Bioenergy production and nutrients removal by green microalgae with cultivation from agro-wastewater palm oil mill effluent (POME) - A review

Environmental pollution specifically wastewater is gaining attention both in the developed and developing countries. Malaysia is considered as one of the major palm oil producers in the world. Therefore, it is important to develop an environmental friendly and economic method to treat palm oil mill effluent (POME). The wastewater can serve as an economical nutrient source or substrate that can support the cultivation of microalgae. This can be a great nutrient for algal cultivation at the same time as remediating effluent and generating biomass. Nowadays, many microalgae species are being investigated to determine their potential and effectiveness for phytoremediation application, especially high growth rate. However, using synthetic media for growing microalgae in a mass scale is costly. It is acknowledged that POME (as nutrients enriched media) assisted enhanced microalgae growth under certain condition can considerably reduce the presence of organic and inorganic compounds. In this review, the potential of wide range of the predominant microalgae species with main focus on green microalgae (high removal efficiency): Chlamydomonas sp and Chlorella sp were investigated. Moreover, we discussed about the history, methods and future prospects in nutrients removal by green microalgae comprehensively. This review discusses several potential strategies for tackling the environmental issue generated by agro-waste water POME with enhancement of biomass productivity which can be used as an alternative for energy production

Palm Oil Mill Effluent as an Environmental Pollutant

In recent decades, Malaysia has been known as one of the world’s leading producers and exporters of palm oil products. Every year, the number of palm oil mills increases rapidly, thus increasing the capacity of fresh fruit bunch waste or effluent discharge. Based on the data from the Malaysian Palm Oil Board in 2012, Malaysia produced 99.85 million tons of fresh fruit bunch (FFB) per year. However, about 5–5.7 tons of water was required in order to sterilize the palm fruit bunches and clarify the extracted oil to produce 1 ton of crude palm oil resulting in 50% of the water turning into palm oil mill effluent (POME). POME is one of the major environmental pollutants in Malaysia. The characteristics of POME and its behavior, if discharged directly, in water are described in this chapter. The suspended solid and nutrient content in POME could be able to support the growth of algae. This chapter aims to demonstrate that POME could be used as a main source for algae production, and this effluent is one of the main environmental problems in the tropical region especially in Malaysia

Importance of glucose and pseudomonas in producing degradable plastics

In this study, bacteria, P. oleovorans, was studied for its ability to produce PHA with glucose, fructose and sucrose as carbon sources that was grown at 25°C. The functional groups of the extracted PHA granules were identified as C=O group by Fourier transform Iinfrared (FTIR) spectroscopy analysis. The drastic absorption band at approximately 1720 cm-1 indicates the stretching vibration of the C=O groups in the PHA polyester. The optimized production of PHA was done by RSM (Response Surface Method) through various growth parameters. The best condition of productivity range for glucose is 93.4419 g/L. In addition, the highest PHA production after optimization is 2.28236 g/L with a desirability of 0.986 g/L, meanwhile the highest amount of PHA produced from P. oleovorans was 2.30 g/L

Manufacture of Low-cost Activated Carbon using Sago Palm Bark and Date Pits by Physicochemical Activation

Two raw materials, sago palm bark (SPB) and date pits, were utilized as precursors to prepare high porosity activated carbon (AC). The porosity of these two raw materials was compared with that of commercial AC made from coconut shells. The physicochemical activation method was used for AC preparation, and it consisted of two steps, carbonization and activation. The activation process was performed using zinc chloride (ZnCl2) as an activation agent. N2 adsorption-desorption analysis was carried out to characterize the porosity of AC. Thermogravimetric analysis (TGA) was conducted for the two raw materials. The adsorbent made from SPB, which showed the maximum surface area of 1634 m2/g at the 700 °C activation temperature for one hour, while the surface area of prepared AC from date pits was 1367 m2/g. Both prepared ACs had a larger surface area than commercial AC made with coconut shell (1348 m2/g)

The effects of caffeine, gliclazide, and prazosin on the performance and microbial diversity in an up-flow anaerobic sludge blanket (UASB) reactor

A laboratory-scale up-flow anaerobic sludge blanket (UASB) reactor was deployed in this study to examine the relationship between pharmaceutical compounds and anaerobic process performance. The reactor successfully biotransformed up to 87–99% of psychostimulant caffeine, anti-diabetic drug gliclazide, and anti-hypertensive drug prazosin during 92 days of operation. At the same time, fluctuations were recorded for the methane gas production, and also the domination of acetic acid and propionic acid in the presence of pharmaceutical compounds was measured. The results from 16s rRNA sequencing revealed that these compounds stimulated the growth of hydrogenotrophic methanogens, mainly Methanobrevibacter and Methanobacterium, while shifting the compositions of hydrolytic and fermentative bacteria. These outcomes proved the capability of the pharmaceutical compounds to influence the process performance by changing the microbial compositions in the anaerobic reactor

Removal of Acid Orange 7 dye from wastewater using combination of ultraviolet radiation, ultrasonic method, and MgO nanoparticles

Background: Industrial dyes are toxic and carcinogenic, therefore, they should be removed from wastewater. The aim of this study was to investigate the removal of acid orange 7 Dye from wastewater using ultraviolet (UV) radiation, MgO nanoparticles, ultrasonic method alone and in combination with each other. Methods: The effects of some factors such as temperature, pH, hydraulic retention time (HRT), UV power, and concentration of MgO nanoparticles on the removal of Acid Orange 7 dye from synthetic wastewater using different methods were investigated. Also, adsorption isotherms for MgO nanoparticles and kinetics for UV radiation were investigated. Results: The optimum HRT was 55 minutes while the temperature was not effective in dye removal using the ultrasonic method. Under optimum conditions for UV irradiation method (HRT = 70 minutes, UV power = 170 mW/cm2, and temperature = 10˚C), 58% of the dye was removed. However, under optimum conditions for MgO nanoparticles method (HRT = 15 minutes, temperature = 20˚C, and ratio of MgO nanoparticles to the initial dye concentration = 67.2), 82% of the dye was removed. By combining these methods, the dye removal efficiency was significantly increased. The combination of ultrasonic method and MgO nanoparticles had no significant effect on increasing the dye removal efficiency from wastewater. It was revealed that dye removal using UV radiation can be described by the first-order kinetics. Conclusion: According to the results, UV radiation has a synergistic effect on the dye adsorption process by MgO nanoparticles. Therefore, the combination of these methods can be effective for the removal of dye from wastewater. Keywords: Azo compounds, Ultraviolet rays, Ultrasonic method, Nanoparticles, Waste water, Kinetic

Effect of various pretreatment methods on sugar and ethanol production from cellulosic water hyacinth

Effects of acid, alkali, ionic liquid (IL), and microwave-alkali pretreatments on cellulosic water hyacinth (WH) were investigated based on the total reducing sugars (TRS) and ethanol production. For the first time, IL pretreatment with (1-Ethyl-3-methylimidazolium acetate ([EMIM][Ac]) was used for WH, and the efficiency was compared with the other methods. Cellulase and Saccharomyces cerevisiae were fermented together for 72 h. Based on the results, all pretreatment methods effectively increased the sugar content as well as the ethanol yield. Untreated WH had 25 ± 1.5 mg/g of TRS, which was increased to 157 ± 8.2 mg/g, 95 ± 3.1 mg/g, 51 ± 4.2 mg/g, and 45 ± 2.6 mg/g via alkali, microwave-alkali, acid, and IL pretreatments, respectively. The highest TRS level of 402 mg/g was obtained in 24 h and 6.2 ± 0.4 g/L of ethanol in 48 h of fermentation with the alkali-treated WH. The ethanol production was followed by other treatment methods of WH in the order of microwave-alkali, acid, and IL. The results indicated that the ethanol production from WH was related to the type of pretreatment as well as the TRS production

Techno‐economic analysis of direct combustion and gasification systems for off‐grid energy supply: A case for organic rankine cycle and dual fluidized‐bed

Biomass is one of the most versatile sustainable energy sources. This versatility allows utilization of different biomass feedstock using a verity of conversion techniques. Often, a biomass-to-bioenergy conversion method is selected depending on the application, end-use product, and the type of feedstock. In many applications such as residential energy supply, it is possible to select amongst various technologies. Although, there exist several challenges such as cost-effectiveness and sustainability that constrains bioenergy development. To this end, this research elaborates on the impacts of different conversion methods on techno-economic performance of bioenergy systems for residential energy supply. In this context, Organic Rankine Cycle based on direct combustion, and Dual Fluidized-Bed technology based on gasification were selected for that purpose. A techno-economic comparative analysis illustrates that the primary product of the system and fuel cost are the two most important factors in feasibility assessment. The negative impact of feedstock price was more severe on the Organic Rankine Cycle. For wood chips prices below 55$/t, Organic Rankine Cycle could be the better option due to lower capital and maintenance costs. In contrast, Dual Fluidized-Bed could better tolerate the variation of feedstock price; offering 8$/t wood chips