Sludge Dryer Manufacturer
As a leading sludge dryer manufacturer in India, AS Engineers is committed to reducing your carbon footprint while cutting operational costs and boosting productivity. With years of industry experience, we provide customized sludge drying solutions tailored to your unique needs.
Municipal Sludge
Our Sludge Dryers are used in the co-combustion of sewage sludge in municipal solid waste plants where the sludge is dried up to 90% dry solids.
Industrial Sludge
We supply Sludge Dryers that can process even the most toxic sludge from the ETP regardless of the industry type.
Byproduct Valorization
Optimal post-processing can be conducted from the Agri and Food waste through our Sludge Dryers.
Municipal Sludge
Sludge handling is one of the most complex problems that industries face in today’s world. Municipal, State, and Central laws make it harder for industries to handle the sludge in a way that meets the regulations. With AS Engineers’ Sludge Dryer, after being dried to approximately 90% dry solids, you can achieve the calorific value of your sewage sludge ranging from 1800 to 4500 kcal/kg; depending on its organic content.
You can use this dried sludge as a fuel inside the waste-to-energy plant, and can also be mixed with the municipal solid waste before it is combusted. What you get from combining a sewage sludge drying installation and a municipal solid waste plant is a waste-to-energy process environment for the sewage sludge drying line.
Usually, the municipal solid waste combustion process generates a heavy amount of steam. You can use this waste heat to operate the sewage sludge drying line. Therefore, the sewage sludge drying installation can be operated without external heating sources which significantly reduces the thermal energy costs. In broader terms, it greatly reduces the operating costs for the drying lines that have been installed.
We also offer a model where the exhaust gas volumes are extremely low and they can be treated thermally in the combustion process itself for the sludge drying line. This eliminates any biological or other multi-stage filter for treating the exhaust gas. The condensate that is produced should be discharged into the sewage system or should be treated locally as per the regulations.
Industrial Sludge
Textile Industries: It is one of the major contributors in sludge production today. The sludge from these wastewater treatment plants is often discarded in the environment which exposes it to flooding rainwater that causes soil and water contamination.
Therefore sludge handling for such applications becomes imperative for sustainable development.
With the rapid rise in environment pollution and increased energy consumption, sludge management and sludge drying is becoming an ever-increasing problem. This requires state-of-the-art drying solutions like AS Engineers’ Paddle Sludge Dryer.
For instance, the typical textile sludge having approximately 80% moisture content has a calorific value of >1500 kcal/kg. The textile sludge/clay mixtures carrying minimal moisture content can be used to make bricks, which are known to have compressive strengths and leaching behavior.
Pharmaceutical STPs: Pharma companies can fuel rapid environmental pollution by releasing toxic waste into the natural water resources. The hazardous and refractory organic pollutants contained in the sludge, if not handled responsibly, can cause high-levels of soil and water contamination. Pharmaceutical sludge contains relatively high levels of soluble organics, harmful antibiotics, and heavy metals.
Effective wastewater treatment facilities create a large amount of sludge. The disposal cost of this waste sludge is high and handling it is labor-intensive and potentially hazardous. Drying reduces the stream volume by a factor of 4 to 5, minimizing the disposal costs.
Byproduct Valorization
The accumulation and production of sludge in high quantities have a negative environmental impact, which require its treatment and valorization. We have developed a technology that is used in the wastewater sludge treatment called Thermal Drying process. This technology has the potential to produce bioenergy and biochars at a pilot and even at the industrial scale. Biochar can further be used as soil fertilizer or as adsorbent of heavy metals. This could be a part of the wastewater treatment facilities. Methods like pretreatment of raw sludge and co-digestion with other biomass waste have the ability to make the feedstock more accessible to the microorganisms, enhancing the biogas production yield used to power the Paddle Dryer. Our technology carries the potential to produce energy and to minimize the environmental impact in order to attain net zero discharge.
1. Alternate Fuels: Types of sludges varying across processes like municipal sewage plants, textile effluent treatment plants, pharmaceuticals sludge treatment plants, paper & pulp, food industry, can use their sludge as an alternate fuel option in boilers if the calorific value of your sewage sludge ranges from 1800 to 4500 kcal/kg; depending on its organic content.
2. Sludge Brick Making: The sludge can be added to clay bricks with a mass ratio of 1:10 since its strength is comparable to ordinary red bricks, and it contains a certain amount of energy. During the process of firing bricks, it can burn quickly and increase the heat in the kiln.
3. Bio-fiber Board: A series of physical and chemical changes (globulin denaturation) take place after heating, drying, and pressurization under alkaline conditions. Activated sludge resin or protein gel is created by this denaturation and the fibers are huddled together via press plates.
Unseen, Unheard, Unimaginable Cost Savings of Sludge dryer
Low Operating Cost
Our Paddle Dryers are energy efficient and run on indirect drying technology. This directly results in reduced operating costs.
Low Maintenance Cost
Ergonomic design and robust build quality ensures that little to no maintenance is required, saving time for other critical functions.
Low Installation Cost
Our Paddle Dryer has a compact and modular design. This directly corresponds to the dryer occupying less amount of space in your plant.
If your ETP or STP is running continuously, your sludge problem compounds every shift. Filter press cakes or belt press output still carry 65–85% moisture. Every kilogram of that wet sludge costs you approximately Rs 25 in authorised disposal at a TSDF facility – and CPCB and NGT enforcement of the Hazardous Waste Management Rules 2016 and Solid Waste Management Rules 2016 is getting tighter every year. The question is not whether to solve this. The question is whether you solve it at Rs 25 per kg or at Rs 5.45 per kg.
AS Engineers manufactures paddle-type sludge dryers that bring wet ETP sludge down from 85% moisture to 5–10% moisture through indirect conduction heat transfer, with no direct contact between the heating medium and the sludge. The result: 80–90% volume reduction, a dried product with a calorific value of approximately 3,500 kcal/kg, and a plant payback period of 12–13 months on a typical 500 kg/day installation. ISO 9001:2015 certified, Ahmedabad-manufactured, and sized for your specific sludge throughput.
What Is a Sludge Dryer and How Does It Work?
A sludge dryer is a thermal drying system that removes moisture from dewatered sludge cake, reducing its mass, volume, and disposal burden. The paddle dryer – the most efficient technology for sticky, abrasive, and variable-viscosity industrial sludge – works on indirect conduction: the heating medium (steam or thermic fluid) circulates through hollow wedge-shaped paddles and hollow shafts, transferring heat through metal surfaces into the sludge without any direct contact or hot air.
Two counter-rotating shafts carry these wedge-shaped paddles. As they intermesh and rotate, the sludge is continuously turned, exposed to fresh hot surface area, and moved progressively from the inlet to the outlet. The self-cleaning action of the intermeshing paddles prevents material buildup. The enclosed design contains vapours for downstream treatment. The result is a compact, continuous-operation drying system with a smaller footprint than rotary or belt dryers of equivalent capacity.
Why Paddle-Type Drying Is the Right Technology for ETP and STP Sludge
Most sludge is sticky. At 65–75% moisture, it does not flow freely – it smears, bridges, and sticks to surfaces. This is where belt dryers and rotary drum dryers lose efficiency: the sludge sticks to the belt or tumbles unevenly in the drum, requiring large residence times and high airflows that increase off-gas treatment costs.
The paddle dryer’s wedge-shaped, intermeshing paddles handle sticky and abrasive sludge directly. There is no belt to replace, no drum seals to maintain, and no high-volume airstream requiring complex scrubbing. Off-gas volume is low — typically 2–5% of the sludge mass as water vapour and entrained fines — which significantly reduces the size and cost of the downstream vapour treatment system. For hazardous industrial sludge where VOC containment matters, the fully enclosed, vapour-tight design also satisfies the requirements under the HW Management Rules 2016 for contained thermal treatment.
Technical Specifications
| Parameter | Range |
|---|---|
| Inlet moisture content | 40–85% (w/w basis) |
| Outlet moisture content | 5–15% (or as low as 1–2% for specific applications) |
| Heating medium | Steam (up to 14.06 kg/cm²) or thermic fluid (up to 400°C) |
| MOC — contact parts | SS 304, SS 316, Duplex Steel 2205 |
| MOC — shell | Carbon steel, SS 304, SS 316 |
| Operation mode | Continuous (standard) or batch |
| Pressure conditions | Atmospheric, vacuum, or pressurised |
| Throughput | Sized per project requirement (pilot to large-scale) |
| Shaft design | Hollow dual counter-rotating shafts with hollow wedge-shaped paddles |
| Self-cleaning | Yes — intermeshing paddle geometry |
| Vapour containment | Fully enclosed, vapour-tight design available |
| Certification | ISO 9001:2015 |
Dryer sizing is done on a project-specific basis from your sludge data – feed moisture, daily tonnage, operating hours, and heat source availability. Fill out our sludge dryer questionnaire to begin the sizing process.
Sludge Types We Handle
Our paddle-type sludge dryers are designed for the full range of industrial and municipal sludge streams:
- ETP sludge from chemical, pharmaceutical, textile, and food processing plants — including toxic, heavy-metal-bearing, and high-moisture-variability streams
- STP sludge from municipal and industrial sewage treatment plants — including primary sludge, secondary (activated) sludge, and digested sludge blends
- Paper mill sludge — fibrous, high-ash content, variable consistency
- Pharma process sludge — requiring SS 316L contact parts and full vapour containment
- Food and agri-processing sludge — high organic content, odour-controlled enclosure
- Livestock and biogas plant effluent sludge — for farms and biogas installations handling animal waste
If your sludge stream has unusual characteristics — very high silica, extreme stickiness, or fluctuating feed rates — contact our engineering team with your sludge analysis data. We design around your material, not around a standard model.
The Three-Step Cost Transformation
Most ETP-running plants today follow this path:
- Dewater sludge with belt press or filter press (output: 65–75% moisture cake)
- Store wet cake in containers or designated area (labour, space, odour)
- Transport to authorised TSDF facility and pay for disposal (Rs 15–30/kg depending on hazard classification and distance)
With a paddle sludge dryer, step 3 changes fundamentally:
- Dewater sludge with belt press or filter press (same as before)
- Feed belt press output into the paddle dryer (continuous, 8 hrs/day operation)
- Use dried sludge powder — with calorific value approximately 3,500 kcal/kg — as a supplemental fuel in your boiler, or sell/transfer at significantly lower cost
You have reduced the mass requiring TSDF disposal by 80–90%. What previously cost Rs 60 lakhs per year to dispose now costs a fraction – and in many plants, the dried product pays for itself.
What Happens to Dried Sludge — Is It Still a Disposal Problem?
This is the question most plant managers ask before they commit to a sludge dryer. The answer depends on your sludge classification, and it is worth understanding clearly.
For non-hazardous municipal and domestic STP sludge dried to biosolid quality, the FSSM Policy 2017 and NMCG guidelines support co-composting, land application, and use in construction materials. For industrial ETP sludge, the Hazardous Waste Management Rules 2016 govern end-use. If the sludge is classified as hazardous, disposal at an authorised TSDF is still required — but you are now disposing of 2 tonnes per day instead of 10 tonnes per day. Your disposal contract and logistics costs drop by 80%.
For industrial sludge with a measured calorific value of 2,000–4,000 kcal/kg, co-processing in cement kilns or co-combustion as boiler supplemental fuel is a viable route that many plants are already using. Discuss your sludge characterisation data with our team early — the end-use pathway affects the required outlet moisture and design of the vapour treatment system.
Industries Where Our Sludge Dryers Are Installed
AS Engineers supplies sludge dryers across industries that operate ETPs and STPs as a regulatory requirement. Typical installation sectors include:
- Chemical and petrochemical (process sludge, reaction byproduct sludge)
- Pharmaceutical (API manufacturing ETP sludge, aqueous waste streams)
- Textile and dyeing (high-BOD sludge, colour-bearing ETP output)
- Food processing and dairy (organic-rich STP/ETP sludge, high-moisture cake)
- Paper and board (fibrous sludge, black liquor solids)
- Fertilizer and agrochemicals (process waste sludge, reaction cake)
- Municipal corporations and Urban Local Bodies (STP biosolids under AMRUT 2.0 and NMCG funding)
For municipal and ULB applications, our sludge dryers integrate with the broader sludge management and treatment system at STPs, reducing biosolid mass before landfill or co-processing.
Why Choose AS Engineers for Your Sludge Dryer
AS Engineers has designed and manufactured paddle dryers from our Ahmedabad facility since 1997. We are not an agent or distributor – every dryer is engineered and fabricated in-house, which means we can modify shaft geometry, paddle pitch, or housing dimensions based on your specific sludge behaviour.
Key points relevant to your vendor evaluation:
- Indirect heat transfer throughout – heating medium never contacts the sludge, which matters for pharma, food, and hazardous sludge applications
- Pilot trial available – we offer a pilot plant facility for offsite and onsite trials so you can validate drying performance before committing to a full-scale installation
- SS 304, SS 316, and Duplex Steel contact parts for corrosive sludge streams
- Vapour-tight enclosure for hazardous or VOC-bearing sludge under HW Rules 2016
- Dedicated after-sales team for maintenance, shaft/paddle replacement, and seal replacement
- Documentation: material test certificates, dimensional inspection records, performance test certificates, and ISO 9001:2015 quality records supplied with every dryer
We are based at Plot 514, Phase-II, GIDC Vatva, Ahmedabad. Our engineers are available for site visits in Gujarat and nearby states at short notice.
Frequently Asked Questions
What inlet moisture can the AS Engineers paddle sludge dryer handle?
Our paddle sludge dryers are designed to handle inlet moisture content of up to 85% on a weight/weight basis. The typical range for ETP filter press or belt press output is 65–75% moisture, which falls well within our standard design range. Outlet moisture is adjustable from 15% down to 5% or lower depending on the required end-use or disposal standard.
How long does it take to get a payback on a sludge dryer investment?
On a typical 500 kg/day installation operating 8 hours per day and 300 days per year, with current disposal costs around Rs 25/kg and power at Rs 10/kWh, our project feasibility model shows annual savings of Rs 27,12,000 against an operating cost of Rs 13,08,000, with a payback period of 12–13 months. Your actual payback depends on your disposal rate, sludge quantity, and available heat source. Provide us with your sludge data and we will prepare a site-specific feasibility calculation at no cost.
What is the difference between direct and indirect sludge drying?
In indirect (conduction) drying – which is what our paddle dryers use – the heating medium circulates inside hollow shafts and paddles, and heat transfers through metal surfaces into the sludge. The sludge never contacts steam, thermic fluid, or hot air directly. In direct (convection) drying, hot gas or air is blown through the sludge. Indirect drying is preferred for industrial ETP sludge because it produces a low-volume off-gas stream, making downstream vapour treatment simpler and cheaper. It also avoids dust explosion risk from fine dried particles that can occur with high-velocity air drying.
Can the dried sludge be used as boiler fuel?
Industrial ETP sludge, once dried to 5–10% moisture, typically has a calorific value in the range of 2,000–4,000 kcal/kg depending on organic content. Our project data shows approximately 3,500 kcal/kg for mixed ETP sludge from chemical and pharmaceutical plants. Co-firing this material with coal at 10–15% substitution is practised in boilers already operating in several chemical clusters. Verify the calorific value and ash content of your specific sludge before committing to a boiler co-firing design. We can guide you through the characterisation process.
What regulatory framework governs sludge disposal in India, and how does drying help?
The primary regulations are the Hazardous Waste (Management, Handling and Transboundary Movement) Rules 2016 under the Environment Protection Act, the Solid Waste Management Rules 2016, and NGT directives requiring authorised treatment before disposal. CPCB has also issued guidelines on sludge characterisation and disposal options. Thermal drying reduces sludge mass by 80–90%, which directly reduces the volume that must be transported and disposed of at authorised TSDF facilities — reducing compliance cost and logistics risk. For municipal STPs, NMCG and AMRUT 2.0 programmes are funding sludge management infrastructure, making this an active procurement window for Urban Local Bodies.
Request a Quote or Feasibility Assessment
Tell us your sludge quantity (kg/day), current moisture content, disposal cost per kg, and available heat source (steam or thermic fluid). We will send you a preliminary sizing and feasibility calculation within 48 hours, before any commercial discussion.
Request a Free Feasibility Calculation | Call: +91 99090 33851 | Email: info@theasengineers.com
For detailed paddle dryer technical information and application guides, visit sludgedryer.in.
Paddle Sludge Dryer Trial
Boost your industry's performance and save costs with our paddle dryer. Our dryers are the most efficient and effective on the market, and we can help you reduce your sludge disposal costs by up to 50%.