Jiangsu Hengfeng Fine Chemical Co., Ltd.

Slurry Shield Tunneling Project: Sydney Cross-River Tunnel Construction During the construction of the Sydney cross-river tunnel, the slurry shield tunneling generated a large amount of waste concrete slurry characterized by high water content and ultra-high clay particle content. This kind of slurry had long been a tough problem for construction teams due to the difficulty in solid-liquid separation and low treatment efficiency. To solve this problem, researchers carried out flocculation and dehydration tests on the slurry using APAM in combination with polyaluminum chloride (PAC) and polyaluminum ferric chloride (PAFC). The test results showed that APAM outperformed PAFC and PAC alone in terms of slurry dehydration effect, and the composite flocculant of PAFC + APAM achieved the optimal conditioning effect on the waste slurry. When the optimal dosage of PAFC solution was 33g/L and that of APAM solution was 233g/L (with the dry matter dosages being 1.6g/L and 0.466g/L respectively), the slurry dehydration rate reached 29.6% within 90 minutes, and the turbidity of the separated free water was reduced to 62.0 NTU. The adsorption and bridging effect of APAM's long polymer chains was the core driving force behind the efficient dehydration. This application not only ensured the smooth progress of the tunnel construction but also provided reusable clear water, which reduced the project's demand for fresh water resources.

  Testing the effectiveness of polyacrylamide emulsion on treating printing wastewater involves several steps, from sample collection to analysis. Here is a general procedure you can follow: Materials Needed Printing wastewater sample Polyacrylamide emulsion (prepared as per the previous guideline) Beakers or containers Magnetic stirrer pH meter Turbidity meter or nephelometer Flocculation testing apparatus (e.g., jar test apparatus) Filtration apparatus Chemical dosing equipment Spectrophotometer (for further analysis of contaminants if needed) Testing Procedure 1. Sample Collection: Collect samples of printing wastewater in clean containers. Ensure that the samples are representative of the wastewater being treated. 2. Initial Characterization: Measure pH: Use a pH meter to determine the initial pH of the wastewater. Measure Turbidity: Use a turbidity meter to determine the initial turbidity level of the wastewater. Visual Assessment: Examine the color and clarity of the wastewater. Note any visible contaminants. 3. Preparation of Polyacrylamide Emulsion: Ensure that you have a prepared emulsion of polyacrylamide, as discussed in the previous procedure. This can be used for the flocculation process. 4. Flocculation Test (Jar Test): Setup: Prepare a series of beakers for different doses of polyacrylamide emulsion (e.g., 0, 5, 10, 15, 20 mg/L). Add Wastewater: Add equal volumes of the wastewater sample to each beaker (e.g., 500 mL). Add Polyacrylamide: Add the specified amount of polyacrylamide emulsion to corresponding beakers. Mixing: Stir the solutions at a rapid speed (e.g., 200 rpm) for about 1-2 minutes, then slow down to a lower speed (e.g., 30 rpm) for an additional 15-20 minutes to allow floc formation.       5. Settling Time: Stop stirring and allow the flocs to settle for a predetermined time (e.g., 30 minutes to 1 hour). 6. Post-Treatment Analysis: Measure Turbidity: Measure the turbidity of each sample after settling using the turbidity meter. Visual Assessment: Observe and note the clarity and color of the treated water. pH Measurement: Measure the final pH of the treated samples. Filtration: Filter the supernatant from each beaker to evaluate the effectiveness of the flocculating agent further. 7. Additional Testing (if needed): Use additional tests such as COD (Chemical Oxygen Demand), BOD (Biochemical Oxygen Demand), or specific contaminant analysis (e.g., heavy metals, dyes) using a spectrophotometer to assess the effectiveness of the treatment further and compare results with the initial values. 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 emulsion on treating printing wastewater. It's important to optimize the concentration of polyacrylamide based on the characteristics of the specific wastewater being treated for best results.

HENGFENG Floc Application Process of Flocculant (PAM) in Heavy Metal-Contaminated Soil Leaching Remediation 1. Pretreatment: Wastewater pH Adjustment and Homogenization Purpose Citric acid is acidic (pH ≈ 2-3), while polyacrylamide (PAM), especially HENGFENG Floc non-ionic or HENGFENG Floc anionic types, exhibits optimal flocculation performance under neutral to weakly alkaline conditions. Meanwhile, pH adjustment can disrupt part of the heavy metal-citric acid complexes, releasing free heavy metal ions (e.g., Co²⁺) or forming hydroxide/carbonate micro-precipitates, thereby creating favorable conditions for subsequent flocculation. Operation Add quicklime (CaO) or sodium hydroxide (NaOH) into the leachate storage tank to adjust the pH to 7.0-8.5, with real-time monitoring via an online pH meter. Simultaneously, start the agitator at a rotational speed of 150-200 r/min to homogenize the wastewater, preventing local pH fluctuations from affecting flocculation efficiency. 2. PAM Selection and Dissolution Preparation Selection Basis The wastewater in this case contains negatively charged soil colloids (due to the negative charge on the surface of soil clay minerals) and heavy metal complexes (mostly negatively charged or neutral). Therefore, anionic PAM (with a molecular weight of 8-12 million Da) is preferred. The carboxyl groups (-COO⁻) on its molecular chains can promote agglomeration through "charge neutralization" (adsorbing negative charges on the surface of soil colloids) and "bridging effect" (connecting multiple micro-particles). Compared with HENGFENG Floc  non-ionic PAM, it has higher flocculation efficiency, and its cost is lower than that of HENGFENG Floc cationic PAM. Dissolution Preparation Dissolution Water: Use deionized water or clarified tap water (to avoid precipitation caused by the reaction of Ca²⁺ and Mg²⁺ in hard water with PAM). Concentration Control: Mix HENGFENG Floc PAM powder with water at a mass ratio of 0.1%-0.3%, i.e., add 1-3 g of HENGFENG Floc PAM to 1 L of water. Dissolution Method: First add water into the stirring tank, then slowly sprinkle PAM powder (to prevent caking). Control the stirring speed at 80-100 r/min and the stirring time at 30-60 minutes until the solution becomes transparent and viscous (with no visible particles to the naked eye). If dissolution is insufficient, undissolved PAM particles will form "fish eyes" in the wastewater, which will instead reduce flocculation efficiency. 3. PAM Dosing and Reaction (Flocculation Reaction Tank) Dosing Method Adopt "metering pump dripping" to slowly inject the prepared PAM solution into the flocculation reaction tank at a final dosage of 1-5 mg/L (i.e., 1-5 mg of effective PAM component per liter of leachate). The dosing port is installed in front of the stirring impeller to ensure rapid mixing with the wastewater. Reaction Control (Two Stages) Rapid Mixing Stage: Control the stirring speed at 200-300 r/min for 1-2 minutes. The purpose is to achieve instant and uniform contact between the PAM solution and the wastewater, enabling PAM molecules to quickly adsorb onto the surface of colloidal particles. Slow Flocculation Stage: Reduce the rotational speed to 50-80 r/min and maintain it for 10-15 minutes. This stage is critical for "bridging and agglomeration". Slow stirring can avoid damaging the flocs being formed, allowing small particles to gradually aggregate into large flocs (visible "alum flowers") with a particle size of ≥ 100 μm. Meanwhile, the flocs can adsorb cobalt complexes or free Co²⁺ in the wastewater. 4. Solid-Liquid Separation (Sedimentation Tank / Clarification Tank) Process Selection Due to the high density of the flocs (containing heavy metal precipitates), vertical flow sedimentation tanks or inclined tube sedimentation tanks are adopted, as they occupy less area and have higher separation efficiency. Operating Parameters Control the hydraulic retention time (HRT) of the sedimentation tank at 1-2 hours and the upward flow velocity at 1.5-2.5 mm/s. This ensures that the flocs have sufficient time to settle to the bottom of the tank, forming "sludge" (containing heavy metal precipitates, soil colloids, and PAM flocs), while the upper layer becomes clarified liquid. Key Function Through this step, the removal rate of suspended solids (SS) in the wastewater can reach over 90%. At the same time, heavy metals such as cobalt settle along with the flocs, significantly reducing the heavy metal concentration in the clarified liquid and laying a foundation for subsequent up-to-standard discharge or advanced treatment. 5. Subsequent Treatment: Disposal of Sludge and Clarified Liquid Sludge Treatment The heavy metal-containing sludge at the bottom of the sedimentation tank (with a moisture content of approximately 80%-90%) is transported to a plate-and-frame filter press via a sludge pump for dewatering, forming sludge cakes with a moisture content of ≤ 60%. These sludge cakes must be managed as hazardous waste and sent to qualified institutions for solidification/stabilization treatment or cobalt recovery (e.g., through pyrometallurgical smelting or hydrometallurgical leaching). Clarified Liquid Treatment The upper clarified liquid needs to be tested for pH, chemical oxygen demand (COD, caused by residual citric acid), and heavy metal concentrations (e.g., Co, As, Cu). If it meets the standards (e.g., cobalt concentration < 0.01 mg/L, in line with the Environmental Quality Standards for Surface Water (GB 3838-2002)), it can be directly discharged. If it fails to meet the standards, further advanced treatment using ion exchange resins or membrane separation technology is required to ensure the complete removal of pollutants.