Microalgae Medium Research Articles

Objective: To investigate the use of biological ensiling of organic residues generated by pectiniculture as a nutritive medium in the production of the microalgae Tetraselmis suecica. Theoretical Framework: Biological ensiling is a process that transforms organic residues into a nutritive source through fermentation. In this context, pectiniculture residues, specifically the soft parts of fan shells, can be recycled and used

Objective: To investigate the use of biological ensiling of organic residues generated by pectiniculture as a nutritive medium in the production of the microalgae Tetraselmis suecica. Theoretical Framework: Biological ensiling is a process that transforms organic residues into a nutritive source through fermentation. In this context, pectiniculture residues, specifically the soft parts of fan shells, can be recycled and used as alternative media. Microalgae, such as T. suecica, are photosynthetic organisms that require nutrients for their growth, and their cultivation can benefit from these residues. Method: Twelve vertical bioreactors were used with three experimental treatments (T1, T2, T3) and treatments, one control (CT), with three replicates per treatment. The microalgae were inoculated at a density of 70 x 104 cells mL-1 in a culture volume of 80 L. Cultures were grown in open air with constant aeration. 0-, 60-, 70-, and 80-mL L-1 of the biological silage of fan shell soft parts (EBCA) were dosed. The silage was also chemically characterized and the growth of the microalgae and its relationship with temperature, salinity and pH were determined. Results and Discussion: The results showed that the dosage of 70 mL L-1 of EBCA in T. suecica cultures favors the growth of the microalgae. A significant increase in biomass and cell density was observed compared to the other treatments, indicating that this concentration of silage provides a suitable nutrient medium. The study also analyzed how temperature, salinity and pH conditions affect the growth of T. suecica, finding that certain optimal ranges of these factors can maximize biomass production. Research Implications: Our study demonstrates that pectin culture waste can be effectively recycled as a culture medium for T. suecica production, offering a sustainable and environmentally friendly solution for waste management. This could reduce reliance on traditional culture media and promote more sustainable practices in aquaculture and the microalgal industry. Originality/Value: This study stands out for its innovative approach in the use of organic waste from pectiniculture, such as the soft parts of the fan shell, for the generation of an alternative nutrient medium for microalgae. In addition, large volumes of fan shell wastes are currently being generated, so our work contributes to the management of these wastes.

Selective hydrolysis of traditional Chinese medicine residue into reducing sugars catalysed by sulfonated carbon catalyst and application of hydrolysate

The conversion of waste into high-value products has long been a focus point of research in green and sustainable chemistry. In this study, a novel value-adding strategy was devised to not only facilitate the resource utilization of biomass waste like Chinese medicine residue (CMR) and pomelo peel but also contribute to the advancement of microalgae cultivation. Sulfonated biochar PP-700-S was synthesized from pomelo peel waste, and its morphology and structural characteristics were analyzed. An effective method for the hydrolysis of CMR using PP-700-S as a catalyst in the aqueous phase was then explored, with a thorough investigation of the process and key influencing factors. Under the reaction conditions of 130 °C, 24 h, 20 mL H2O, CMR: PP-700-S = 1: 1, a 51.87 % yield of reducing sugars was directly obtained from the CMR, with PP-700-S exhibiting the selectivity of glucose production. Subsequently, the hydrolysate (HL-CMR) was utilized as a growth medium for microalgae, revealing that the presence of HL-CMR enhanced the nutrient balance in the medium, creating a more conducive environment for microalgae growth. Overall, this study presents a sustainable and efficient pathway for the utilization of lignocellulosic waste, facilitating the conversion of waste into higher-value products and contributing to the development of a green and sustainable science.

Biological treatment of swine wastewater—Conventional methods versus microalgal processes

BackgroundSwine wastewater (SWW) contains abundant organic carbon, nitrogen, and phosphorus, posing a significant risk of pollution and eutrophication with direct environmental release. Therefore, its proper treatment before environmental release is imperative. Conventional SWW treatment methods like stabilization ponds, aerobic processes, and anaerobic digestion are energy-intensive, with limited nitrogen and phosphorus removal and challenges in secondary sludge disposal. MethodsConventional methods described above, in addition to bacterial methods, have been discussed in detail. Microalgal bioremediation is an emerging technology for bioremediation and resource recovery from a circular economy perspective. Significant findingsConventional methods are dissimilatory and do not recover nutrients. On the other hand, the nutrients in SWW serve as a beneficial growth medium for microalgae. With its suitable nutritional composition, the resulting microalgal biomass can serve as supplements for livestock and aquaculture feed, generating additional revenue in microalgae-based SWW treatment. Microalgae-based processes enhance the SWW treatment efficiency and mitigate the common issue of secondary sludge pollution found in conventional treatment methods. This review offers comprehensive insights into traditional and microalgae-based SWW treatment methods and provides a comparative analysis of the various techniques and future research perspectives.

Examining the robustness of selected microalgae to grow in landfill leachate

Microalgae is widely recognized as a leading candidate for future bio-oil production, serving dual purposes: biodiesel generation and bioremediation. Identifying a sustainable cultivation medium is essential, aiming to minimize production costs. Landfill leachate emerges as a prospective growth medium for microalgae. However, due to the diverse substances within landfill leachate that may impede microalgal growth, careful selection of robust species becomes crucial. This study examined the growth of four microalgae species—Chlamydomonas reindhartii, Chlorella vulgaris, Chlorella ovalis, and Nannochloropsis oculata—in landfill leachate. Prior to utilization, the landfill leachate underwent treatment to remove the total ammonium nitrogen (TAN). Cultivation spanned 30 days, during which various parameters, including ammonium removal, growth rate, and oil content, were monitored. Initially, all microalgae exhibited a decline in numbers, succeeded by a subsequent increase in concentration after several days. Results revealed Nannochloropsis oculata to have the highest growth rate, while Chlamydomonas reindhartii displayed the lowest. Generally, the oil content of all species at the end of cultivation was lower than that of their respective inocula. Chlorella vulgaris exhibited the highest oil content, followed by Chlamydomonas reindhartii, Chlorella ovalis, and Nannochloropsis oculata.

Innovative multiple resource recovery pathways from EBPR wastewater treatment–derived sludge

Wastewater treatment–derived sludge is a growing concern. Environmental issues, rising sludge production rates, and stringent regulations create the necessity to seek for treatment and valorization alternatives. Sludge is a potential source of high-value materials which can be recovered and transformed into new products such as animal feeds; bioplastics; biofuels, biostimulants; or biobased fertilizers. Considering the current legal constraints hindering the use of certain waste streams, the objective of this work is to show the technical viability for obtaining multiple valuable products from sludge. The emphasis is placed on novel valorization pathways, such as microalgae and purple bacteria cultures growing over sludge. The obtained products are benchmarked against traditional methods for resource recovery such as direct land application and P recovery from ashes. Our results show, besides the nutrient (TKN 7.38, TP 4.41; K 0.47 g 100 g TS-1) and energy content (HHV 22.53 MJ Kg-1 TS), that sludge could be employed to produce a suitable growing medium for microalgae and purple bacteria cultures obtaining, in the latter, remarkable high contents of high-quality proteins (64.50 % dw) for potential valorization as animal feed ingredient. We also obtained nutrient rich microalgae biomass (TKN 7.10, TP 8.10; K 0.40 g 100 g TS-1) which could be used as inputs for biobased fertilizers or biostimulants preliminarily complying with the nutrient requirements in EU 2019/1009. Current global scenario, showing economic and supply risk uncertainties regarding food production inputs, generates the urgent need to find feasible pathways for obtaining recovered products such as the ones presented in this study.Graphical abstract

Capturing effects of filamentous fungi Aspergillus flavus ZJ-1 on microalgae Chlorella vulgaris WZ-1 and the application of their co-integrated fungi-algae pellets for Cu(II) adsorption.

Using filamentous fungi to capture unicellular microalgae is an effective way for microalgae recovery in water treatment. Here, fungi Aspergillus flavus ZJ-1 and microalgae Chlorella vulgaris WZ-1 isolated from a copper tailings pond were used to study the capture effect of ZJ-1 on WZ-1. The highest capture efficiency (97.85%) was obtained within 6h under the optimized conditions of 30°C, 150rpm, fungi-algae biomass ratio of 2.24:1, and initial pH of 9.24 in microalgae medium. The formed fungi-algae pellets (FAPs) were further used to remove Cu(II) from aqueous solution. Results showed that the FAPs formed at different capture times all adsorbed Cu(II) well, and the PAFs formed within 2h (PAFs2h) exhibited the highest Cu(II) adsorption capacity (80.42mg·g-1). SEM images showed that Cu(II) caused a change in the internal structure of PAFs2h from loose to compact, the mycelium shrunk, and the microalgal cells were concave. Cu(II) adsorption by PAFs2h was well conformed to the pseudo-second-order kinetics and the Langmuir isotherm (123.61mg·g-1 of theoretically maximum adsorption capacity). This work opens a way for applying FAPs in the remediation of heavy metal-contaminated wastewater, and the metal adsorption effect was determined by the capture amount of microalgae.

Usage of source separated urine for the biodiesel production from algal biomass

Urine is one of the most significant side-stream of domestic wastewater and this highly concentrated wastewater can be used as a growth medium for microalgae for the purpose of biodiesel production. In this study, autotrophic microalgae cultivation was achieved with changing dilutions of 5%, 10%, 20% and 40% (v/v). The highest biomass production was carried out with 5% of urine including medium as 1 g/L after the three sets of acclimation with increasing volumes. At the beginning of the microalgae cultivation, biomass productivity and nutrient accumulation was considerably low. However, biomass productivity was doubled after the acclimation studies with 23% of lipid content. During the cultivation ammonium nitrogen was treated more than 90% and the phosphorus removal was maximum 58%. Fatty acids and methyl esters (FAME) content of the biomass oil was showed the high quality of biodiesel production was possible with 33.01 ± 1.02% of saturated fatty acids and 86.62 ± 3.29% of C16-C18 fatty acids. Urine has high potential to be used for microalgae cultivation and the biodiesel production.

Sustainable integration of biofuel generation and domestic wastewater treatment by <em>chlorella vulgaris</em>

The production of microalgae biofuels has become promising because it is a renewable, non-polluting and non-competitive source such as food growing areas. This work has the objective of using the effluents generated by the Lorena Engineering School - EEL / USP as a growth medium for microalgae of the Chlorella vulgaris species, aiming at lipid production and treatment of effluents. The laps were completed in photobioreactor with effluent from the collection on alternate days. C. vulgaris showed good adaptation to the effluent, reaching a cell density of 1.92x107 cells.mL-1 and a dry biomass concentration of 1.74 g.L-1. The lipid content per gram of biomass was 0.095 to 0.164 mg.g-1. Concomitantly, between 54% and 78.74% of nitrate was dismissed and the chemical oxygen demand (COD) fell between 17.73% and 36.13%. With the results of statistical analysis (ANOVA and Tukey's test). Although lipid has been lower, the success of the microalga Chlorella vulgaris in this sense must have been similar to that of the same.

Integrated electrocoagulation-flotation of microalgae to produce Mg-laden microalgal biochar for seeding struvite crystallization

Developing sustainable materials for recovering and recycling nutrients from wastewater is critically needed for nutrients such as phosphorus that have a diminishing supply. Struvite crystallization is emerging as a promising strategy for phosphorus recovery which can be enhanced with seeding through microalgal biochar. The main bottleneck of using microalgae is its high harvesting cost. In this study, an integrated electrocoagulation-flotation (ECF) process is used to recover and at the same time modify the algal surface with magnesium anode and inert carbon cathode. Harvesting efficiency of 98% was achieved with 40.78 mA cm−2, 0.5 cm inter-electrode distance and energy consumption of 4.03 kWh kg−1 in 15 min. The harvested microalgae were pyrolyzed to obtain a yield of 52.90% Mg-laden microalgal biochar. Simultaneously, surface impregnation of 28% magnesium was attained as confirmed by Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Phosphorus recovery and struvite yield of 93.70% and 2.66 g L−1, respectively, were obtained from dosing 1.50 g L−1 Mg-laden microalgal biochar. Comparison of physicochemical characteristics of residual supernatant after microalgal harvesting and struvite recovery showed that the combined use of both the residuals can serve as a sustainable growth medium for microalgae. The overall operating cost of the integrated process was found to be 2.48 USD kg−1 with a total energy consumption of 10.76 kWh kg−1, which was found to be lower than conventional harvesting unit processes such as centrifugation and filtration. This novel approach can help attaining a circular bioeconomy by encompassing nutrient recovery and waste management in an integrated process.

Evaluation Of Spirulina, Nannochloropsis, and Chlorella Micro-algae Growth in Palm Oil Mill Effluent (POME) Medium with Variation of Medium Types and Time Adding Nutrient

POME is a kind of liquid waste produced by the crude palm oil industry. POME was not treated adequately, resulting in an issue for the environment owing to excessive levels of COD and BOD. Algae is a kind of bio-absorbent that may neutralize contaminants in liquid waste. Microalgae need carbon, nitrogen, and phosphorus-containing ingredients to flourish. These nutrients are necessary for photosynthetic carbon sources to be converted into biomass. POME includes a high concentration of C, N, and P; hence this research aims to investigate the potential of POME as a medium for the development of algae such as Spirulina, Nannochloropsis, and Chlorella. The experiment was carried out by varying the nutrients, water type, and time of nutrient feeding. Urea and sodium bicarbonate were the nutrition. Preparing the medium, culturing the microalgae, assessing biomass, counting the algae cells, and creating a calibration curve were the procedures in the experiment. The findings revealed that POME is the best medium for microalgae, that Spirulina grows better in POME than Chlorella and Nannochloropsis, and that providing nutrients every 2 days was better than introducing nutrients at the beginning and without adding nutrients.

Impact of High-Pressure Homogenization on the Cell Integrity of Tetradesmus obliquus and Seed Germination.

Microalgae have almost unlimited applications due to their versatility and robustness to grow in different environmental conditions, their biodiversity and variety of valuable bioactive compounds. Wastewater can be used as a low-cost and readily available medium for microalgae, while the latter removes the pollutants to produce clean water. Nevertheless, since the most valuable metabolites are mainly located inside the microalga cell, their release implies rupturing the cell wall. In this study, Tetradesmus obliquus grown in 5% piggery effluent was disrupted using high-pressure homogenization (HPH). Effects of HPH pressure (100, 300, and 600 bar) and cycles (1, 2 and 3) were tested on the membrane integrity and evaluated using flow cytometry and microscopy. In addition, wheat seed germination trials were carried out using the biomass at different conditions. Increased HPH pressure or number of cycles led to more cell disruption (75% at 600 bar and 3 cycles). However, the highest increase in wheat germination and growth (40–45%) was observed at the lowest pressure (100 bar), where only 46% of the microalga cells were permeabilised, but not disrupted. Non-treated T. obliquus cultures also revealed an enhancing effect on root and shoot length (up to 40%). The filtrate of the initial culture also promoted shoot development compared to water (21%), reinforcing the full use of all the process fractions. Thus, piggery wastewater can be used to produce microalgae biomass, and mild HPH conditions can promote cell permeabilization to release sufficient amounts of bioactive compounds with the ability to enhance plant germination and growth, converting an economic and environmental concern into environmentally sustainable applications.

Microalgae growth and diversity in anaerobic digestate compared to synthetic media

Economizing microalgal cultivation is a considerable milestone targeted by efforts put into microalgal biorefineries. In light of that, the present study was aimed to explore the potential of using anaerobic liquid digestate (ALD) as culture media to grow microalgae and compared it with three different synthetic media (i.e., N8, BBM, and M8) in terms of biomass yield, fatty acid composition, and nutrient utilization/recovery. Moreover, a mixed culture of wild-type microalgae was employed in this study owing to the ability of mixed cultures to survive extreme conditions, eliminating the risk of losing the culture easily, as it mostly happens with pure cultures. The highest nutrient yield coefficients were achieved when the mixed microalgae culture was cultivated in ALD, where the yield coefficient for nitrogen (YN) and yield coefficient for phosphorus (YP) were 10.7 mg biomass mg-1 N and 98 mg biomass mg-1 P, respectively. The highest lipid content (34%) and the highest concentrations of C16:0 (114 mg L-1) and C18:0 (60.9 mg L-1) were also recorded when the mixed microalgae culture was cultivated in ALD. Furthermore, the polyunsaturated fatty acids (PUFA) content also increased significantly in ALD, a beneficial phenomenon as PUFAs in microalgae allow them to adapt more effectively to extreme conditions. Based on the microbial community analysis performed using the multi-marker metabarcoding approach, Diphylleia rotans, Synechocystis PCC-6803, Cyanobium gracile PCC 6307, and Chlorella sorokiniana were identified as the most abundant species in the ALD growth. Overall, based on the findings of the present study, ALD could be used as a promising cultivation medium for microalgae, offering a process integration approach to combine anaerobic digestion and algae cultivation as an effective way to simultaneously treat the high-strength dark-colored ALD and valorize it into profitable byproducts.

Thermal and energy performance of a user-responsive microalgae bioreactive façade for climate adaptability

As a recent trend in the energy-efficient architecture, microalgae bio-reactive façades can control buildings’ thermal loads by the responsiveness to solar radiations and adaptive variations in culture density. Although these smart systems can provide adaptable shading during the year, they cannot meet the varying thermal comfort needs of building users in a short time because the microalgae medium’s culture remains almost unchanged during the day. This paper reports on an innovative method that helps microalgae bioreactive façade respond to solar radiation and users’ thermal needs in a short time. To achieve it, a smart window panel will be introduced, which contains two remotely-controlled adjustable bioreactors which can regulate the algae medium in height based on the users’ thermal needs. This novel panel can serve as a bio-adaptable sunshade integrated with the building facade. Thus, the internal building thermal loads can be adjusted via the height of the bioreactor façade. Experimental and simulation research was conducted to compare the thermal performance of bioreactor facades at different microalgae medium height levels in the BSk climate zone. The results indicate that indoor and outdoor temperature differences for full, ¾, ½, and ¼ medium height level every 15-minute time interval are 12.55, 11.50, 10.87, and 6.53, respectively, indicating that the full-height level has the most influence to control the thermal load of the system. According to the results, the bioreactor façade with adjustable medium height greatly impacts building thermal control in a short time.

Effects of anode materials in electricity generation of microalgal-biophotovoltaic system - part I: Natural biofilm from floating microalgal aggregation

A biophotovoltaic (BPV) system is an emerging photo-bio-electrochemical technology that promises bioelectricity generation through the photosynthesis of exoelectrogenic microorganisms. An algal pool or floating photobioreactor with algae cultivation medium is a potential electron source for sustainable operation of such BPV device. Therefore, bioelectricity generation from algae cultivation medium should be studied to demonstrate this value-added feature. In natural conditions, self-aggregated microalgae form biofilms on the medium surface. One technical concern is that previous studies emphasized the role of anode materials and biofilm formation for the enhancement of electron transmission in BPV device, whereas cell performance by free-floating microalgae medium and natural biofilm still has research value. Hence, cell performance under different anode materials is a crucial decision-making factor of the system with a natural biofilm. In this paper, the experiment was repeated three times to investigate the bioelectrical power generation of BPV device in natural conditions from using three different anode materials, namely graphite, indium tin oxide (ITO)-coated glass, and ITO-coated plastic. In the experiments, BPV devices with ITO anode experienced power overshoot problems by the use of natural floating Spirulina (Arthrospira) platensis aggregation. ITO-coated glass- and plastic-based BPV devices produced maximum power densities of 0.118 mW/m2 and 0.215 mW/m2, respectively. The findings are expected to contribute to further understanding on the correlation of these parameters with regards to power generation by BPV device.

Mixotrophic Cultivation of Microalgae in Cassava Processing Wastewater for Simultaneous Treatment and Production of Lipid-Rich Biomass

Cassava processing wastewater (CPW) is a highly polluting, liquid residue of cassava processing, usually discarded or treated anaerobically. However, it can serve as a low-cost culture medium for microalgae. After a preliminary evaluation of the growth of 10 microalgal strains in diluted CPW, the microalgae Haematococcus pluvialis SAG 34−1b and Neochloris (Ettlia) oleoabundans UTEX 1185 were selected for cultivation in CPW without a supply of additional nutrients and evaluated for their growth, lipid production, and nutrients removal. Maximal biomass concentrations of 1.79 g·L−1 for H. pluvialis and 3.18 g·L−1 for N. oleoabundans were achieved with 25% CPW medium on the 13th day of growth. The algae H. pluvialis and N. oleoabundans removed 60.80 and 69.16% of the chemical oxygen demand, 51.06 and 58.19% of total nitrate, and 54.68 and 69.84% of phosphate, respectively. On average, lipid productivities reached 0.018 and 0.041 g·L−1 day−1 for H. pluvialis and N. oleoabundans, respectively. Therefore, cultivating these microalgae in diluted CPW is a promising treatment for cassava wastewater with simultaneous valuable biomass production.

Potential for Biomass Production and Remediation by Cultivation of the Marine Model Diatom Phaeodactylum tricornutum in Oil Field Produced Wastewater Media

While oilfield produced water (PW) is one of the largest, unclaimed wastewater streams of the oil industry, it could potentially be used as a cultivation medium for microalgae. Microalgae could help with the remediation of this water while also delivering biomass that can be transformed into valuable byproducts such as biofuels. The coupling of these two purposes is expected to cut production costs of biofuels while aiding environmental protection. In this study, we compared the cultivation capacity of the marine model diatom Phaeodactylum tricornutum in media at varying salinities and in media composed of PW from two oilfields in the Central Valley of California that differed drastically in the concentration of inorganic and organic constituents. Specifically, we measured the carrying capacity of these media, the maximum growth rates of P. tricornutum, its cellular lipid accumulation capacity, and its capacity to remediate the most polluted PW source. Our study shows that P. tricornutum can successfully adjust to the tested cultivation media through processes of short-term acclimation and long-term adaptation. Furthermore, the cultivation of P. tricornutum in the most heavily polluted PW source led to significant increases in cell yield and improved photosynthetic capacity during the stationary phase, which could be attributed chiefly to the higher levels of nitrate present in this PW source. Chemical water analyses also demonstrated the capability of P. tricornutum to remediate major nutrient content and potentially harmful elements like fluorine and copper. Because P. tricornutum is amenable to advanced genetic engineering, which could be taken advantage of to improve its cultivation resilience and productivity in an economic setting, we propose this study as a step towards essential follow-up studies that will identify the genetic regulation behind its growth in oilfield PW media and its remediation of the PW constituents.

Effect of Dilution on Nitrogen Removal from Ammonia Plant Effluent using Chlorella vulgaris and Spirulina platensis

In this study, the removal of nitrogen from effluent of ammonia plant by Chlorella vulgaris and Spirulina platensis was investigated. For this purpose, microalgae were cultivated in three diluting percentage of the wastewater (1, 3, and 5%) at 29±1 ◦C and light intensity at surface of culture were adjusted to 150 µmol photon / (m2. s). The results showed that Spirulina platensis is more capable than Chlorella vulgaris to grow in high levels of total nitrogen concentration. Also, maximum biomass production rate happened in 1% diluted samples for Chlorella vulgaris and 3% for Spirulina platensis. Furthermore, Chlorella vulgaris reduce total nitrogen concentration up to 55%. This value for Spirulina platensis was about 96%. However, for both species the removal of nitrogen in 1% diluted wastewater was maximum. According to the results of diluted wastewater of ammonia plant, it is a suitable culture medium for microalgae and it can be used to remove the nitrogen before entering the wastewater in nature.

Circulation of anodic effluent to the cathode chamber for subsequent treatment of wastewater in photosynthetic microbial fuel cell with generation of bioelectricity and algal biomass

Synthetic wastewater containing 1500 mg L−1 of COD was treated in the anode chamber for 5, 10, and 20 d. An anode chamber was conducted under anaerobic conditions with mixed culture bacteria inoculum attached to the anode. Anodic effluent was transferred to the cathode chamber for further treatment for 5, 10, and 20 d as the growth medium of Chlorella vulgaris. The microalgal photosynthesis process provided oxygen for the cathodic reaction. In 5 d of anodic hydraulic retention time (HRT), the effluent contained high COD, resulting in low power generation in the P-MFC due to the heterotrophic metabolism carried out by microalgae diminishing photosynthesis. However, high biomass productivity up to 0.649 g L−1 d−1 was obtained in the subsequent treatment of 5 d in the cathode chamber. An anodic HRT of 10 d resulted in higher power generation (0.0254 kWh kg−1 COD), and higher COD removal efficiency up to 60%. A further 10 d treatment in the cathode chamber increased the COD removal efficiency up to 74%. Anode and cathode chambers combined removed 79% of NH4+–N concentration from the original synthetic wastewater within 20 d. This study demonstrated that the anodic effluent of the P-MFC can be utilized in the cathode chamber as a growth medium for microalgae if conducted with appropriate HRT in the anode. P-MFC provides a promising sustainable solution for wastewater treatment while generating electricity and algal biomass as by-products.

Organic Substances Reduction in Palm Oil Mill Effluent (POME) After Cultivation with Locally Isolated Microalgae

This work aims to study the ability of locally isolated microalgae to reduce organic substances in Palm Oil Mill Effluent (POME) which was carried out on a laboratory scale. Inoculum with a concentration of 20% was cultivated into POME media with various concentration of LP100 (without dilution), LP75 (25% dilution), and LP50 (50% dilution) using aeration and continuous lighting for 15 days in vessels with a lighting intensity of 1300 lux. Biomass of microalgae were observed daily and analyzed in dry weight by means of spectrophotometry using 624 nm wavelength to get their growth by determining the content of algae biomass. The reduction of organic substances in POME was observed by measuring the COD, BOD phosphate, ammonium, nitrate, and fatty oil parameters every 3 hours with the standard method. Results show that the growth of microalgae occurred well in POME media at LP75 and LP50 concentrations with inoculum concentration of 20% under 1300 lux lighting intensity conditions with a continuous 24-hour lighting and aeration cycle that obtained biomass content of 0.92 and 1.08 g-DW/L, respectively. The presence of microalgae in POME at concentration of LP75 for 12 days reduced organic substances and nutrients reaching 80.74% - 99.70%. Some parameters that were reduced include BOD (99.35%), COD (89.57%), TSS (89.68%), Phosphate (97.70%), Ammonium (95.08%), Fatty Oil (99.70%), and Nitrates (80.74%). This study concludes that locally isolated microalgae have ability to treat POME safely for environment and as a growing medium for microalgae followed by a decrease in organic substances.

Treatment and Re-Use of Raw Blackwater by Chlorella vulgaris-Based System

In this study, we examined a Chlorella vulgaris-based system as a potential solution to change liquid waste, such as blackwater, into valuable products for agriculture while protecting waters from pollution without technical demanding pre-treatment. To evaluate the possibility of nutrient removal and biomass production from raw blackwater, four blackwater dilutions were tested at lab-scale: 50%, 30%, 20%, and 10%. The results showed that even the less diluted raw blackwater was a suitable growth medium for microalgae C. vulgaris. As expected, the optimum conditions were observed in 10% blackwater with the highest growth rate (0.265 d−1) and a nutrient removal efficiency of 99.6% for ammonium and 33.7% for phosphate. However, the highest biomass productivity (5.581 mg chlorophyll-a L−1 d−1) and total biomass (332.82 mg dry weight L−1) were achieved in 50% blackwater together with the highest chemical oxygen demand removal (81%) as a result of the highest nutrient content and thus prolonged growth phase. The results suggested that the dilution factor of 0.5 followed by microalgae cultivation with a hydraulic retention time of 14 days could offer the highest biomass production for the potential use in agriculture and, in parallel, a way to treat raw blackwater from source-separation sanitation systems.