This study aimed to evaluate the effect of microplastics on Spirulina sp., the pigment phycocyanin in Spirulina sp., and the effect of Spirulina sp. on the degradation of PE and PP plastic. The interaction of Spirulina sp. with microplstic (PE and PP) was conducted by adding the microplastic (500 mg/500 mL, with a size of 0.5–1 mm 2 ) to microalgae culture. The optical density was measured for 30 days to determine the growth of Spirulina sp. Harvesting was performed to obtain dry Spirulina sp biomass. Phycocyanin was obtained through extraction by mixing 0.1 g dry Spirulina sp. biomass with 25 ml of 1% CaCl 2 in an ultrasonic water bath at 50 kHz, 300 W at 30 °C for 15 min. The results showed that the growth rate of Spirulina sp significantly decreased (p < 0.05) with treatment of PE (SP + PE) (0.0228/day) and PP (Sp + PP) (0.0221/day), compared to the control (Sp-Control) (0.0312/day). Scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) analyses of Spirulina sp. biomass with the addition of PE and PP revealed surface damage of Spirulina sp. cells and loss of carboxyl groups from proteins in Spirulina sp. at wavelengths of 1397–1450 cm −1 . In addition, Spirulina sp. had decreased the intensity of amine and amide groups from proteins at wavelengths of 3280, 1637, and 1537 cm −1 in the microplastic treatment. The phycocyanin yield and protein content in Spirulina sp. control were 19.69% and 0.147%, respectively, which decreased by 10.7% and 0.121%, respectively, with PE treatment and by 8.7% and 0.108%, respectively, with PP treatment. Moreover, the investigation of PE and PP treated by Spirulina sp showed more significant changes of functional group indicated by the formation of hydroxyl (3286 cm −1 ), carbonyl (1700 cm −1 ), ester (1750 cm −1 ) and primary alcohol (1085 cm −1 ). The results of the EDX microplastic analysis showed a decrease in carbon in PE (1.62%) and PP (1.08%). These FTIR and EDX analysis also proved that microplastic has experienced degradation when treated by Spirulina sp cell culture.

Microplastics are polymer-based materials that require a variety of organic and inorganic chemical additives during the manufacturing process. These chemicals have an impact on aquatic organisms. This study aimed to quantify the impact of microplastics on the growth and quality of microalgae Spirulina sp. We studied the interaction between Spirulina sp. and 500 mg of polyethylene (PE) and polypropylene (PP) microplastics. Three glass bioreactors containing 2 L of Spirulina sp. were observed for 30 days. The first bioreactor was untreated and acted as a control. The second was treated with PE microplastic of 1 mm in size, and the third was treated with similarly sized PP microplastics. Each day, the optical density (OD) was measured to determine the rate of growth of the Spirulina sp. After harvesting, the Spirulina sp. biomass was dried in an oven at 30-35oC for 24 hrs and subsequently analyzed using Fourier transform infrared spectroscopy (FTIR). With PE treatment, the results showed a change in the organic structure on Spirulina sp., as well as a decline of polysaccharides and the loss of one peak at wave number 875.45 cm-1 . Meanwhile, in Spirulina sp. with PP treatment, two peaks that showed polysaccharides at wavelengths of 875.45 cm-1 and 1,245.67 cm-1 were lost. The results also indicated that microplastics had a significant impact on the growth and the quality of Spirulina sp., especially in decreased polysaccharide content.

The COVID-19 pandemic has mandated people to use medical masks to protect the public. However the improper management of disposable mask waste has led to the increase of marine pollution, in terms of water quality, and the decline in aquatic microorganisms. The aim of this research was to investigate the impact of disposable mask waste on fresh water and microalgae biomass quality. Disposable masks (untreated or treated with Enterococcus faecalis ) were placed in 10-L glass reactors containing fresh water or water containing algal Chlorella sp. and its growth supplements ( Chlorella medium) (four 10-L reactors in total) and kept in controlled conditions for 3 months. Water and biomass yield quality were evaluated using water quality analysis, spectroscopy, scanning electron microscopy (SEM), and proximate lipid and protein analysis. Disposable masks, incubated in either fresh water or Chlorella medium, affected several water quality parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD), dissolved oxygen (DO), and pH. Microplastic identification revealed that some fibers were present in the water following a 100-day treatment process. Fourier transform–infrared spectroscopy (FTIR) analysis was used to determine the change in important, organic functional groups and highlighted the disappearance of a peak at 1530 cm −1 corresponding to the primary protein (C–N) and the appearance of new peaks at 1651 cm −1 and 1270 cm −1 corresponding to methyl alcohol (CH 2 OH) and ketone (C = O), respectively. This indicated the detrimental effect of disposable mask fragmentation on the biomass quality. The SEM investigation has shown a damage to the surface membrane of Chlorella sp. cells. Altogether, disposable masks decreased the water quality and damaged microalgae by inhibiting their growth. Therefore, the disposable mask contaminated by various microbes, after being used by a human, may be one of the most dangerous hazards to the environment.

The depletion of fossil energy reserves and not environmentally friendly fossil energy emissions makes it necessary to use renewable energy as an alternative to replacing fossil energy. Biopellet is one of the renewable energy based on biomass that exists in Indonesia. Biopellets are produced from a base of abundant biomass. Thus, biopellets have the potential and promise to continue to be used as fuel by humans. The literature review includes the characteristics of biopellets and the application of biopellets as fuel. Biopellets can be made by mixing biomass with an adhesive with a concentration of 15% (w/w) then stirred until homogeneous and put into a pellet mill for printing. The pellets were dried in an oven for 30 minutes. Biopellet characteristically has complied with SNI 8021-2014 for parameters of ash content, fixed carbon content, caloric value, water content, and volatile matter content. The application of biopellet as a stove material also shows good performance for heat, efficiency, and emission parameters. In conclusion, biopellet is a renewable energy fuel based on biomass that has potential in the present and promising in the future.

Salah satu cara yang digunakan di Indonesia dalam menanggulangi berlimpahnya jumlah sampah plastik di lingkungan perairan adalah dengan menggantikan kantong plastik berbahan polimer polietilen (PE) dengan plastik oxodegradable yang disebut oxium. Penelitian ini dilakukan dengan tujuan untuk melihat pengaruh mikroplastik polietilen jenis HDPE (High Density Polyethylene) dengan plastic oxodegradable oxium. Penelitian dilakukan dengan menggunakan mikroalga Tetraselmis chuii sebagai mikroorganisme yang akan mendapat perlakuan mikroplastik dengan konsentrasi yang berbeda. Dari Hasil pengukuran optical density untuk menentukan laju pertumbuhan mikroalga Tetraselmis Chuii menunjukkan bahwa laju pertumbuhan Tetraselmis  dengan perlakuan mikroplastik polietilen mengalami penurunan yang signifikan dibandingkan dengan mikroplastik oxium. Konsentrasi mikroplastik ikut berperan dalam menentukan laju pertumbuhan Tetraselmis chuii di mana pada perlakuan mikroplastik oxium terjadi penurunan hingga 37,66% pada konsentrasi mikroplastik 300mg/500mL dan 81,70% pada perlakuan mikroplastik polietilen dengan konsentrasi 200mg/500mL. Mikroplastik polietilen dan oxium memberikan dampak negatif pada organisme tingkat rendah disebabkan oleh kemampuannya dalam melepas bahan aditif yang bersifat toksik sehingga diperlukan solusi yang lebih baik untuk menggantikan fungsi plastik dengan bahan yang lebih ramah bagi lingkungan hidup.  ABSTRACTOne of the methods used in Indonesia in tackling the abundance of plastic waste in the aquatic environment is to replace plastic bags made of polyethylene (PE) polymer with oxodegradable plastic called oxium. This research was conducted with the aim of examining the effect of HDPE (High Density Polyethylene) microplastic polyethylene with oxodegradable oxium plastic. The research was conducted using the microalgae Tetraselmis chuii as microorganisms that will receive microplastic treatment with different concentrations. From the results of optical density measurements to determine the growth rate of Tetraselmis chuii microalgae, it was shown that the growth rate of Tetraselmis with polyethylene microplastics treatment decreased significantly compared to oxium microplastics. The concentration of microplastics played a role in determining the growth rate of Tetraselmis chuii where in the oxium microplastic treatment there was a decrease of up to 37.66% at the microplastic concentration of 300mg/500mL and 81.70% at the polyethylene microplastic treatment with a concentration of 200mg/500mL. Polyethylene and oxyum microplastics have a negative impact on low-level organisms due to their ability to release toxic additives so that better solutions are needed to replace the function of plastics with materials that are more environmentally friendly.