Aerobic Granule Formation via Semi-Batch Feast-Famine Control
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Solution Overview
Problem
Conventional aerobic granule formation methods struggle with stabilizing the formation of aerobic granules when wastewater contains a large amount of slowly degradable organic matter, leading to difficulties in solid-liquid separation and treatment efficiency.
Innovation Solution
A semi-batch reaction tank process is employed, adjusting the duration of the biological treatment process to maintain a ratio of MLSS concentration to BOD load of readily degradable organic matter within the range of 0.05 to 0.25 kg-BOD/kg-MLSS/day, ensuring a balance between feast and famine states for stable granule formation, and incorporating a higher biologically treated water outlet to enhance granule settling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sludge concentration is increased to increase the treatment rate, then the treatment rate is improved, but solid-liquid separation becomes difficult due to bulking
Solution Approach 1:
The patent changes the physical form parameter of the sludge from floc to granule. Aerobic granules have a dense spherical structure with high settling velocity (5-10 m/h) compared to conventional floc, enabling high sludge concentration (1500-5000 mg/L) to be maintained without bulking problems, thus resolving the contradiction between treatment rate and solid-liquid separation
2Productivity
If anaerobic biological treatment is used to achieve high-rate treatment, then the treatment efficiency is improved, but the target types of wastewater are limited and temperature control is required
Solution Approach 1:
The patent changes the operational mode parameter from continuous to semi-batch. The semi-batch operation creates alternating feast-famine cycles that promote granule formation in aerobic conditions, achieving high-rate treatment (0.05 to 0.25 kg-BOD/kg-MLSS/day) with aerobic granules that have broader wastewater applicability and no temperature control requirements
3Stability of the object's composition
If conventional aerobic granule formation methods are used, then granules can be formed, but stable formation is difficult when slowly degradable organic matter is present
Solution Approach 1:
The patent applies periodic action through semi-batch operation with feast-famine cycles. During the feast period, readily degradable organic matter is rapidly consumed; during the famine period, slowly degradable organic matter is gradually degraded. This periodic pattern stabilizes granule formation by creating selective pressure for granule-forming bacteria while maintaining versatility in degrading both types of organic matter
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 method allows for stable and efficient formation of aerobic granules with improved settling properties, even with high slowly degradable organic matter, enhancing wastewater treatment capacity and quality.
Implementation Method 1
a biological treatment process of biologically treating organic matter in the wastewater with microbial sludge
Implementation Method 2
a settling process of allowing settling of the microbial sludge
Data Source
AI summary
The present disclosure is an aerobic granule forming method using a semibatch-type reaction tank (10) for forming aerobic granules, the aerobic granule forming method being characterized in that: the organic substance includes an easily decomposable organic substance and a slowly decomposable organic substance; and the time of the biological treatment process is adjusted so that the value obtained by multiplying the ratio of the MLSS concentration in the semibatch-type reaction tank (10) to the BOD loading volume of the easily decomposable organic substance in the semibatch-type reaction tank (10) by [time of the operating cycle/time of the biological treatment process] is in the range of 0.05-0.25 kg BOD/kg MLSS/day.