This project concerns a composted sludge belt dryer in South Africa. The sludge came from wastewater treatment plants across Gauteng province. After 6-8 weeks of windrow composting, the material still had 45-50% moisture. Too wet for bagging. Too wet for screening. Too wet for efficient transport. The compost was heavy, sticky, and difficult to handle.
This project concerns a composted sludge belt dryer in South Africa. A waste management company outside Johannesburg, South Africa, was processing municipal sewage sludge into compost. The sludge came from wastewater treatment plants across Gauteng province. After 6-8 weeks of windrow composting, the material still had 45-50% moisture. Too wet for bagging. Too wet for screening. Too wet for efficient transport. The compost was heavy, sticky, and difficult to handle.
The operations manager (let's call him Johan) explained the challenge: "Composted sludge is a great soil amendment. But at 50% moisture, it's a mess to handle. It clogs our screens. It weighs a fortune to transport. Farmers don't want wet, heavy bags. We needed to get moisture down to 15-20% for bagging and sale."
The company processes about 15,000 tons of wet sludge annually, producing about 8,000 tons of compost after drying. They sell to farms, nurseries, and landscaping companies across South Africa.
Johan looked for a drying system that could handle 45-50% moisture input and produce 15-20% output efficiently. He found the DHG series belt dryer from RICHI.
Name:
Sludge Dryer
Country:
South Africa
Date:
2025
Capacity:
2-3 tons/hour
Model:
DHG-100
drying area:
43 m²
Raw Materials:
Municipal sludge, Green waste, Sawdust
Target Moisture Content:
15-20%
From the belt dryer table, the DHG-1000 (electrically heated) was selected. Why this model?
Johan chose the electric model because their facility had no steam boiler. The DHG-1000 belt dryer runs on electricity only – simple installation.
South Africa's major cities produce thousands of tons of sewage sludge annually. Johan's company receives:
The composting process takes 6-8 weeks in windrows. The compost is turned weekly. By the end, the material is stable and pathogen-free. But moisture is still 45-50%.
The dried compost is used for:
The DHG-1000 arrived at the Port of Durban – Africa's largest and busiest port.
Shipping time from Qingdao to Durban is about 25-30 days. The machine was packed in a 40-foot container with:
Customs clearance in Durban took about 7 days. Total landed cost was about 25% higher than the FOB price.
Installation took three weeks. Johan's team prepared a concrete foundation – the DHG-1000 is about 12 meters long. They poured a 200mm reinforced slab.
The electrical hookup required 380V, 50Hz three-phase (South African standard). The 70kW heater required a 150-amp breaker. Ventilation ducting was installed to exhaust moist air.
The first test run was with composted sludge at 48% moisture. The material was spread on the belt (layer thickness 50mm). Belt speed was set to 20 minutes per layer – total drying time 100 minutes across 5 layers. Output moisture: 18%. Perfect for bagging.
After six months of operation, Johan documented the following results:
Before (no mechanical drying – only windrow composting):
After (DHG-1000 belt dryer):
Production output:
Cost savings:
The machine cost delivered approximately R1,400,000 (about €70,000). Payback period was about 4-5 months based on revenue increase alone.
Here's what Johan said after six months (paraphrased from a conversation):
"Wet compost is a nightmare. It sticks to everything. Our screens would clog every hour. The bags were heavy and leaked. Farmers complained about the mess.
The DHG-1000 changed that. The belt dryer takes our compost from 50% moisture down to 15-18%. The product is dry, free-flowing, and easy to handle. We can now bag it efficiently and sell it at a premium.
The 5-layer design is the key. The material passes through five belts, each with hot air. Uniform drying, no hot spots. The gentle movement doesn't break the compost structure.
A few operational notes: The belts need cleaning weekly – compost dust builds up. The air exhaust filters need changing monthly. The heater elements are holding up well – no failures in six months.
Would I recommend this machine? Yes. For any waste-to-fertilizer operation, a belt dryer is essential. The DHG-1000 delivers consistent, dry product that farmers actually want."
Composted sludge is different from other materials. Here's why belt drying works:
Gentle handling: Screw or rotary dryers can break down compost structure. Belt dryers move material gently – no crushing, no degradation.
Uniform drying: The 5-layer design ensures consistent moisture throughout. The material spends equal time on each belt.
Low temperature: Belt dryers operate at 60-80°C. This preserves beneficial microorganisms in the compost. High-temperature dryers would kill them.
Flexible throughput: Belt speed adjusts from 10-60 minutes per layer. Johan can produce 15% moisture for bagging or 20% moisture for bulk delivery.
Scalable: Multiple units can be installed in parallel for higher capacity.
The DHG-1000 uses a 5-layer belt system:
1. Layer 1 (top): Material enters, hot air from below
2. Layer 2: Material drops, hot air from above
3. Layer 3: Material drops, hot air from below
4. Layer 4: Material drops, hot air from above
5. Layer 5 (bottom): Material drops, hot air from below
Each layer has independent air flow control. The material flips between layers, ensuring all sides are exposed to hot air.
Johan's settings for composted sludge:
Composted sludge produces dust when dry. Johan installed a dust collection system:
The dust collector cost an additional R150,000 (€7,500) – money well spent. The work environment is much cleaner.
The DHG-1000 uses electric heating. South Africa has relatively inexpensive electricity (compared to Europe). Johan's energy cost:
Very reasonable for the value added.
The DHG-1000 shipped from Qingdao to Port of Durban, South Africa.
Shipping time from Qingdao to Durban is about 25-30 days. The route goes through the South China Sea, past Singapore, across the Indian Ocean, and around the southern tip of Africa.
The machine was packed in a 40-foot container. Customs clearance in Durban took about 7 days. Total landed cost was about 25% higher than the FOB price.
The truck transport from Durban to Johannesburg was about 550km – roughly 6 hours.
For a waste management company producing compost from municipal sludge, belt drying is the standard.
Consider the DHG-1000 if:
Consider a larger model (DHG-2000) if:
For Johan's waste-to-fertilizer operation, the DHG-1000 was the right investment. It reduced moisture from 50% to 15-18%, doubled sales, and paid for itself in 4-5 months.
If you're processing composted sludge into fertilizer, don't sell it wet. Wet compost is heavy, sticky, and hard to handle. Farmers don't want it.
The DHG-1000 composted sludge belt dryer takes moisture from 50% down to 15-18%. The 5-layer design ensures uniform drying. Gentle handling preserves the compost structure. The result is a premium organic fertilizer that commands higher prices.
For waste-to-fertilizer, the math is simple: dry product = higher value = faster payback.
RICHI offers documentation in English, drying guidance, spare parts kits, and remote support. Contact RICHI Machinery through the website with your material type, input moisture, target output, and capacity for a recommendation. Tell them about your waste-to-fertilizer application – they can help you select the right dryer and settings for optimal results.
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