Something quite old is leading to something quite new in the wastewa- ter treatment industry. In systems ranging from Florida to Egypt, solar power is the driving force behind the technology in wastewater treatment plants. Solar drying is a technique that is being used increasingly by operators of medium-sized and large wastewater treatment plants. The process re- duces sludge disposal costs and protects the environment. In all types of climates and a wide range of wastewater plant sizes, solar dryers by HUBER are helping communities save money and support the environment. In Sanford, Florida, a treatment plant with a capacity of 8.5 million gallons per day was recently installed. It is similar in construction to a plant in Egypt that has been officially awarded by Guinness World Records as the largest water treatment plant in the world with a capacity of 5.6 million cubic meters per day. The common theme in both plants, and others, is the sun. The process extracts water from sewage sludge, and while using solar energy to treat wastewater is not a revolutionary idea, doing so on a large scale is a far more recent development. “We had a very basic dewatering system where we were getting about 16 percent solids,’’ said Anne Nelson, the lead plant operator at the Sanford plant. “With the HUBER system we get about 75 percent sol- ids, and it’s very dry. The 16 percent that we got from the other system was not as dry, kind of like a gelatin mold. The solids from the HUBER system are not quite soil, but it’s very dry, it reduces the number of trucks we have to send out and is more easily used.” Solar ‘Sludge Turners’ The Bahr El-Baqar plant is the standard by which all future solar systems will be measured. It holds three Guinness World records, but the process in Egypt, Sanford, and other systems is roughly identical except for plant capacity. The HUBER Sludge Turner SOLSTICE® units work in greenhouses. The turner travels on rails and repeatedly rearranges the sludge on the ground. During the movement, the sludge is dried by solar energy. At the end of the drying lane, the sludge turner picks up the dry granules in the tool that repositions the sludge during its forward movement. The dry material is relocated to a recess in the ground, then collected and transported to a container. Wastewater Plant Develops New SystemWith Power from an Old Source By Thomas Renner
HUBER has developed an innovative wastewater treatment system that uses solar power to reduce sludge disposal costs and protects the environment. Photo: igus
The facility in Sanford includes a 410-foot long drying field, which is 39 feet wide. The greenhouse is slightly larger, to accommodate load - ing, unloading and maintenance areas. The dryer can accept 4,790 wet tons per year. The system takes a solid mixture that is 78 percent moisture and wa- ter and 22 percent dry solids and converts it to 75 percent dry solids. Evaporation reduces the amount of wet tons that need to be hauled offsite to 1,405 tons per year. The system in Egypt includes 128 sludge turners and can accept ap- proximately 475,000 tons of sludge per year. The system is constructed on more than 39 acres and includes 16 greenhouses. The costly infrastructure project – it cost about $700 million in U.S. currency – is critical in the region. The Bahr El-Baqar drain is one of the most polluted in the country. Industrial waste and sewage from Cairo, along with agricultural runoff, pesticides and fertilizers, end up flowing into the drain. Water quality scores range from 37-48, a rating that is marginal or poor. Much of the water is used for irriga - tion and fishing. Reliance on energy chains An important component to the HUBER Sludge Turner SOLSTICE® units are energy chains manufactured by igus. The company, based in Germany, runs its North American operations out of Providence, R.I. The energy chains include the company’s chainflex cables, which pro - vide reliable data transfer and energy supply for the sludge turners. The energy chains in the application in Egypt travel approximately 100 meters, while the Sanford system e-chain is 128 meters or nearly 140 yards, about 1.5 football fields. “Energy chains are the best solution for cable guidance on long trav- els,’’ said André Großer, HUBER SE Product Manager. “It requires little room, protects the cable, and is easy to install and maintain.” The chainflex cables are also critical to the sludge turner. Three indi - vidual cores and a CFPE cable, all with a TPE outer jacket, ensure con-
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DECEMBER 2021 csengineermag.com
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