Humic Substance Extraction from Landfill Leachate
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Solution Overview
Problem
Existing processes for treating sanitary landfill leachate do not effectively extract and purify humic substances, which are valuable for agriculture due to their soil conditioning and nutrient facilitation properties, despite their high concentration in landfill slurry.
Innovation Solution
A four-step process involving physical-chemical coagulation and flocculation, filtration through sand, microfiltration, and nanofiltration, followed by reverse osmosis and catalytic oxidation to concentrate humic substances and treat the effluent for reuse, utilizing FeCl3, anionic and cationic polymers, and ionic exchange resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing treatment processes are used for sanitary landfill leachate, then the treatment can be performed with simple equipment, but humic substances cannot be effectively extracted and purified
Solution Approach 1:
The treatment process is divided into multiple sequential stages: coagulation-flocculation, sand filtration, microfiltration, nanofiltration, and reverse osmosis. Each stage targets specific contaminants and progressively concentrates humic substances, transforming a single complex extraction task into manageable sequential steps that achieve high purification precision.
Solution Approach 2:
The patent employs nested filtration systems where microfiltration membranes are combined with nanofiltration membranes, which are in turn combined with reverse osmosis membranes. This nested structure allows each filtration stage to build upon the previous one, with progressively smaller pore sizes and higher rejection rates, enabling effective humic substance extraction while organizing complex equipment in a hierarchical manner.
2Quantity of substance
If physical-chemical coagulation and flocculation is used to extract humic substances, then the concentration of humic substances increases, but the effluent requires further treatment to meet environmental regulations
Solution Approach 1:
The coagulation-flocculation process selectively extracts and concentrates humic substances from the leachate by forming removable flocs. This separation allows the humic-rich concentrate to be harvested for agricultural use while the treated effluent proceeds to additional treatment stages to remove remaining contaminants before discharge or reuse.
Solution Approach 2:
Coagulants and flocculants act as intermediary substances that bridge the gap between dissolved humic substances and removable particulate matter. These chemicals facilitate the aggregation of humic substances into flocs that can be easily separated, while subsequent treatment stages use additional intermediaries to address remaining effluent quality issues.
3Object-affected harmful factors
If multiple filtration stages are implemented to purify effluent, then the effluent quality improves to meet regulations, but the process time and operational complexity increase
Solution Approach 1:
Coagulation and flocculation are performed as preliminary treatment stages to remove the bulk of suspended solids and concentrate humic substances before the effluent enters the filtration system. This preliminary action reduces the contaminant load entering subsequent filtration stages, allowing them to operate more efficiently and reduce overall process time while maintaining high effluent quality.
Solution Approach 2:
The patent employs a series of filtration stages with progressively changing parameters - pore size decreases from microfiltration to nanofiltration to reverse osmosis, while pressure and rejection rates increase. This systematic parameter progression optimizes the balance between purification efficiency and process speed, with each stage tuned to remove specific contaminant size ranges.
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 process efficiently extracts and purifies humic substances, producing a concentrated product for agricultural use and treated water that complies with environmental regulations, overcoming the limitations of previous methods.
Implementation Method 1
physical-chemical coagulation and flocculation
Implementation Method 2
physical-chemical coagulation and flocculation
Implementation Method 3
filtration through sand, microfiltration, and nanofiltration
Implementation Method 4
reverse osmosis
Implementation Method 5
catalytic oxidation
Implementation Method 6
ozone generator
Implementation Method 7
aeration tank
Implementation Method 8
continuous current source maintains the electric potential difference between 4 volts and 6 volts in the electrodes
Implementation Method 9
ionic exchange resins
Data Source
Figure 1~4
AI summary
Patent of invention for process of extracting and purifying humic substances from sanitary landfill leachate comprising four steps: 1st physical-chemical step with the withdrawal of inert solids, 2nd step of filtration, 3rd step of purification of the humic substances with ionic exchange column followed by reverse osmosis and 4th step of catalytic oxidation and ammonolysis by cathodic reduction, obtaining treated effluents that complies with environmental legislation in terms of disposal or re-use of water.