Ground water and surface water sources, such as dams, rivers, lakes and canals, serve as important sources of the world’s drinking water [1, 2]. Treated (urban) or untreated (rural) surface water can be used for drinking, irrigation for farmers, fishing, as well as hold aesthetic value as tourist attractions [2]. It thus becomes of great importance, that good water quality, i.e., the chemical, physical as well as biological characteristics, is attained, because it influences the health status of any ecosystem [1].
While natural water quality differs from one place to another, depending on, e.g., change in seasons, climate, geochemical settings and biochemical processes, anthropogenic activities add to the differences that ultimately change the water use potential [2, 3]. Such activities include mining, agriculture, as well as industry. According to Akpor and colleagues [4], raw and partially treated wastewater released from industry are one of the major point sources of surface water pollution. This is particularly common in developing countries. Wastewater contains harmful microorganisms, pharmaceuticals, personal care products, as well as heavy metals, [2, 5]. Wastewater treatment plants (WWTPs) that serve to recycle and release wastewater effluents with little effect on the surrounding ecosystem, tend to release effluent that is often inadvertently contaminated with toxic inorganic compounds, largely due to poor plant designs and inadequate wastewater management systems [4, 6]. In addition to effluent discharge, are nonpoint source pollutants, which also contribute to the pollution of surface water. With the quest for improved agricultural productivity fertilizers and pesticides are employed. When rainfall or irrigation water runs over land, it moves and deposits pesticides and nutrients into nearby water bodies [4, 6]. These pollutants disturb the health of the ecosystem, which necessitates interventions to alleviate the burden.
In recent years, biological technologies involving manipulation of naturally occurring microorganisms, such as fungi, to remove pollutants have been advocated [4]. Fungi are eukaryotes which may exist as individual cells, e.g., yeasts or as long chains of cells [7]. Saprophytic fungi grow on dead organic matter and take up nutrients by excreting digestive enzymes that break down complex nutrients to simpler forms [7]. Fungi are known for being adaptable organisms, with an ability to grow under environmental conditions of stress, and have become handy for bioremediation purposes [8].
Fungal mycelium are said to employ mechanisms such as biosorption, bioaccumulation and biodegradation in the remediation of pollutants/ xenobiotics [9, 10]. Biosorption, a passive process, occurs on the cell surface by ion exchange and complexation reactions with functional groups such as carboxyl, amine, hydroxyl and phosphate groups [11]. Bioaccumulation is an active metabolism dependent process, which involves transport of pollutants into the cells and partitioning into intracellular components [9]. The biodegradation mechanism entails the degradation of non-polymeric, recalcitrant pollutants to simpler elements by extracellular enzymes [9]. Several species of fungi have been studied and have demonstrated an exceptional ability in the uptake and removal of metals and other pollutants from waste and/or runoff water [1]. Fungal species, either live or in the form of dried biomass, have a very effective biosorption potential for metals such as Cu, Zn, Fe and Mn, and hold the ability to transform recalcitrant pharmaceutical compounds, as well as breakdown pesticides [12,13,14].
The use of fungi to degrade or sequester environmental pollutants, i.e., mycoremediation, has thus been deemed a technique that is not only cost-effective, but involves natural processes that do not produce toxic by-products [8]. One method of using fungi in mycoremediation is known as Mycofiltration, i.e., the treatment of contaminated water by passing it through a network of fungal mycelium [15]. A typical mycofilter comprises a burlap sack layered with substrate (e.g., straw or woodchips) and saprophytic mycelium [16]. The mycelium grows throughout the sack as a network of filaments, before being placed in the water bodies for remediation. Mycofiltration has shown to efficiently remove microbial pathogens from storm water, treat industrial brewery effluent, remediate heavy metal contaminated drinking water sources, as well as remove total nitrogen and phosphorus from a dairy lagoon waste [1, 15, 17,18,19].
Mycofiltration therefore has potential for use, to filter out and reduce levels of organic, inorganic and microbial contaminants in water. A synthesis of the evidence on mycofiltration of contaminated water via a systematic review will provide reliable and accurate data on the types of contaminants removed, and the mycofiltration removal efficiency based on a comparison of the levels of contaminants before and after filtration. The proposed systematic review will be conducted as part of an effort in the advancement of bioremediation interventions in the Maluti-a-Phofung municipality of eastern Free State of South Africa. Municipal reports of the Maluti-a-Phofung municipality show high WWTP-linked pollution events that subsequently affect the surrounding aquatic ecosystem health [20, 21], thus indicating a need for an intervention. The municipal authorities will be made aware of the preliminary review findings and bilateral discussions will help determine whether the mycofiltration technology could be adopted locally as a remediation tool for WWTP-linked pollution. The review findings will also have relevance to other stakeholders, such as researchers and environmentalists, interested in biological remediation interventions.
