Solar Drying System Design for Sludge Produce at NWWTP
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Date
2019-06-22
Authors
Odeh, Aya
Shaablo, Itaf
Sholi, Maysoon
Shabaro, Noor
Dwaikat, Sojoud
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Abstract
In West Bank, there are five major wastewater treatment plants in different governorates. The wastewater treatment processes do not produce treated water only, another stream which contains all the treatment residual -called “sludge”- is resulted as well. Generally, there are few possibilities to manage it such as landfill, incineration or use it as a fertilizer in agriculture with limited amount. However, the sewage sludge contains water mostly which must be reduced by common dewatering processes until a DS (dry solids) concentration to about 90%. Thus, a solar- thermal greenhouse drying system was designed, the dryer consists of a parabolic roof structure covered by polyethylene sheets on a concrete floor and a flat heat exchanger with boiler heats a water at 90 ºC flows inside HDPE (High Density Poly Ethylene) pipes under the concrete floor. Dimension of the dryer (one bed) is 23 m in width, 45 m in length and 2.5 m in height. Six fans were used to ventilate the dryer. The dryer was installed at Nablus Waste Water Treatment Plant (NWWTP). Results obtained showed that four beds were needed to handle the daily dewatered sludge of 15 tons and the drying air temperatures in the dryer varied from 30°C to 65°C. The drying time was within 4 hours a day and good quality dried product was obtained. The estimated of payback period of the dryer is 5 years.