Jiangsu Hengfeng Fine Chemical Co., Ltd.

A municipal wastewater treatment plant recently faced challenges in its sludge dewatering system, where belt filter press performance had declined, resulting in high sludge moisture, excessive polymer consumption, and unstable cake formation. By introducing Hengfeng Cationic 9802 and optimizing the conditioning process, the plant significantly improved dewatering efficiency, reduced operating costs, and achieved stable, continuous operation. Site Overview Industry: Municipal wastewater treatmentSludge type: Mixed primary and secondary (biological) sludgeTreatment capacity: 1,800–2,200 m³/day (sludge processing line) Sludge characteristics:High organic content, poor dewaterability, sludge concentration 0.8–1.2%, with high extracellular polymeric substances (EPS), making flocculation difficult. Dewatering system configuration: · Belt filter press units · Polymer prepared at 0.1% concentration · Gravity thickening + pressure zone dewatering   Initial Issues · Sludge cake moisture content remained high at 82–85%  · Filtrate turbidity was high, with visible solids carryover · Flocs were small and weak, breaking easily under shear · Polymer consumption was high, yet performance remained unstable · Belt blinding and clogging occurred frequently, increasing cleaning frequency   Problem Analysis After on-site evaluation, several key issues were identified: 1. Inadequate Polymer Performance The previously used flocculant had insufficient charge density and molecular weight, leading to poor charge neutralization and weak bridging ability. Flocs formed were loose and easily destroyed in the press zone. 2. Poor Sludge Conditioning The sludge was not fully conditioned before entering the belt press. Mixing intensity and reaction time were insufficient, resulting in incomplete floc formation. 3. High Organic Content Interference Municipal biological sludge contains high levels of EPS and organic matter, which increases viscosity and water retention, requiring stronger cationic polymers for effective dewatering. 4. Non-Standardized Operation Polymer preparation and dosing lacked consistency. Solution aging time was insufficient, and operators relied heavily on experience rather than structured control, leading to fluctuating performance.   Technical Solution Optimized Polymer Selection Hengfeng recommended Cationic Polyacrylamide 9802, featuring: · Optimized cationic charge density · High molecular weight for strong bridging · Excellent adaptability to biological sludge The product significantly improved floc size, density, and resistance to shear.   Process Optimization Polymer preparation: · Concentration increased to 0.15%  · Aging time extended to 45–60 minutes to ensure full dissolution Dosage control: · Adjusted to 4.0–5.5 kg/t DS (dry sludge)  · Fine-tuned based on cake dryness and filtrate clarity Mixing optimization: · Improved flocculation tank mixing to ensure sufficient reaction time · Reduced shear before entering the belt press   Equipment Operation Adjustment · Optimized belt speed and pressure distribution · Balanced gravity drainage and الضغط zones · Reduced over-squeezing, which previously caused floc breakage   Operator Training & Standardization Hengfeng technical team provided on-site guidance to: · Standardize polymer preparation procedures · Establish visual floc evaluation standards · Train operators to adjust dosage based on real-time performance · Implement routine monitoring and record-keeping This ensured stable and repeatable operation.   Performance Results After implementation and continuous monitoring: · Sludge cake moisture reduced to 75–78%  · Filtrate became clear, with significantly reduced suspended solids · Polymer consumption decreased by 15–20%  · Flocs became large, dense, and resistant to shear · Belt clogging was eliminated, reducing downtime and cleaning frequency · Overall system achieved stable, continuous operation   Project Outcome Through optimized polymer selection, improved sludge conditioning, and standardized operation, Hengfeng successfully enhanced belt filter press performance in municipal sludge dewatering. This case highlights that effective sludge dewatering depends not only on equipment, but also on selecting the right flocculant and implementing proper process control.

Hengfeng PAM test- Electronic factory wastewater   Electronic manufacturing wastewater exhibits distinct characteristics primarily due to complex chemical processes involved. Its key features include: l  Elevated Heavy Metal Content‌: Contains significant concentrations of toxic heavy metals such as lead (Pb), mercury (Hg), cadmium (Cd), nickel (Ni), arsenic (As), and copper (Cu), originating from etching, plating, and component manufacturing processes‌;   l  High Levels of Per- and Polyfluoroalkyl Substances (PFAS)‌: Includes both legacy compounds like perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), as well as emerging short-chain PFAS (e.g., PFBA, PFHxA) and novel fluorinated compounds (e.g., hexafluoroisopropanol, bistriflimide). These stem from fluoropolymer coatings, circuit boards, and photolithography chemicals‌;     l  Presence of Specific Organic Solvents and Additives‌: Characterized by high concentrations of tetramethylammonium hydroxide (TMAH, 5–66 g/L), glycerol (5–66 g/L), pyrazole, acetone, and other organic residues used in cleaning, degreasing, and photoresist stripping;   l  Inorganic Contaminants and High Salinity‌: Contains fluorides (e.g., calcium fluoride, CaF₂), ammonium, sulfates, and exhibits variable pH (often alkaline or acidic), alongside elevated total dissolved solids (TDS) and conductivity due to chemical additives and process rinsates;   l  Complexity and Persistence‌: Comprises a mixture of persistent organic pollutants (POPs), dioxin-like compounds, polycyclic aromatic hydrocarbons (PAHs), and halogenated organics. These contaminants are often bioaccumulative, resistant to conventional degradation, and pose significant ecotoxicity risks‌ These characteristics collectively contribute to high chemical oxygen demand (COD), low biodegradability (BOD/COD ratio typically 0.11–0.15), and necessitate advanced treatment strategies.   Materials Needed Electronic factory wastewater sample Polyacrylamide powder (prepared as per the previous guideline) Beakers or containers Magnetic stirrer pH meter Flocculation testing apparatus (e.g., jar test apparatus) Chemical dosing equipment   Testing Procedure 1. Sample Collection: Receive electronic manufacturing wastewater from partner. Check the background and demand of partner. 2. Preparation of Polyacrylamide powder: Ensure that you have a prepared solution of polyacrylamide, as discussed in the previous procedure. This can be used for the flocculation process. 3. Flocculation Test (Jar Test): Setup: Prepare a series of beakers for different doses of polyacrylamide Add Wastewater: Add equal volumes of the wastewater sample to each beaker (in this case, 50 mL). Add Polyacrylamide: Add the specified amount of polyacrylamide to corresponding beakers. Mixing: Stir the solutions at a rapid speed (in this case, 200 rpm) for about 1-2 minutes, then stop for an additional 3 minutes to allow floc formation.     4. Post-Treatment Analysis: Visual Assessment: Observe and note the clarity and color of the treated water. pH Measurement: Measure the final pH of the treated samples. Safety Precautions Wear appropriate PPE (gloves, goggles, lab coat) while handling wastewater samples and chemical agents. Handle all chemicals and equipment according to safety guidelines. Conclusion This procedure provides a systematic approach to assessing the effectiveness of polyacrylamide on treating electronic manufacturing wastewater. It's important to optimize the concentration of polyacrylamide based on the characteristics of the specific wastewater being treated for best results.

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The key challenges are difficult demulsification, toxin removal and standard compliance—stable colloid from emulsified oil paralyzes biochemical systems, and heavy metal-organic complexes cannot be removed by conventional precipitation. HENGFENG POLYMER have successfully solved these industry pain points through scientific lab small-scale tests and targeted on-site commissioning, realizing efficient and stable treatment of machining wastewater with remarkable decolorization and pollutant removal effects. The Classic Treatment Process for Machining Wastewater The core process adopts physical-chemical combined technology for step-by-step pollutant removal: Oil Separation → Chemical Enhanced Air Flotation → Aerobic Biodegradation → Secondary Sedimentation → Effluent Discharge The air flotation tank stage is the key pre-treatment step. Chemical agents are dosed in sequence to achieve efficient purification: Caustic soda flakes: Adjust pH value to neutralize acidity Decolorant: Destroy organic molecular structures and remove chroma PAM flocculant: Agglomerate micro flocs into large particles for solid-liquid separation This chemical enhancement effectively removes emulsified oil, colloid, chroma and partial heavy metal ions, creating favorable conditions for subsequent biochemical treatment and avoiding system poisoning. Lab Small-Scale Test: Verify Feasibility with Exact Data Raw Water Quality Index (Machining Wastewater) Index Value/Phenomenon Core Diagnosis Appearance White turbidity Severe emulsification, rich colloid pH 5-6 Acidic, inhibiting biochemical reaction COD 35.2mg/L Low base, organic pollution Chroma 94 degrees High, from metal ions/suspended solids Scientific Dosing Process Add composite decolorant: 250g/ton Dose caustic soda flakes: Adjust pH to 7-8, 80g/ton Flocculation with anionic PAM: 1g/ton Test Results Effluent becomes clear and transparent with significant floating sludge formation Chroma reduced sharply from 94 to 13 degrees (outstanding decolorization effect) COD remains stable at a low level (no obvious change due to low raw water base) Emulsified oil and colloid are effectively removed, meeting biochemical treatment inlet requirements On-Site Commissioning: Optimize Scheme for Actual Production Conditions Direct application of the lab scheme to the production line led to poor floc formation and solid-liquid separation due to raw water concentration fluctuation and complex on-site water quality. We made two targeted optimizations for actual production: Decolorant Dosage Optimization Flocculant Type Replacement Adjust composite decolorant dosage to 0.2% (2kg/ton)—effectively adapt to water volume fluctuation and water quality complexity in mass production, and strengthen the removal of refractory organic matter and chroma pollutants. Replace anionic PAM with cationic PAM—aim at negatively charged colloid and fine suspended solids in production wastewater, enhance flocculation efficiency through electric neutralization, and significantly promote sludge aggregation and solid-liquid separation. Final Achievements: Stable Up-to-Standard Discharge for Production System Effluent Quality: Clear and transparent, chroma stably up to standard, no emulsification phenomenon Sludge Property: Good settleability and floatability, easy for subsequent treatment and disposal COD Stability: Remains at a low level stably, ensuring safe operation of the subsequent biochemical system System Adaptability: Strong anti-shock load capacity, adapt to real-time water quality/volume fluctuation in machining production Cost Control: Optimized agent ratio, no excessive dosing, realizing economical and efficient treatment Technical Highlights of This Solution Targeted Process Design: Take chemical enhanced air flotation as the core, accurately solve the key problem of demulsification and pollutant removal for machining wastewater Lab-Field Integration: Based on lab test data, optimize the scheme according to actual production conditions to avoid disconnection between test and application Efficient Agent Matching: Adjust agent type/dosage according to pollutant charge property, realize efficient flocculation through electric neutralization Stable Operation Guarantee: The optimized process has strong adaptability, ensuring long-term up-to-standard discharge and reducing enterprise environmental risk Customized Machining Wastewater Solutions For You HENGFENG POLYMER focus on industrial wastewater treatment with rich experience in machining, metal processing and mechanical manufacturing industries. Our one-stop service covers: Free Lab Testing: Accurate analysis of your wastewater quality index Custom Process Design: Formulate targeted treatment scheme according to production scale On-Site Commissioning & Optimization: Adjust the scheme in real time to ensure treatment effect Long-Term Operation Maintenance: Professional after-sales service for stable system operation Contact Us For A Free Quotation Official website: www.pampolyacrylamide.com LinkedIn:www.linkedin.com/company/jiangsu-hengfeng-fine-chemical-co-ltd HENGFENG POLYMER customize exclusive and economical machining wastewater treatment solutions for your enterprise, helping you achieve green production and meet international environmental standards!