, showers; these phenomena can be as well a major problem to implement a membrane process after a biological treatment process, when speaking of recycling water. In this view the new high speed filtration 3FM technology and Multiflo TM -softening technologies both developed by Veolia Water Solutions & Technologies were tested on wastewaters from an industrial paper mill producing paper and board for containerboard and packaging from 100% recycling fibbers. Requirements given by the industrial sector for the reuse of water allowed showing at lab scale that the combined 3FM and Multiflo TM -softening processes allowed to fine-tune the quality of the treated effluent with the inlet specifications of a consecutive nano-filtration step: higher recovery was obtained together with a better permeate quality. This treatment train was then tested at pilot scale at the outlet of the industrial WTTP of the paper mill to evaluate the impact of the variations of the wastewater on the treatment process. TSS removal of the 3FM technology was of 50%. Multi-softening process gave very results for the removal of Ca and total alkalinity with 95-98% and 75-85% removal respectively. Final turbidity of the softened effluent was around 2-10 NTU. Evaluation at pilot scale of the impact of softening on the following NF process is still under evaluation

15 ACKNOWLEDGMENTS This research was performed in the implementation of the European project «AQUAFIT4USE» (Grant Agreement n ), funded under the European Commission s Seventh Framework Program (FP7). REFERENCES Ben Aim, R.; Han, K.B.; Woo, H.J.; Marteil, P.; Im, J.H.; Kim, C.W.; Hwanf, M.H. (2004). An innovative deep bed filter for the tertiary treatment of wastewater. World Filtration Congress, New Orleans, USA. Barbier, E.; Briand, A.; Robert, J.; Logette, S.; Coste, M., Beaudet, J.-F. and Banerjee, K. (2009). Impact of reactor design on the high rate softening process. 8th World Congress of Chemical Engineering, Montreal, August Cook, R. G. (2003). The Dense Sludge Process, An Advanced Physicochemical Process for the Cost-Effective Treatment of Metals-Bearing Acidic and Alkaline Wastewaters. A VWNA technical introduction and overview. Demopoulos, G.P. (2009). Aqueous precipitation and crystallization for the production of particulate solids with desired properties. Hydrometallurgy, 96, Jeanmaire, J.P.; Suty, H.; Marteil, P.; Breant, P.; Pedenaud P. (2007). Application of the 3FM filter to sea water filtration. Wat. Sci. and Tech., 56(10) Lee, J.J.; Cha, J.H.; BenAim, R.; Han, K.B. and Kim, C.W (2008). Fiber filter as an alternative to the process of flocculation-sedimentation for water treatment. Desalination, 231, Lee, J.J.; Johir, M.A.H.; Chinu, K.H.; Shon, H.K.; Vigneswaran, S.; Kandasamy, J.; Kim, C.W.; Shaw, K. (2009). Hybrid filtration method for pre-treatment of seawater reverse osmosis (SWRO). Desalination, 247, Lee, J.J.; Johir, M.A.H.; Chinu, K.H.; Shon, H.K.; Vigneswaran, S.; Kandasamy, J.; Kim, C.W.; Shaw, K. (2010). Novel pre-treatment method for seawater reverse osmosis: Fibre media filtration. Desalination, 250, Negro, C.; Blanco, A.; Gaspar, I.; Tijero, J. (1995). El Agua en la industria papelera, Ingeneria Químíca, 27(317), Prokop, D. (2006). Recycle synthetic fluorspar and fluoride release minimization, Achema Frankfort, Germany, May. Vedavysan, C.V. (2007). Pre-treatment - an overview. Desalination, 203,