Biogas-Powered Sludge Dryers: Turn Farm Waste into Energy and Fertilizer|News|STCrushers

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Biogas-Powered Sludge Dryers: Turn Farm Waste into Energy and Fertilizer

Sep 16,2025

Small-scale farmers in Thailand’s Chao Phraya Delta used to have two big problems: too much pig manure sludge (which polluted rivers) and high electricity bills for drying crops. Now, biogas-powered sludge dryers solve both—turning sludge into biogas to run the dryer, then turning the dried sludge into fertilizer. It’s a closed-loop system that cuts waste, saves money, and helps farmers earn extra income. Here’s how it works: Pig manure is fed into a small biogas digester (usually 5-10 cubic meters) on the farm. The digester breaks down the manure to produce biogas, which is stored in a tank. This biogas then fuels the sludge dryer’s burner, heating the drum to dry wet sludge (from the digester) into a crumbly fertilizer. A 100-pig farm in Thailand’s Suphan Buri province installed this system and now produces 8 cubic meters of biogas daily—enough to run the dryer for 8 hours and still have leftover gas for cooking. The financial benefits are huge. Before, the farm paid 80/monthtohavesludgehauledawayand 50/month for electricity to dry corn. Now, they spend 0onsludgedisposal,0 on drying electricity, and sell 100kg of dried fertilizer monthly for $30. “It’s like getting paid to solve our waste problem,” says farmer Somsak Thongdee. These dryers are also easy to maintain. They have simple mechanical parts (no complex electronics) that local mechanics can fix. The biogas system only needs cleaning once every 6 months, and the dryer’s drum liner lasts 2 years—far longer than standard electric dryers. A farmers’ cooperative in Vietnam trained 10 members to maintain their shared dryer, ensuring it runs year-round with minimal downtime. For countries pushing for Low carbon agriculture, these dryers are a win-win. They reduce greenhouse gas emissions (biogas replaces fossil fuels) and water pollution (sludge is turned into fertilizer, not dumped). In the Philippines, the government now offers subsidies for biogas-sludge dryer systems, helping 500 farms adopt the technology in 2023 alone.