When wet waste is dewatered, it leaves behind a dry biosolid. This byproduct is land filled, burned, used as fertilizer or mixed with compost to produce a viable soil amendment. Yet some states restrict biosolid management and in California strict regulations now limit what water and wastewater utilities can do with biosolids.
One company, EnerTech, invented another option: turning biosolids into clean burning renewable fuels. Through its SlurryCarb process, high temperatures and pressure are used to rupture organic biosolid cells and release moisture. The process turns biosolids into a fuel, similar to lignite coal, with much less energy than conventional drying.
The slurry produced is free of organic pollutants and pathogens and has an energy content of 5,000 Btu/lb. With a shorter drying time - requiring as much as two-thirds less energy than conventional drying - SlurryCarb is about 30 percent cheaper than traditional drying.
This fuel, called E-Fuel, was approved by the California Energy Commission and the Green-e Renewable Electricity Certification Program. To produce E-Fuel, EnerTech needed a full-scale facility, so it teamed with HDR to design and build the first SlurryCarb plant in Rialto, Calif.
The project began with great urgency because several counties in California were passing laws restricting biosolid disposal. Some were completely banning land application or burning.
HDR implemented a fast-track schedule and started designing a processing plant, capable of taking in 675 wet tons per day, with temperature and pressure requirements much different than traditional facilities.
The plant will process sludge from five California municipalities and turns out as much as 145 tons of renewable E-Fuel per day. E-Fuel will replace coal used to power a cement plant, reducing ore consumption and emissions while offering a green, renewable fuel source alternative.
当湿废物脱水后，残留下了干生物废料。这些副产品常被用于土地回填，焚烧，用作肥料或混合其他用来做成可利用的土壤修正产品。然而，一些国家限制生物废料管理及利用. 在美国加州现在州政府开始限制给水和废水处理过程中生物废料的管理及利用.
EnerTech发明了另一种选择把生物废料改造成清洁可燃的可再生燃料。该工艺通过其SlurryCarb处理过程中高温和高压使生物废料细胞破裂并释放水分.这一工艺用比传统的干燥过程少得多的能量将生物废物改造成类似褐煤的固体燃料.
该泥浆产品不含有机污染物和病原体但是却拥有5000仟卡/磅能源含量。该工艺用更短的干燥时间,仅用传统干燥所需三分之二的能源, 该工艺比传统烘干节省30%左右的费用.
这种燃料，被成为电子燃料，得到美国加州能源委员会和绿色可再生能源机构的认证。为了生产电子燃料,EnerTech需要一个全面的设施，所以它与HDR公司在美国加利福尼亚州联手设计和建造的第一SlurryCarb工厂.
该项目肩负着极大的紧迫感开始实施，因为加利福尼亚州的几个县市已经在通过法律限制生物废料的处置。有些县市甚至完全禁止土地回填的申请或焚烧。
HDR公司以快速时间计划开始设计一个能够处理675吨湿污泥的处理工厂.该工艺在温度和压力的要求与传统的设施完全不同。
该工厂将处理污泥来自5个加州市政府的市政污水处理厂并可生产高达145吨可再生电子燃料. 该电子燃料将取代煤炭用于力水泥厂，减少铁矿石的消费和排放，同时提供了绿色可再生的替代燃料来源。
