Upflow Reactor Softening for Hardness and TOC Removal
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Solution Overview
Problem
Existing water treatment processes are inefficient in removing hardness and total organic carbon (TOC) from drinking water, especially when TOC concentrations exceed 3 mg/L, leading to the formation of undesirable disinfection by-products like trihalomethanes and haloacetic acid, and result in higher energy consumption and operational challenges.
Innovation Solution
An enhanced coagulation process combined with a softening process in an upflow reactor, using fine sand or calcium carbonate particles and a hardness reducing reagent like sodium hydroxide or lime, along with a coagulant like alum, to precipitate and agglomerate hardness and TOC compounds, respectively, followed by filtration to remove these contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical additives (detergents, sequestering agents, regenerating agents) are used to remove hardness, then hardness removal efficiency is improved, but energy consumption increases and process efficiency decreases over time
Solution Approach 1:
The patent extracts and removes hardness compounds (calcium and magnesium ions) from the water through precipitation and filtration processes, separating them from the treated water stream. This direct extraction approach replaces the need for continuous chemical additives and reduces energy consumption associated with heating and chemical dosing.
Solution Approach 2:
The system uses self-fluidizing particles (sand or calcium carbonate) that automatically provide surface area for hardness compound attachment without requiring external chemical additives. The particles self-regenerate through filtration and can be reused, eliminating the need for continuous chemical input and reducing operational energy consumption.
2Reliability
If conventional softening process is used, then hardness is removed, but TOC reduction is limited (only 5-10% when initial TOC is less than 3 mg/L)
Solution Approach 1:
The patent merges the softening process with an enhanced coagulation process in a single integrated system. The coagulation step adds alum or other coagulants that form floc with TOC, while the softening step removes hardness compounds. This combination achieves both hardness removal and significant TOC reduction (up to 51%) simultaneously, overcoming the limitation of conventional softening that only achieves 5-10% TOC reduction.
Solution Approach 2:
The coagulant is injected into the influent water before it enters the softening reactor, performing preliminary coagulation of TOC into floc. This preliminary action ensures that TOC is partially removed and aggregated before the water undergoes softening, allowing the subsequent filtration to efficiently remove both TOC and hardness compounds.
3Device complexity
If TOC is not reduced during water treatment, then treatment simplicity is maintained, but disinfection by-products (trihalomethanes, haloacetic acid) form when chlorine is added
Solution Approach 1:
The coagulation step performs preliminary removal of TOC before the water undergoes disinfection with chlorine. By injecting coagulant and forming floc with TOC in advance, the system reduces the amount of organic matter available to react with chlorine, thereby minimizing the formation of harmful disinfection by-products like trihalomethanes and haloacetic acid.
Solution Approach 2:
The patent converts the potentially harmful interaction between TOC and chlorine into a beneficial process by using coagulation to aggregate TOC into removable floc before disinfection. This transforms the problem of TOC-chlorine reactions into a controlled process where TOC is removed through coagulation-filtration, and only minimal residual TOC remains to react with chlorine, significantly reducing harmful by-product formation.
4Quantity of substance
If coagulant is injected into influent upstream of softening reactor, then TOC reduction is enhanced, but additional chemical handling and mixing requirements are introduced
Solution Approach 1:
The patent merges the coagulation and softening processes into a single integrated reactor system. The coagulant is injected upstream, and both coagulation floc formation and hardness precipitation occur within the same reactor before filtration. This merging reduces the number of separate treatment stages, chemical handling points, and mixing requirements compared to having separate coagulation and softening systems.
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
The process effectively reduces TOC concentrations by up to 51% and enhances hardness removal, while reducing the need for pH adjustment reagents, lowering operational costs and improving the efficiency of water treatment, especially for influents with high TOC levels.
Implementation Method 1
The coagulant mixes with the influent and as the influent water flows upwardly through the fluidized bed of particles and through the reactor, coagulation occurs. That is, the constituent of total organic carbon, including both soluble and insoluble species, are attracted and agglomerated into the particles that form floc.
Implementation Method 2
A hardness reducing reagent, such as sodium hydroxide or lime, is injected into the bottom portion of the reactor and mixed with the water. This has the effect of raising the pH of water which decreases the solubility of hardness compounds. This results in the hardness compounds precipitating from the water
Implementation Method 3
The reactor is provided with particles of fine sand or calcium carbonate which provide surface area onto which precipitated hardness compounds, such as calcium carbonate, attached.
Implementation Method 4
The water is discharged from the reactor and directed through a filtration process where the floc of organic material is captured and removed from the water.
Data Source
AI summary
The present invention relates to a process for reducing hardness and organic matter concentrations in water. The water being treated is directed into and through an upflow reactor containing a media. As the water moves up the reactor, the media is fluidized. At least one softening reagent is added to the water in the reactor, resulting in an increase in pH and the precipitation of hardness. The precipitated hardness compounds are attached on the media. To enhance the reduction of organic matter in the water, a coagulant is mixed with the water upstream of the softening reactor. As the water flows upwardly through the reactor, the coagulant reacts with organic particles in the water, causing the organic particles to bind and form floc. Downstream of the reactor, the water is subjected to a filtration process that removes the floc containing the organic matter.