Solar drying of sewage sludge is a technique that is increasingly used also by operators of medium-sized and large wastewater treatment plants to reduce sludge disposal costs and at the same time protect the environment. Previously, primarily smaller sewage treatment plants and particularly plants in Germany and France have used solar sewage sludge dryers. Today, even operators of medium-sized and large wastewater treatment plants from all over the world order solar dryers.
Project Cali, Colombia
For more than a year a HUBER solar dryer has been in operation in a tropical climate zone at Cali, a large city in Colombia. The dryer handles a wastewater flow in excess of 5 m³/s. High solar radiation combined with an additional heating render it possible to process up to 60 m³ press sludge on some days. Four type SRT 9 machines are installed at Cali to dry the sludge directly at source and use it as fertilizer for the production of sugarcane. Previously, the sludge had to be transported to a landfill by trucks, which was quite an expensive solution.
An about 50 m long conveying belt has been installed to transport the sludge from the existing dewatering building to the new greenhouses where the sludge is distributed to individual treatment lines to be processed by the HUBER machines. In this way the fully automated solar drying system could be integrated into the customer’s existing system.