The economics of Recycled Paper Sludge conversion into ethanol was here assessed with emphasis on integrating a cellulase recycling system.

Without cellulases recycling this process presented positive economic outputs (payback period of 7.85 years; 10.90 Million US$ of accumulated NPV) despite the modest ethanol titers. Recycling both free and solid-bound enzymes allowed considerable savings of enzyme but also an increase on annual costs (0.88%), resulting on a superior economic output: payback period decreased to 7.25 years; accumulated NPV increased to 14.44 Million US$. Recycling exclusively the liquid fraction enabled a clear costs reduction, however, also total ethanol decreased, attenuating the abovementioned benefits. Targeting higher ethanol concentrations, superior solids consistencies were also evaluated. Despite a costs reduction, total ethanol decreased due to a higher ethanol retention on the solid. A sensitivity analysis further revealed that the cost of enzymes and ultrafiltration membrane may be critical on enzyme recycling economic feasibility.

此处对再生纸污泥转化为乙醇的经济性进行了评估，重点是整合纤维素酶回收系统。

尽管没有使用纤维素酶，但尽管乙醇滴度适中，但该过程仍可带来积极的经济产出（7.85年的投资回收期； 1090万美元的累计NPV）。回收游离酶和固相结合的酶都可以节省大量酶，但每年的成本却增加了0.88％，从而带来了出色的经济产出：投资回收期缩短至7.25年。累计净现值增加至1,444万美元。专门回收液体馏分可以明显降低成本，但是总乙醇量也减少了，从而削弱了上述优势。针对更高的乙醇浓度，还评估了优异的固体稠度。尽管降低了成本，但由于较高的固体乙醇保留率，总乙醇减少了。