Cork as a sustainable carbon source for nature-based solutions treating hydroponic wastewaters – Preliminary batch studies

Abstract

Reusing by-products is an important strategy to ensure the preservation of natural capital and climate change mitigation. This study aimed at evaluating the potential of cork granulates, a by-product of winery industry, as an organic carbon (OC) source for the treatment of hydroponic wastewaters. First, chemical characterization was performed and discussed. Secondly, batch studies were performed using synthetic hydroponic wastewater to understand the role of particle size (PS), pH and contact time (CT) on the release of OC. The suberin is the major compound, representing >50%. It was noticed that a variance on the content of suberin across species, within the same species and depending on the extraction part (belly, cork and back) could be expected. >60% of the sample is composed by carbon while <1% was nitrogen (high C:N ratio), indicating a low risk of releasing organic nitrogen. The statistical results suggested that the main effect of PS on the release of OC is greater than both, CT and pH. The chemical release of OC gets slower with time, being this effect greater as the PS increase. Moreover, estimations showed that using the 4 mm PS, the amount of water treated would be twice the amount if the 8 mm PS had been used. The PS seems to play an important role at design nature-based solutions (NBS) focused on denitrification. The surface response methodology indicates a significant negative interaction between CT and PS suggesting that the mathematical model could be used for further optimization studies. The reuse of organic by-products as filter media seems to be an economic and environmentally friendly alternative to enhance denitrification in NBS, while preserving natural capital. However, further real scale and long-term experiments are needed to validate cork's potential as an "internal" OC source for NBS.

Nature-Based Solutions and Circularity in Cities

“…Few studies have shown the potential of using recycled material for structure of green walls such as polyethylene modules [25], recycled PET bottles [26], or cork boards [27]. Nowadays, there is also a great variety of waste materials being tested and validated in terms of their performance to be used as filter media in NBS: cork [28], coconut shell [23], recycled glass beads [29], mix of coir fibber and perlite [30], and crushed autoclaved aerated concrete [31]. One can conclude that creating new applications to waste materials is the basis for the establishment of an integrative urban chain, where the demand for manufactured products and disposal of waste is reduced.…”

Returning to Nature for the Design of Sorptive Phases in Solid-Phase Microextraction

“…Since it was first described as an adsorbent in 2005, [20] its use in environmental applications for the removal of a variety of organic and inorganic pollutants has gained considerable attention, and a large number of research articles, as well as reviews, covering this approach have been published [17,[21][22][23][24][25][26]. The cork employment in sample preparation for microextraction purposes was firstly reported in…”

“…Therefore, its formidable characteristics are promising resources with potential application on adsorption technologies [18]. Herewith cork is a natural, cheap, renewable, fully sustainable, and biodegradable raw material with a very relevant advantage over other carbonaceous materials to be explored as a sorbent in many applications [19].Since it was first described as an adsorbent in 2005, [20] its use in environmental applications for the removal of a variety of organic and inorganic pollutants has gained considerable attention, and a large number of research articles, as well as reviews, covering this approach have been published [17,[21][22][23][24][25][26]. The cork employment in sample preparation for microextraction purposes was firstly reported in…”

How Has the Wine Sector Incorporated the Premises of Circular Economy?

“…Number of papers References 2019 8 [8], [37], [38], [39], [40], [41], [42], [43] 2018 23 [3], [7], [31], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [ literature review. Fig.…”