GAC Filter Bed with Surface Cleaning for Water Purification
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Solution Overview
Problem
Existing water purification systems for municipal and surface water are inadequate in simultaneously removing suspended solids, total nitrogen, nitrate, total phosphate, heavy metal compounds, and dissolved organic micro-pollutants under varying hydraulic loads while maintaining high effluent quality, and require frequent filter cleaning that disrupts the purification process.
Innovation Solution
An integrated system combining coagulation/flocculation, mechanical filtration using granular activated carbon (GAC) with biological treatment and adsorption, where GAC acts as a support for biomass, allowing for one-step removal of impurities through mechanical filtration, biological degradation, and physical adsorption, with a surface layer cleaning mechanism to prevent clogging and saturation, and thermal reactivation of GAC for regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional biological treatment and filtration systems are used, then water purification is achieved, but multiple separate treatment steps are required and filter cleaning frequently interrupts the process
Solution Approach 1:
The patent combines multiple treatment functions (mechanical filtration, biological degradation, and adsorption) into a single integrated filter bed system using granular activated carbon. The GAC serves simultaneously as mechanical filter medium, biomass support for biological treatment, and adsorbent for dissolved organics, eliminating the need for separate treatment units and reducing overall system complexity.
Solution Approach 2:
The granular activated carbon bed performs multiple functions concurrently: mechanical filtration of suspended solids, biological degradation of organic compounds and nitrate through attached biomass, and adsorption of dissolved organic micro-pollutants. This multi-functional approach consolidates what would traditionally require separate treatment steps into one universal system.
2Reliability
If filter bed is cleaned by removing and replacing the entire filter medium, then clogging and saturation are removed, but the purification process is interrupted and operational time is lost
Solution Approach 1:
The filter bed is segmented into a removable top layer (containing accumulated solids and saturated carbon) and a fixed base layer (providing structural support and active biomass). During cleaning, only the top layer needs to be removed and replaced, while the base layer remains in place and continues filtration, allowing the process to resume quickly without complete system shutdown.
Solution Approach 2:
The saturated top layer of granular activated carbon is discarded and replaced with fresh carbon, while the base layer is retained and reused. This selective replacement minimizes material waste and reduces cleaning time compared to replacing the entire filter bed, maintaining continuous operation with minimal interruption.
3Productivity
If high hydraulic loads are applied to achieve high productivity, then water treatment capacity increases, but effluent quality may deteriorate
Solution Approach 1:
The filter bed uses a composite structure combining granular activated carbon particles with attached biological biomass. This composite material provides simultaneous mechanical filtration, biological degradation, and adsorption capabilities, enabling the system to maintain high effluent quality even under varying hydraulic loads by engaging multiple removal mechanisms concurrently.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system achieves reliable and thorough purification of water, meeting stringent discharge criteria, with extended intervals between backwash operations and enabling reuse of the filtrate for industrial or boiler feed water applications, while maintaining operational continuity without interrupting the purification process.
Implementation Method 1
Coagulation/flocculation, followed by floc removal: Fe or Al salts are used as coagulant / flocculant. In this way suspended solids, ortho-phosphate and some of the heavy metals and organic micro pollutants are removed
Implementation Method 2
Coagulation/flocculation, followed by floc removal: Fe or Al salts are used as coagulant / flocculant
Implementation Method 3
Mechanical filtration: a commonly applied technique to remove suspended solids
Implementation Method 4
Biological treatment: in particular denitrification entails the biological reduction of nitrate into N2 gas
Implementation Method 5
Biological treatment: in particular denitrification entails the biological reduction of nitrate into N2 gas
Implementation Method 6
Adsorption on the surface of activated carbon: especially hydrophobic, dissolved organic impurities are effectively removed by physical adsorption onto activated carbon
Data Source
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AI summary
The invention is directed to a process for purifying pre-treated wastewater and surface water, which process comprises adding a flocculating agent and/or a carbon source to the said wastewater or surface water and subsequently feeding the wastewater or surface water to a biological filter, whereby the water is fed in downward flow through a filtration basin, having substantially only GAC as the filter medium, which filter is further provided with a system for removing a surface layer of the filter by suction.