Anoxic Membrane Filtration System for Selenium Removal
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Solution Overview
Problem
Current water treatment systems for removing dissolved contaminants, such as selenium, are inefficient, costly, and prone to re-dissolution of contaminants due to uncontrolled oxidation-reduction potential (ORP) fluctuations.
Innovation Solution
A system comprising a bioreactor and a membrane filtration system operating in an anoxic mode, with a fluid recirculator and oxidant supply to control the ORP within a predetermined range, inhibiting film buildup on the membrane and maintaining the water in a depleted oxygen state to prevent re-dissolution of contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If membrane filtration is used to remove dissolved contaminants, then filtration efficiency is improved, but film buildup on the membrane occurs reducing performance
Solution Approach 1:
The system employs periodic backwashing cycles where flow direction through the membrane is reversed to dislodge and remove accumulated film and contaminants from the membrane surface, restoring filtration efficiency without permanent membrane damage
Solution Approach 2:
The membrane filtration system incorporates automatic self-cleaning mechanisms through integrated backwashing and chemical cleaning cycles that maintain membrane performance without requiring manual intervention, enabling the system to service itself and prevent film buildup accumulation
2Productivity
If oxidant is introduced to control ORP, then contaminant removal effectiveness is improved, but re-dissolution of contaminants may occur
Solution Approach 1:
The system incorporates ORP sensors and control systems that continuously monitor oxidation-reduction potential and automatically adjust oxidant dosing rates to maintain optimal ORP ranges, preventing both insufficient contaminant removal and excessive oxidant addition that could cause re-dissolution
Solution Approach 2:
The system dynamically adjusts oxidant dosage based on measured ORP values, contaminant concentrations, and flow rates, optimizing the chemical environment to maintain contaminants in precipitated form while preventing re-dissolution through controlled oxidation levels
3Ease of manufacture
If system size is reduced to lower cost, then treatment efficiency per unit cost is improved, but system reliability may be compromised
Solution Approach 1:
The system integrates multiple functions into single components: the membrane module performs both filtration and contaminant concentration, the backwashing system serves both cleaning and flux recovery functions, and the control system manages ORP, flow rates, and cleaning cycles simultaneously, reducing overall system size while maintaining reliability
Solution Approach 2:
The system recycles permeate water back to the inlet for re-treatment, recovering valuable water and maintaining high removal efficiency without requiring larger processing capacity, while concentrated contaminant streams are periodically discharged to prevent buildup
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
Effectively removes dissolved contaminants like selenium by maintaining a controlled ORP, reducing the size and cost of treatment systems, and preventing re-solublization of treated contaminants, thereby enhancing filtration efficiency and safety.
Implementation Method 1
a membrane associated with the vessel and positioned to extract permeate from the received water
Implementation Method 2
an oxidant supply positioned to introduce an oxidant into the vessel, the oxidant supply being adjustable to control the oxidation-reduction potential of the received water in the vessel within a predetermined range
Implementation Method 3
a fluid outlet positioned to direct fluid toward the membrane to inhibit film build up on the membrane
Implementation Method 4
a fluid recirculator positioned to recirculate fluid between the vessel and the fluid outlet
Data Source
AI summary
A system is provided for treating contaminated water. The system includes a bioreactor having an outlet for treated water and a filter coupled to receive treated water from the outlet of the bioreactor. The filter is configured to operate in an anoxic mode. The filter has: (a) a vessel configured to receive the treated water, (b) a membrane associated with the vessel and positioned to extract permeate from the received water, (c) a fluid outlet positioned to direct fluid toward the membrane to inhibit film build up on the membrane, (d) a fluid recirculator positioned to recirculate fluid between the vessel and the fluid outlet, and (e) an oxidant supply positioned to introduce an oxidant into the vessel, the oxidant supply being adjustable to control the oxidation-reduction potential of the received water in the vessel within a predetermined range.