5 Hydrolysis (Acidogenesis) -Oxic Process

2H 2
G 5 .2
Methanogenesis is more efficient than Hydrolysis High hydrogen pressure reduces degradation rate.
Primary Sludge Hydrolysis – A Case Study
25
Conversion efficiency (%)
Raw sludge 20 15 10 5 0 0 1 2 3 4 5 6 7 Smashed sludge
HRT (d)
CH 3 CI H 2 CH
4
H

CI

G 163 . 4 kJ / Mol
High hydrogen pressure stimulates high reduction rate. Hydrolysis is more efficient than methanogenesis
70 60 50 40 30 20 10 0 0 0.04 0.05 0.065 0.105 0.3 0.4 0.9
Row sludge disintegrated sludge
Fraction (%)
Particle size (mm)
Hydrolysis conversion rates with row sludge and disintegrated sludge
Other chlorinated organics
• Chlorinated phenol • Chlorinated benzoic acid • Dichlorinated benzoic acid
Hydrolysis of biologically recalcitrant substances-Cont
Philosophy in WWTP
Waste water
Water Train
Primary sludge Wasted sludge
Purified water
Sludge disposal
Sludge Train
Primary sludge：Energy contained
Biogas
Philosophy in WWTP
Hydrolysis (Acidogenesis) -Oxic Process
Process History
Effluent from anaerobic digester usually contains high COD and can’t meet the requirement of discharging standards.
Waste water Primary sludge Purified water
Water Train Hydrosate Wasted sludge Anaerobic Hydrolysis digestion
Biogas
Primary sludge
Hydrolysis reactor
Hydrosate
• • • • VSS VFA pH OUR
How to change a process from anaerobic to aerobic
• Dilution rate (HyHydrolysis Kinetics
Hydrolysis products Hydrolysis Particulate substances Sp Sr Substrate utilization And growth Biomass X

r
Three processes are always coupled together

qm Sr ks Sr
• Biomass growth kinetics
dX dt 1 dS Y dt
r
Hydrolysis reactor
• Activated sludge (Contactor, UASB,…) • Biofilm is not considered as an efficient process, especially for particulate substrate
Contactor process
• Process composition
Contactor Clarifier
Hydrolysis of biologically recalcitrant substances
• Chlorinated organic substances are reduced to methane and chloride
Enzyme metabolic
Processes involved: Hydrolysis Substrate utilization Biomass growth
Hydrolysis Kinetics
• Hydrolysis kinetics
dS dt
1 dS X dt
p
khS
p
• Substrate utilization kinetics
甲苯
C 6 H 5 CH
3
9 H 2 O 3 CH 3 COOH
H 2 CO
3
6H 2
G 165 . 7
苯甲酸
C 6 H 5 COOH
7 H 2 O 3 CH 3 COOH
H 2 CO
3
3H 2
G 165 . 7
苯酚
C 6 H 5 OH 5 H 2 O 3 CH 3 COOH
Chemical Thermo Biological
Effects of temperature on the conversion rate under different HRTs
14
Conversion efficiency (%)
12 10 8 6 4 2 0 15 20 25 30 35 HRT=1d HRT=2d HRT=3d
Roadmap of Hydrolysis
Hydrolysis products
Hydrolysis
Polymer or particulate substances
Substrate utilization and growth
Biomass Enzyme metabolic
Difference between hydrolysis and anaerobic digestion
• • • • Temperature ORP pH ……
Factors affecting hydrolysis process
• • • • Substrate Particle size Environment (T, ORP, pH) Sludge morphology
Process evaluation
INTRODUCTION
• Traditionally, primary sludge is digested with wasted activated sludge from the biological treatment to produce biogas. • Recently, an innovative way was developed to hydrolyze the primary sludge to produce external carbon sources for nutrient removal in water train in WWTP.
– Anaerobic-aerobic process – Hydrolysis-oxic process
Concept
• Definition: The biochemical process taking place outside cells • Enzyme mediate process • A general process which can be carried out in anaerobic, anoxic and aerobic conditions • Concurrence (Hydrolysis and Acidogenesis or other biological processes) • Hydrolysis is not a independent unit, which means that the process is always coupled with other processes
T (¡ ) æ
Effects of solid fraction in the sludge on the conversion rate
18
Conversion efficiency (%)
16 14 12 10 8 6 0 1 2 3 4 5 6 7
Solid fraction (%)
Particle size distribution in the row sludge and disintegrated sludge