The Walnut Shell Filter is a specialized industrial media filtration system engineered exclusively for high-efficiency removal of free oil, dispersed oil, suspended solids, silt, and mechanical impurities from oily water sources — a targeted solution that solves the core limitations of traditional quartz sand filters (poor oil removal performance, easy clogging and hardening in oily environments). Using specially treated refined walnut shell as the core filtration medium, this filter leverages the medium’s porous structure, high hardness, and unique hydrophilic oleophobic properties to adsorb and intercept oil contaminants and solid particles, delivering stable, low-oil-content, low-turbidity filtered water for oily water treatment scenarios.
Available in fully automatic and manual operation versions, this filter features a rugged pressure tank made of corrosion-resistant materials, built to withstand long-term use in harsh oily and industrial environments. Automatic models are equipped with an intelligent control system that activates backwashing and medium regeneration via preset pressure differential or timer, with a unique stirring and friction backwashing design to thoroughly detach oil and impurities from the walnut shell medium; manual models rely on simple valve operation for small-scale or low-demand oily water treatment. Suitable for 24/7 continuous operation, it effectively protects downstream equipment such as RO membranes, ultrafiltration modules, heat exchangers, and pipelines from oil contamination and clogging, and supports single or parallel multi-unit installation to meet large-flow oily water treatment demands.
Core Technical Features
This walnut shell filter follows global industrial water treatment standards, with standardized specifications and customizable configurations to adapt to diverse oily water working conditions. Core technical parameters and functional details are clearly listed in the table below for quick reference:
Technical Feature | Specification & Design Details | Core Operational Function |
|---|
Filtration Medium | Specially polished & chemically treated walnut shell, particle size 0.8–2.0mm; high hardness, wear-resistant, hydrophilic oleophobic, porous structure | Efficiently adsorbs free/dispersed oil, intercepts suspended solids; strong regeneration capacity, not easy to harden or bond in oily water |
Filtration Performance | Oil removal efficiency ≥90% for free oil; suspended solids removal accuracy 5–50μm; effluent oil content ≤5mg/L, turbidity ≤3NTU | Meets strict oily water treatment standards for industrial and oilfield scenarios, effectively eliminates oil contamination risks |
Tank Material | Carbon steel with rubber lining, SS304, SS316L, FRP; anti-oil corrosion, anti-wear inner wall treatment | Resists oil erosion and chemical corrosion, adapts to neutral and weakly alkaline oily water, long service life |
Operating Parameters | Design pressure 0.15–1.0MPa; working temperature 0–65°C; filtration flow rate 10–800m³/h (customizable) | Stable operation under conventional industrial oily water pressure and temperature, scalable flow for small to large projects |
Backwashing & Regeneration System | Water backwash + mechanical stirring friction backwash; automatic/timer/pressure differential control; backwash duration 4–6 minutes | Thoroughly detaches oil and impurities from walnut shell medium, restores filtration capacity completely; low backwash water consumption (2–4% of total filtered flow) |
Control Mode | Fully automatic (digital control panel, fault alarm, oil content monitoring interface) / manual ball valve operation; optional remote control | Automatic models require almost no manual supervision; manual models offer simple operation for small-scale sites |
Key Product Advantages
Industry-Leading Oily Water Treatment Performance: Unlike ordinary media filters, the specially treated walnut shell medium has strong oil adsorption capacity and unique hydrophilic oleophobic properties, making it highly effective at removing free and dispersed oil that quartz sand filters cannot handle. It avoids oil-induced clogging and hardening, maintaining stable filtration efficiency even in high-oil-content water sources.
Ultra-Long Filter Medium Service Life & Low Consumable Cost: Walnut shell medium features high hardness and wear resistance, with a service life of 3–5 years under normal working conditions. Only 10% annual topping up is needed instead of full replacement, drastically cutting consumable costs compared to disposable filter cartridges and frequent replacement of quartz sand. This makes it the most cost-effective choice for long-term oily water treatment.
Strong Regeneration Capacity & Uninterrupted Operation: The unique mechanical stirring and water backwashing combined system thoroughly cleans oil and impurities attached to the walnut shell, completely restoring filtration performance without manual scrubbing. Automatic models run independently with timed or differential pressure backwashing, supporting 24/7 continuous operation and eliminating production downtime from filter maintenance.
Wide Adaptability to Oily Water Scenarios: Compatible with various oily water sources, including oilfield produced water, petrochemical circulating water, mechanical processing cutting fluid, steel rolling wastewater, and port oily sewage. It adapts to fluctuating oil content and suspended solid concentrations, with no strict pre-treatment requirements for influent water.
Compact Structure & Flexible Installation: Vertical pressure tank design saves installation space, with simple flange or threaded pipeline connections. It supports floor-mounted installation and parallel multi-unit combination for large-flow projects, with no complex auxiliary equipment required, reducing installation and commissioning time and costs.
Effective Protection for Downstream Water Treatment Equipment: As a front-end pretreatment device for oily water systems, it removes oil and solid impurities that cause scaling, clogging, and corrosion to downstream membrane modules, heat exchangers, and precision valves, extending the service life of core equipment and reducing later-stage maintenance and replacement costs.
Eco-Friendly & Energy-Saving: Walnut shell is a natural, degradable, non-toxic filtration medium with no secondary pollution. The backwashing system consumes minimal water and energy, aligning with global industrial environmental protection and energy conservation standards for oily water treatment.
Application Areas
The Walnut Shell Filter is the preferred specialized filtration equipment for oily water treatment worldwide, widely used in industries with oily wastewater and circulating water demands, covering core scenarios such as oilfield, petrochemical, mechanical processing, and metallurgy. Key application fields include:
Oilfield Industry: Oilfield produced water filtration, oilfield drilling wastewater treatment, oilfield circulating water purification, reinjection water pretreatment for oilfields
Petrochemical & Chemical Industry: Refinery oily circulating water filtration, chemical plant oily wastewater pretreatment, lubricating oil-containing process water purification, oil storage area rainwater sewage treatment
Mechanical Processing & Manufacturing: Metal cutting fluid filtration, mechanical processing oily wastewater treatment, equipment cooling oily circulating water purification
Metallurgical & Steel Industry: Steel rolling oily wastewater filtration, cold rolling mill circulating water treatment, metallurgical processing oily sewage purification
Port & Maritime Industry: Port terminal oily sewage treatment, ship oily wastewater pretreatment, wharf circulating water filtration
Food & Catering Industry: Food processing oily wastewater filtration, edible oil processing plant sewage pretreatment, catering oily water purification
Industrial Circulating Water System: Oily industrial circulating water purification, power plant oily cooling water filtration, factory circulating water reuse pretreatment
Frequently Asked Questions (FAQ)
1. How often does the walnut shell filter medium need to be replaced?
Under normal oily water treatment conditions, high-quality treated walnut shell medium has a service life of 3–5 years. Full replacement is only required when the medium is severely worn or contaminated; routine maintenance only requires 10% annual topping up of lost medium. Replacement frequency varies slightly with influent oil content: high-oil-content water sources may need partial supplementary replacement every 2–3 years, which is far more cost-effective than quartz sand and cartridge filters.
2. Can this filter handle emulsified oil, or only free oil?
This walnut shell filter is specially designed for high-efficiency removal of free oil and dispersed oil, with a removal rate of over 90% for these two types of oil. For emulsified oil, it can achieve preliminary separation and reduction; for high-concentration emulsified oil water, we recommend adding a small dose of demulsifier before filtration for better results, and we can provide targeted configuration adjustments for emulsified oil scenarios.
3. Will backwashing affect the normal operation of oily water treatment?
Single-unit automatic filters will pause filtration for 4–6 minutes during backwashing, which is a short interruption and rarely affects continuous oily water treatment. For projects requiring 24/7 uninterrupted operation (such as oilfield reinjection water), dual parallel installation is recommended: one unit filters while the other completes backwashing and regeneration, ensuring zero downtime and stable effluent quality.
4. What water quality conditions is this filter NOT suitable for?
This filter is suitable for neutral and weakly alkaline oily water (pH 6–9). It is not recommended for strongly acidic water (pH <4), water with a large amount of viscous organic matter, or high-concentration corrosive chemical water, as these will damage the walnut shell medium and reduce oil removal efficiency. For special water quality, we can customize composite medium configurations to adapt to complex working conditions.
5. Is professional installation and daily maintenance required for this filter?
No professional installation team is needed — we provide a complete installation manual, pipeline connection diagram, and operation guide, allowing on-site technicians to complete installation and commissioning within a short time. Daily maintenance is extremely simple: automatic models only require regular inspection of the control panel and backwashing system; manual models need regular valve checks and periodic backwashing. There are no complex operational steps, and dedicated full-time operators are not required.
Activated Carbon Filter
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