Development and testing of a 3D-printable polylactic acid device to optimize a water bioremediation process

Abstract

In the present work, a remediation bioprocess based on the use of a native isolate of Chlorella vulgaris immobilized in an alginate matrix inside a polylactic acid (PLA) device is proposed. This microalga immobilized in alginate beads was previously shown to be useful for the reduction of several chemical and microbial contaminants present in the highly polluted water from the Matanza–Riachuelo watershed. However, these beads had a relatively short shelf life in the natural environment. To overcome this limitation, a 3D-printed PLA device was designed. PLA is a biocompatible and biodegradable material suitable for biotechnological applications. We used Erlenmeyers and stirred-tank bioreactors fed batch with Murashige Skoog (MS) culture medium or water from the Cildáñez stream (one of the water bodies of the aforementioned watershed) to estimate the growth kinetics parameters and the bioremediation capacity of immobilized-microalgal cells as an unconfined system (UcS) or a confined system (CfS) inside PLA devices on Cildáñez water. Although alga’s growth parameters were maximum in the UcS fed with MS medium as substrate, successful bioremediation of the target water was possible using the CfS: all inorganic nitrogen forms and total phosphorus were reduced at least by 90% after 5 days of bioprocess in an agitated bioreactor, whereas aerobic mesophilic bacteria decreased by about 85%. The number of coliforms also decreased. Standardized cytotoxicity tests using Allium cepa seeds carried out to prove the effectiveness of the bioremediation process, confirmed the high degree of decontamination achieved by the use of immobilized microalga confined in a 3D-printable PLA-device.

3D bioprinting in bioremediation: a comprehensive review of principles, applications, and future directions

“…PLA can be used to create frameworks for microbial films in water treatment or soil remediation, gradually degrading into harmless lactic acid ( Farah, Anderson & Langer, 2016 ). Another research work using PLA has led to the creation of a bioremediation system based on using a native isolate of Chlorella vulgaris immobilized onto an alginate matrix inside a PLA device, where the researchers were able to successfully demonstrate the reduction of all inorganic nitrogen forms and total phosphorus by 90% after 5 days, and a 85% decrease in aerobic mesophilic bacteria ( Marconi et al, 2020 ). Polyhydroxyalkanoates (PHAs) are another class of biopolymers produced by bacterial fermentation of sugars or lipids and are completely biodegradable, making them ideal for temporary structures in ecosystem restoration projects ( Kourmentza et al, 2017 ).…”

Extrusion-Based 3D Printing Applications of PLA Composites: A Review

“…A 3D-printed PLA-carbon black composite with controlled internal porosity was used to remove model VOC contaminants (benzene, toluene, and ethyl benzene) from water [184]. The pseudo-second-order rate constants for the VOC sorption were found to increase with a decrease of internal pore size of this 3D-printed sorbent [185].…”

“…When Chlorella vulgaris is immobilized in alginate beads, it is useful for the reduction of several chemical and microbial contaminants present in the highly polluted waters. However, alginate beads had a short shelf-life in the natural environment and a 3D-printed PLA composite device was used for the same purpose [184]. The growth kinetics parameters and the bioremediation capacity of immobilized microalgal cells were determined, and it was found that the successful bioremediation of the target water was possible using the novel device, where all inorganic nitrogen forms and total phosphorus were reduced at least by 90% after 5 days of bioprocess in an agitated bioreactor.…”

“…The growth kinetics parameters and the bioremediation capacity of immobilized microalgal cells were determined, and it was found that the successful bioremediation of the target water was possible using the novel device, where all inorganic nitrogen forms and total phosphorus were reduced at least by 90% after 5 days of bioprocess in an agitated bioreactor. Standardized cytotoxicity tests using "Allium cepa" seeds have shown the effectiveness of the bioremediation process [184].…”

Comparison of Light Intensity Effect On Microalgal Growth in Cactus-like and Cylindrical Photo Bioreactors

“…A wide variety of materials have been used for PBRs' construction, including glass, LDPE film, clear acrylic (polymethyl methyl acrylate, PMMA, also known by the trade names Plexiglas® and Perspex®), and Polylactic acid (PLA). When it comes to microalgae cultivation, PLA offers several advantages [13][14][15]: Firstly, its non-toxic and biocompatible nature ensures safety in cultivation environments, aligning with environmentally friendly practices owing to its biodegradability. PLA's transparency optimizes light utilization, enhancing the cultivation process, while its commendable thermal stability enables it to withstand moderate temperatures without deformation.…”