Nitrogen removal from sediment dredging

Facts & Figures

Location: Kishon River, Israel

Wastewater Source: River sediments

Daily Flow Rate: 7,000 m³/day

Salinity (TDS): ~20,000 mg/l (~2%)

Nitrogen Load: 650 kg/day

Effluent Discharge Destination: Kishon River

Contract type: Turn-key + O&M

Completion Date: 2013

Following the remediation efforts of the polluted Kishon River, sediments from the bottom of the river are dredged and discharged to an onshore treatment plant. The sediments, accumulated over the past 30-40 years, are polluted with hydrocarbon residues from oil refining procedures and heavy metals from fertilizer industries. The final purified effluent is then discharged back to the river.

The treatment plant includes two main sections – The slurry dewatering section and the reject treatment plant.

In the dewatering section, specially designed decanters treat the incoming slurry, where the dewatered sludge is scattered and biologically treated in a nearby field.

7,000 m³/day of the reject from the dewatering units is discharged to the Liquid Process Plant (LPP) for nitrogen and TSS removal. The plant includes 12,000 m³ bio-reactor and a secondary clarifier. The bio-reactor comprises aerobic zone for nitrification followed by anoxic zone for De-nitrification. The final effluent overflows from the clarifier back to the river.

On-line analyzers were installed on the effluent discharged line as requested by the authorities to continually monitor its quality. Among these analyzers: Turbidity, Conductivity, ammonia, nitrate and TOC. Furthermore, lab measurements were taken on a daily basis.