Removal of metals and nitrogen from mining wastewaters in treatment wetlands - Oulu

Removal of metals and nitrogen from mining wastewaters in treatment wetlands and via utilization of locally available biomass as sorbent materials.

Published: 23 May 2016

The use of treatment wetlands and bio-sorbents for the removal of metal and nitrogen from mining waters – University of Oulu

Treatment wetlands for metal and nitrogen removal

Background: Wetlands are generally well-suited for the purification or polishing of wastewaters as they retard the flow of water and provide a large filtration network with many adsorptive surfaces on soil particles and opportunity for uptake by plants and microorganisms. Good retention of toxic metals, suspended solid, phosphorous and nitrogen compounds are mostly reported.

Issue: seasonal variations can occur with decrease purification efficiency reported under cold climate conditions.

Objective and methods: The research proposed under the Min-North project aims to clarify the effect of cold climate (low temperatures and freeze and thaw cycles) on wetland retention processes via field measurements (e. g. water sampling and analysis, ground water level, ground frost level, nitrogen gas emissions, and snow cover) and pilot scale experiments.

Bio-sorbents for metal and nitrogen removal

Background: Sorption is considered an effective purification method for industrial wastewaters and is widely applied for the removal of several pollutants. Nevertheless, material costs, regeneration and disposal issues have propelled the search for low-cost biodegradable sorbents. Peat and sawdust are inexpensive, biodegradable and widely available sorbents which are mostly composed of lingocellulosic constituents.

Issue: Although several studies have reported substantial potential of natural or modified bio-based sorbents for mining water purification; there is a lack of pilot scale demonstration of research findings and possible application methodology. Furthermore, the influence of cold temperatures in sorption rates and capacity and the possibilities of material recovery have not been fully evaluated.

Objectives and methods: The research work aims to address the clear gap which exists between the evaluation/development of bio-based sorbents and their application. The suitability of biosorbents (peat and sawdust) for the purification of mining wastewater will be evaluated based on laboratory experiments and pilot tests.

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