Dual-Layer and Multi-Layer Media Filters: Technical Advantages in Oilfield Wastewater Treatment
China's demand for crude oil remains high. Secondary and tertiary oil recovery generate large volumes of oilfield produced water characterised by high oil concentration, high salinity, heavy suspended solids and complex chemical additives. After conventional treatment, key indicators such as suspended solids concentration and median particle size often fail to meet the strict fine-water-injection quality required by low-permeability and ultra-low-permeability oilfields. Discharging non-compliant water or reinjecting it ineffectively damages both the formation and the environment. As water scarcity worsens and environmental requirements tighten, using treated produced water as a source for fine water injection has become the inevitable direction for resource recovery in oilfields.
In oily wastewater treatment, filtration is usually the final polishing step. The main technical routes are interception with strongly hydrophobic and oleophilic materials, adsorption with high-surface-area porous oleophilic hydrophobic media, or oil-water separation through membranes with selective separation characteristics. Existing filtration technologies fall into three categories: surface filtration, deep-bed filtration and membrane filtration. Deep-bed filtration is currently the most widely used in advanced wastewater treatment and reuse because its process is simple and reliable.
Conventional single-layer graded media are easily affected by hydraulic classification during backwashing, so fine particles accumulate on the surface of the bed and cause clogging, faster head loss and shorter filtration cycles. When treating oily wastewater, media fouling and poor backwashing results are common. In addition, because the water passes through the fine media before the coarse media, the pollutant-holding capacity of the coarse layer is never fully used and the dirt-holding capacity of the whole bed is limited.
Because media characteristics strongly affect effluent quality and head loss, SINOKLE overcame the limits of conventional media by developing dual-layer and multi-layer composite filtration systems using quartz sand, anthracite, emery and other filter media. The units suit both clean water and wastewater sources and the media combination can be configured flexibly to match the water quality required. In operation, oily wastewater passes down through the bed and oil and suspended solids are effectively intercepted. The system is compact, fully equipped, stable in operation, easy to run, thoroughly backwashed and simple to maintain, and it is also suitable for advanced treatment of industrial wastewater in metallurgy, chemicals, textiles and other sectors.
Figure. Dual-layer and multi-layer media high-precision filter
Engineering practice has shown that SINOKLE's dual-layer and multi-layer media filters achieve high filtration precision: removal efficiency for suspended solids above 2 μm exceeds 98%, and when treating oily wastewater the oil content and suspended solids concentration in the effluent are both below 5 mg/L. A single unit handles 5-150 m³/h and can be arranged in series or in parallel. The equipment runs stably, is easy to maintain, is highly automated and supports remote control, making it a widely applicable industrial-grade wastewater filter.
In short, the unit is a general-purpose industrial filtration solution for advanced oily wastewater treatment, adaptable to a wide range of flow rates and site conditions.
