Wastewater Oxygenation via Surface Return Pumping
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Solution Overview
Problem
Existing methods for reducing hydrogen sulphide in wastewater tanks are complex, costly, and require expensive equipment, with high maintenance needs, and often fail to prevent high hydrogen sulphide levels from being pumped out during drainage.
Innovation Solution
A method and device that divert a flow from the tank, oxygenate it with ambient air, and return it above the liquid level, using a conventional pump and ejector system, with control based on hydrogen sulphide measurements to maintain safe levels, avoiding the need for high-pressure oxygen supply and additional equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If gaseous chlorine is added to inhibit bacterial activity, then hydrogen sulphide formation is reduced, but the wastewater becomes poisonous and strongly corrosive
Solution Approach 1:
The patent converts the harmful effect of anaerobic bacteria producing hydrogen sulphide into a beneficial process by introducing oxygen to create aerobic conditions. This eliminates the need for toxic additives like chlorine while solving the hydrogen sulphide problem through natural biological processes.
Solution Approach 2:
The patent uses oxygen as an intermediary substance to mediate between the wastewater and the harmful bacterial processes. By introducing oxygen, it creates a chemical environment that prevents hydrogen sulphide formation without requiring direct contact with toxic substances.
2Object-generated harmful factors
If Nutriox® and calcium nitrate are used to inhibit bacterial activity, then hydrogen sulphide formation is reduced, but operating costs increase due to expensive additives
Solution Approach 1:
The patent employs self-service by utilizing the wastewater's own properties and natural biological processes. The system uses the wastewater's flow and existing microbial community, enhanced by oxygen introduction, to eliminate hydrogen sulphide without requiring external expensive additives.
Solution Approach 2:
The patent changes the chemical parameters of the wastewater by introducing oxygen, which fundamentally alters the biological processes occurring in the tank. This parameter change (oxygen concentration) enables the system to eliminate hydrogen sulphide through aerobic respiration rather than requiring chemical additives.
3Object-generated harmful factors
If air is supplied to refresh the wastewater, then hydrogen sulphide levels are reduced, but the system becomes complex requiring high-pressure oxygen supply and additional equipment
Solution Approach 1:
The patent segments the wastewater flow into multiple streams that are circulated through the tank. This segmentation allows oxygen to be introduced at multiple points and ensures thorough mixing and oxygenation without requiring high-pressure systems or complex equipment.
Solution Approach 2:
The patent employs periodic action by circulating wastewater through the tank in cycles. The pump operates periodically to move water through the oxygenation zone and back, creating continuous oxygenation effects without requiring continuous high-pressure oxygen supply.
4Device complexity
If oxygenation is provided by pumping back water using ordinary sewage pumps, then equipment costs are reduced, but the oxygenated water may be returned to the pump well or sewer system at inappropriate times
Solution Approach 1:
The patent implements feedback control by using sensors to detect hydrogen sulphide levels and tank conditions. This feedback information is used to automatically control the pump operation, ensuring oxygenation occurs only when needed and preventing premature or inappropriate return of oxygenated water to the pump well or sewer system.
Solution Approach 2:
The patent introduces dynamics by making the pump operation adaptive rather than static. The pump runs or stops based on real-time conditions in the tank, such as hydrogen sulphide levels and water flow, allowing the system to respond dynamically to changing conditions and optimize both equipment use and treatment effectiveness.
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 approach reduces hydrogen sulphide levels effectively, lowers operational costs, and ensures that wastewater with high hydrogen sulphide is not discharged, providing reliable and efficient oxygenation with reduced energy consumption and equipment wear.
Implementation Method 1
oxygenating said flow by contact with an oxygen-containing gas
Implementation Method 2
The gas is supplied to the wastewater through an ejector, which means that, as the wastewater passes through said ejector at high velocity, gas containing oxygen enters through an air inlet of the ejector and mixes with the wastewater
Data Source
Figure 1
AI summary
A method and device for reducing the amount of hydrogen sulphide in wastewater in a tank (1), in which a flow is diverted from said tank, and the flow is oxygenated by contact with an oxygen-containing gas. The flow is then returned to the tank (1) above a liquid level in the tank (1). Since the flow is returned above the surface, the flow can be driven by a conventional sewage pump, which is considerably cheaper than the compressors normally required to return oxygenated water below the surface. It has also been found that a better oxygenating effect is provided if the flow is returned to the tank above the surface, resulting in an increased reduction of hydrogen sulphide. The diversion of a flow from the tank is controlled based on the measurements of hydrogen sulphide amount in the tank. Due to introducing a measuring means and control unit connected with a sewage pump, the oxygenation takes place only when necessary, which optimizes the process.