Mixed Light-emitting Diodes Research Articles

Influence of influent methane concentration on biogas upgrading and biogas slurry purification under various LED (light-emitting diode) light wavelengths using Chlorella sp.

Raw biogas is a valuable renewable energy but usually requires upgrading. The mixed LED (light-emitting diode) light wavelengths achieved much better microalgae growth than that of the monochromatic. The best LED light wavelength mix ratio for both biogas upgrading and biogas slurry nutrient removal was the red:blue ratio of 5:5. Lower influent CH4 (methane) concentration achieved higher biogas slurry nutrient removal efficiency, whereas moderate influent CH4 concentration achieved the best biogas upgrading effect. Therefore the optimal parameters were determined to lie between the low and moderate influent CH4 concentrations and the mixed red:blue ratio of 5:5 LED light wavelengths. They achieved the best biogas upgrading and biogas slurry nutrient purification effects with the following values: 92.60 ± 2.24% (v/v) of upgraded biogas CH4 concentration, 85.73 ± 4.26% of chemical oxygen demand removal efficiency, 73.21 ± 2.51% of total nitrogen removal efficiency, and 73.89 ± 4.82% total phosphorus removal efficiency.

Performance of mixed LED light wavelengths on biogas upgrade and biogas fluid removal by microalga Chlorella sp.

Chlorella sp. is a microalga that could be utilized effectively in the simultaneous biogas upgrade and biogas fluid nutrient removal. Mixed light-emitting diode (LED) light wavelength treatments (red:blue=1:9, 3:7, 5:5, 7:3, and 9:1) were more appropriate for microalgal growth than monochrome LED light wavelength treatments (monochrome red, blue, and white). The most appropriate mixture ratios for biogas upgrade were red:blue=7:3 and red:blue=5:5. For biogas fluid nutrient removal, the most appropriate mixture ratio was red:blue=5:5. Therefore, the optimal mixture ratio of LED light wavelengths was red:blue=5:5. Under this treatment, components of upgraded biogas content (v/v) were 93.68±3.25% CH4, 1.57±0.42% CO2, 0.99±0.06% O2, and 3.80±0.34% H2O. The highest biogas fluid removal efficiencies of chemical oxygen demand, total nitrogen, and total phosphorus reduction were 78.91±2.75%, 73.05±2.04%, and 67.54±1.46%, respectively.

Effects of LED Light Illumination on Germination, Growth and Anthocyanin Content of Dandelion (Taraxacum officinale)

Dandelion has been widely utilized for medicinal and edible purposes. This research was conducted to evaluate the effect of supplemental LED (light-emitting diode) light on germination, growth characteristics and anthocyanin content of dandelion (Taraxacum officinale) seedling using LED blue (460 nm), red (660 nm, R), blue + red (B:R=6:4) and fluorescent lamp light treatment. By LED illumination to T. officinale seed germination speed was delayed, and germination rate was the highest in the fluorescent light. The growth characteristics (plant height, number of leaves, root length and fresh weight) were greatly influenced by supplemental LED light compared with control treatment, and the growth promotion was the most effective in the red LED illumination. After 60 days of red and mixed LED light treatments, anthocyanin content of dandelion plants was significantly changed. The anthocyanin content was increased by 12~19 mg/100 g under the red LED and the mixed light conditions compared with the control and the blue LED. Results indicate that illumination with red and mix LEDs, compared with other light treatments, is beneficial for promotion of growth and anthocyanin content in dandelion.

LED광의 파장을 달리하여 재배한 새송이버섯의 식품기능적 특성

The food functional properties of Pleurotus eryngii cultivated with different wavelengths of light-emitting diode (LED) light were analyzed in this study. The levels of total soluble solids of Pleurotus eryngii increased with all the LED lights, except mixed LED light (, and ). Thirty one kinds of components were detected by analyzing the free amino acids. The total free amino acid contents had a slightly higher tendency in the control group, but the ratios of eight essential amino acids among the total amino acids of Pleurotus eryngii cultivated under all the LED lights, including the blue light (blue, , and ) and the green light, were higher than that in the control group. K was the highest-content of mineral, and Mn was the lowest-content. The Ca content increased through cultivation under all the LED lights, except the blue light, but the Fe content (under the green and lights), K content (under the red and UV-A lights) and Mg content (under the , UV-A and red lights) increased under the exclusive LED light. The total phenolic compounds increased by cultivation under all the LED lights, except the UV-A and mixed lights ( and ). The DPPH radical scavenging activity was also improved by all the LED lights, except the mixed light ().

Influence of mixed LED radiation on the growth of annual plants

We investigated the effect of mixed radiation from light-emitting diodes (LEDs) on the growth and flowering of ageratum, marigold, and salvia bedding plants. Blue, red, and far-red lights were applied under controlled environmental conditions for 28 d. Both the combination of blue-plus-red radiation as well as fluorescent lighting treatment (control) caused increases in dry weights, but shoot lengths were shortest when plants were exposed to blue plus red light compared with either red or blue plus far-red treatments. The number of floral buds as well as the occurrence of flower opening for ageratum and salvia plants was also enhanced under the blue plus red mixture. Likewise, carbohydrate accumulation was stimulated by that combination compared with the other radiation treatments.

Growth of Tsuru-rindo (Tripterospermum japonicum) culturedin vitro under various sources of light-emitting diode (LED) irradiation

We studied the effects of light generated by LEDs on the growth of Tsururindo (Tripterospermum japonicum) shoots. Apical shoots (2–3 cm long) were cultured on MS basal media supplemented with 3% sucrose, and were maintained for four weeks under five different light qualities: F (fluorescent lamp), red LED (R), 70% red + 30% blue LED (R7B3), 50% red + 50% blue (R5B5), or blue LED (B). Rooting was promoted by red light (100%) but was inhibited by blue light. Plant growth, as defined by root number, fresh weight, and chlorophyll content, was generally healthier for cultures irradiated with mixed LEDs, and was the best under R7B3. Ventilation resulted in more rapid apical shoot growth and rooting compared with control plants, when both were treated with the R7B3 system. We demonstrated here that plant growth can be controlled by using LEDs to adjust for the most effective irradiation conditions, compared with the performance observed when conventional fluorescent lamps are utilized.