# Main Techniques to Reduce Concentrate and Achieve Salt–Organic Separation During Landfill Leachate Treatment Using Low-Rejection Nanofiltration Membranes

## TL;DR

This paper explores using low-pressure nanofiltration membranes to efficiently separate salt and organic matter in landfill leachate, reducing energy and concentrate volume.

## Contribution

The study introduces low-rejection nanofiltration as a novel, energy-efficient alternative to reverse osmosis for landfill leachate treatment.

## Key findings

- Nanofiltration reduces concentrate volume to less than 3% of the initial leachate volume at low pressure.
- Energy consumption is reduced by at least three times compared to high-pressure reverse osmosis.
- Organic solutions can be reduced more effectively than saline solutions due to lower osmotic pressure.

## Abstract

Landfill is a source of environmental concern as it may contaminate surface and groundwater, which could be a major source of potable water supply. Reverse osmosis (RO) membrane treatment is a well-known technique for treating leachate, but it requires high pressures of 80 bars or more to function. In addition, pretreatment, scaling, biofouling and concentrate disposal bring additional challenges to RO operation. The use of nanofiltration (NF) membranes with low rejection ensures the concentrate is separated into organic and salt solutions at a low pressure of 16–18 bars and ensures the concentrate volume is reduced to less than 3% of its initial value. This results in a reduction in energy consumption by a factor of least three compared to using conventional high-pressure RO, which reduces the initial leachate amount to 9–10%, and evaporation results in a subsequent reduction in concentrate volume to 3–4 per cent of the initial leachate volume. Due to the low osmotic pressure, the volume of an organic solution after separation can be reduced by three to four times compared to a saline solution of the same concentration.