Microcosm Testing of Municipal Sewage and Green Waste for Full-Scale Remediation of an Acid Coal Pit Lake, in Semi-Arid Tropical Australia

Abstract

Pit lakes (abandoned flooded mine pits) represent a potentially valuable water resource to mining companies, the environment and regional communities across arid inland Australia. However, the water is often of low pH with high dissolved metal concentrations.The addition of organic matter to the pit lakes to enhance microbial sulfate reduction is potentially a cost effective and sustainable remediation strategy for these acid waters. However, the cost and availability of sufficient quantities of suitable organic substrates is typically limiting in these remote regions. Nevertheless, small quantities of sewage and green waste (organic garden waste) are often available in these areas from the regional towns which support the mines. This paper reports on preliminary microcosm laboratory experiments in preparation for the treatment of an acid (pH 2.2) coal mine pit lake in semi-arid tropical, inland north Queensland, Australia with municipal treated sewage and green waste.A laboratory experiment using microcosms (acrylic tubes) containing acid pit lake water and sediment were treated as follows; controls (untreated), sewage, green waste and sewage and green waste. The pH increased to a maximum of 5.5 in 145 days in the green waste and sewage treatment, with notable decreases of iron, aluminium and toxic heavy metals. Our results indicated that the green waste was a key component in alkalinity production and heavy metal removal.

COVID-19 Face Masks as a Long-Term Source of Microplastics in Recycled Urban Green Waste

“…While household waste separation into recyclable hard waste (i.e., paper, aluminum, plastics) and solid waste destined for landfill is standard procedure among most local government councils, some councils deploy separate bins for the collection of green waste/organic waste (e.g., food remains, garden waste, lawn clippings), in addition to green waste collection from industry, such as landscaping businesses [45,46]. At the waste management center, the green waste is shredded or ground and composted for a set period [47], after which it is sold as garden mulch or as 'manufactured soil' [48,49], which is widely and frequently used in land reclamation and remediation projects [50][51][52].…”

Effective passive treatment of high-strength acid mine drainage and raw municipal wastewater in Potosí, Bolivia using simple mutual incubations and limestone

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In-Situ Coal Pit Lake Treatment of Acidity When Sulfate Concentrations Are Low

“…In February 2004 we added a further dose of superphosphate to the P treatments and 32.6 g of urea fertilizer (CO(NH 2 ) 2 ; 46% N) to all treatments to increase N concentrations by 20-30 µg L -1 in response to this. The utilization of available N by decomposition processes was one of the reasons that McCullough et al (2006) chose to utilize both mulch (green waste) and sewage in combination to remediate a mine pit lake. The sewage was included to provide a source of nutrients particularly N to feed the decomposition process.…”