from recycled furnish. Retention and strength experiments were conducted with recycled fibre containing non-ionic surface size starch and using a dynamic drainage analyser. Residual starch in the filtrate, filtrate turbidity, first pass retention, drainage time, dry content and short span compression test (SCT) strength were all monitored. The strength effect (SCT, CMT and burst strength) was verified by a hand sheet study where back water was reused. The results show that a combination of coagulant, micro-particle and a new, high molecular weight polymer improved both starch retention and drainage. Simultaneously, significant strength improvement was also achieved. Laboratory studies showed that amylase enzyme inhibitor is efficient in preventing starch degradation. This has been confirmed in several full- scale mill trials. The results were very encouraging, indicating big savings for mills using recycled fibre raw materials. Taken together, the Kemira KemRevive concept presented in this paper can offer value for paper maker in several possible ways: • Increased production • Less new starch needed • Higher strength values/same strength with less raw materials • More efficient and sustainable raw material use • Lowe COD in waste water Until now, most board producers utilising RCF find that a large proportion of the starch is degraded and therefore remains unutilised. This new innovation for starch reuse can create new possibilities that have never before realised on board machines. WORLD PULP&PAPER 67 …amylase enzyme inhibitor is efficient in preventing starch degradation. This has been confirmed in several full- scale mill trials. Figure 6. Effect of FennoSil 55D on strength properties in a handsheet test. Key. CMT = concora medium test SCT = short span compression test AMF = amphoteric polymer CPAM = Cationic polyacrylamide (Dosages, kg/t) 0,0 0,0 0,0 5,4 21,2 9,7 10,4 17,9 7,3 6,9 1,2 6,0 25 20 15 10 9 0 % Hand sheet strenght increase at 17 % ash level Pulp:100 % OCC CPAM (0,12) AMF (0,5) CPAM (0,12) betonite(2) AMF (0,5) CPAM (0,12) AMF (0,5) SCT index increase, % Burst index increase, % CMT30 index increase, % inhibitor product was dosed into the couch pit and into the RCF dilution water. The same property strengths of the final product were maintained while the following savings were observed: • Refining energy consumption was reduced 15-20 kWh/t • Less cationic starch was used, 0.5 kg/t • Effluent COD was 5% lower Mill trial 2. The mill was producing board mainly from recycled fibre. With some grades they had to use extremely high amounts of starch, more than 100 kg/ ton, to achieve strength targets. The mill wanted to reduce starch consumption and improve efficiency. Amylase enzyme inhibitor product was dosed into the RCF tower. In this case the existing retention system consisting of cationic polymer and silica was efficient for the retention of recycled starch. During the trial, the consumption of fresh starch could be reduced significantly from between 4 – 25 kg/ton, depending on the grade.   Mill trial 3. The mill was producing liner and fluting from recycled fibre. They had been suffering from low process pH, high calcium concentration and problems at the anaerobic effluent treatment plant. Amylase enzyme inhibitor product was dosed after RCF pulper and the second dosing point was just before the short fibre tower. Several improvements in the process were observed during the trial. • On average, 7 kg/ton less starch was used. • Process pH was more stable and the amount of added sodium hydroxide could be reduced. • Effluent tower Ca2+-concentration was at lower level. Mill trial 4. The mill was producing liner from recycled fibre and kraft pulp. RCF pulp was treated with amylase enzyme inhibitor and both pulps with the novel amphoteric polymer. During the treatment, starch degradation was reduced in RCF plant and there was more starch coming with RCF pulp to the machine. Also pH was more stable in the RCF pulp. More importantly, during the trial, the production rate was 5% higher than during the reference period. CONCLUSIONS It has been demonstrated that utilisation of a novel retention and strength program, coupled with chemistry that inhibits amylase, can greatly improve key performance and quality standards of paper produced