Corrosion-Resistant Solution: HONGTUO Netzsch Alternative Screw Pumps in a Chinese Food Waste Treatment Plant

As China’s food waste treatment industry booms, biogas slurry treatment — a core process — demands exceptional corrosion resistance and stability from conveying equipment. Netzsch screw pumps have become the preferred choice for many food waste treatment plants due to their high conveying efficiency. However, some conventional Netzsch screw pumps feature cast iron suction chambers and discharge bodies. In the strongly acidic environment of biogas slurry in food waste facilities, these components often suffer from corrosion and rust-through after a period of use. When the customer reached out to us, we customized screw pumps with all wetted metal parts made of 304 stainless steel based on on-site conditions. Since the replacement, there has been no recurrence of rust-through issues.

Customer Background and Core Dilemmas

Located in a provincial capital city in eastern China, this food waste treatment plant is a key local environmental protection project, processing 300 tons of food waste daily. It is primarily responsible for the collection, harmless treatment, and resource utilization of food waste from surrounding catering businesses and residential communities. Its core processes include waste sorting, anaerobic fermentation, biogas slurry treatment, and organic fertilizer processing. The plant initially operated 8 sets of Netzsch NEMO series screw pumps (mainly models NM053 and NM076) for biogas slurry conveying, which are tasked with lifting, transporting, and subsequent treatment of biogas slurry after anaerobic fermentation.

Biogas slurry generated from the anaerobic fermentation of food waste is highly corrosive (pH 3.5-4.5) due to its high content of organic acids and sulfides. However, the Netzsch screw pumps used at the plant were equipped with conventional cast iron suction chambers and discharge bodies — standard components commonly used by Netzsch. While these parts meet the requirements of general working conditions, they cannot withstand the strong acidic corrosion of biogas slurry. After only 6 months of use, the equipment exhibited obvious abnormalities:

● Frequent corrosion and rust-through: Large rust patches appeared on the surfaces of the suction chambers and discharge bodies, gradually penetrating and rusting through. This caused biogas slurry leakage, which not only contaminated the on-site environment but also required emergency shutdowns for repairs. Each leakage resulted in a 2- to 3-day production interruption;

● Skyrocketing operation and maintenance (O&M) costs: On average, a set of cast iron suction chambers and discharge bodies needed replacement every 6 months, with a single set costing up to 12,000 RMB (approximately 1,650 USD). Annual replacement costs exceeded 200,000 RMB (around 27,500 USD). Additionally, frequent shutdowns led to delayed biogas slurry treatment, putting the plant at risk of failing environmental compliance standards;

● Shortened equipment service life: Corrosion not only damaged the suction chambers and discharge bodies but also spread to internal pump components, accelerating wear on screws and stators. The service life of the entire pump unit was 40% shorter than expected, further increasing equipment replacement costs.

To fully resolve the corrosion issue, avoid shutdown losses, and mitigate environmental risks, the food waste treatment plant contacted HONGTUO Machinery through industry referrals, seeking a customized alternative screw pump solution to replace its existing Netzsch equipment.

HONGTUO On-Site Diagnosis and Customized Alternative Solution

HONGTUO’s technical team promptly visited the site to conduct a comprehensive diagnosis of the original Netzsch screw pumps’ operating conditions and corrosion issues. Combining the strong acidic properties of food waste biogas slurry, conveying pressure (0.8-1.2MPa), and flow requirements (30-50m³/h), we developed a customized alternative solution focused on "corrosion resistance first, precise compatibility, and cost-efficiency." The core breakthrough was optimizing the material of wetted metal components. The specific solution is as follows:

● Comprehensive material upgrade: Abandoning Netzsch’s conventional cast iron, all wetted metal parts of the alternative screw pumps — including suction chambers and discharge bodies — are made of 304 stainless steel. 304 stainless steel offers excellent acid and corrosion resistance, effectively resisting erosion from organic acids and sulfides in biogas slurry and fundamentally eliminating rust-through issues;

● Precise compatibility with the original system: Strictly adhering to the dimensional parameters, installation interfaces, and operating specifications of Netzsch NEMO NM053 and NM076 series screw pumps, the alternative pumps ensure 100% compatibility with the plant’s existing installation bases and pipeline systems. They can be directly disassembled and replaced without modifying on-site facilities, reducing shutdown time for modifications;

● Core component optimization: To address the presence of small impurities in biogas slurry, we optimized the structural design of screws and stators. Wear-resistant and corrosion-resistant rubber stators are paired with 304 stainless steel screws, enhancing the equipment’s wear and corrosion resistance and extending the service life of the entire pump unit;

● Cost optimization and after-sales support: The overall procurement cost of HONGTUO’s alternative screw pumps is 35% lower than that of original Netzsch pumps. We also provide a 1-year quality guarantee, a professional after-sales team, 24-hour technical support, on-site fault response within 24 hours, and regular on-site inspections to ensure stable equipment operation.

Post-Replacement Performance: Corrosion Problem Solved, Significant Cost Reduction and Efficiency Improvement

In May 2024, the food waste treatment plant introduced HONGTUO’s customized Netzsch alternative screw pumps, gradually replacing all 8 original Netzsch units. After 9 months of on-site operation, the performance exceeded expectations, completely resolving the long-standing corrosion issue:

● No corrosion or rust-through: The wetted metal parts (suction chambers and discharge bodies) of the replaced screw pumps are made of 304 stainless steel. After 9 months of continuous operation in strongly acidic biogas slurry, there are no rust spots, corrosion marks, rust-through, or leakage — the equipment operates stably;

● Improved production continuity: The equipment has zero leakage and zero corrosion-induced shutdowns. The biogas slurry conveying process operates continuously and stably, ensuring the smooth flow of the food waste treatment process and eliminating the risk of environmental non-compliance due to delayed biogas slurry treatment;

● Excellent adaptability and compatibility: The alternative screw pumps are fully compatible with the plant’s existing pipelines and control systems. Their operating parameters (flow rate, pressure) are consistent with the original Netzsch pumps, meeting the core requirements of biogas slurry conveying. No adjustments to operating procedures are needed, allowing employees to adapt quickly.

● Significant O&M cost reduction: Frequent replacement of suction chambers and discharge bodies is no longer necessary, reducing annual O&M costs from 200,000 RMB (about 27,500 USD) to 80,000 RMB (around 11,000 USD) — a 60% savings. Equipment wear is slowed, and the service life of the entire pump unit is expected to extend to more than 5 years, significantly lowering equipment replacement costs;

Customer Testimonial & Case Summary

The plant’s O&M director stated: “HONGTUO’s Netzsch alternative screw pumps have completely solved our corrosion problems. Previously, the cast iron suction chambers and discharge bodies of the original Netzsch pumps rusted through frequently, which not only disrupted production but also increased costs significantly. HONGTUO’s customized alternative pumps, made of 304 stainless steel, offer strong adaptability and excellent corrosion resistance. They have operated for 9 months without any faults, greatly reducing our O&M pressure and costs. They are a cost-effective, high-quality alternative, and we will continue to select HONGTUO’s products for our subsequent expansion projects.”

This case fully demonstrates that HONGTUO’s customized Netzsch alternative screw pumps — through material upgrades and precise compatibility — perfectly address the corrosion defects of conventional Netzsch components in the harsh, strongly acidic biogas slurry environment of food waste treatment plants. Compared to original equipment, HONGTUO’s alternative pumps offer significant advantages in corrosion resistance, service life, and cost control, while maintaining excellent adaptability and stability. They provide a replicable corrosion solution for food waste treatment plants and biogas slurry projects worldwide. Whether you are facing issues such as Netzsch screw pump corrosion, high O&M costs, or frequent shutdowns, HONGTUO Machinery can deliver customized alternative solutions tailored to your on-site conditions, helping your enterprise reduce costs, improve efficiency, and ensure stable production. Global customers are welcome to contact us for exclusive adaptation solutions.