Leachate treatment

Leachate characteristics and treatment difficulties

Formation mechanism:

Rainwater infiltration (accounting for ≥70%) and waste biochemical reaction liquid

Typical pollutant concentrations:

COD: 5,000-60,000 mg/L

NH₃-N: 500-3,000 mg/L

Heavy metals: Zn/Cr/Pb total 10-50 mg/L

Environmental risks:

1 mg of leachate can pollute 1 m³ of groundwater (according to the Class III limit of the Groundwater Quality Standard)

Core treatment process combination

1. Pretreatment system

Media filter: remove ≥50μm suspended solids (filtration rate 8-10m/h)

Ultrafiltration (UF) unit:

Molecular weight cutoff: 100 kDa

Flux maintenance: 15-25 LMH (transmembrane pressure difference ≤0.3MPa)

2. Deep treatment link

"MBR+RO" double membrane process:

MBR sludge concentration: 12-18g/L (SRT＞50 days)

RO desalination rate: ＞98% (rolled polyamide membrane, pressure 4.0-6.0MPa)

Evaporation crystallization backup:

Applicable to RO concentrated water (TDS＞50,000mg/L), steam consumption 0.8-1.2t/t water

3. Deep removal guarantee

Ozone catalytic oxidation:

O₃ dosage 80-120mg/L, CT value＞15 mg·min/L

Activated carbon adsorption:

Iodine value ≥900mg/g, carbon bed space velocity 2-4 BV/h

Project case of a provincial capital landfill

Processing scale: 800 tons/day

Raw water quality:

COD=38,500mg/L, NH₃-N=2,150mg/L

Process flow:

Regulating tank→anaerobic UASB→MBR→RO→ozone activated carbon

Operation effect:

COD reduced to <100mg/L (removal rate 99.7%)

NH₃-N reduced to <8mg/L

Cost of water treatment per ton: ￥35-42 (including depreciation)

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