Valorisation of Starch Wastewater by Anaerobic Fermentation

Starch production is mainly focused on feedstocks such as corn, wheat and potato in the EU, whereas cassava, rice, and other feedstocks are utilised worldwide. In starch production, a high amount of wastewater is generated, which accumulates from different process steps such as washing, steeping, starch refining, saccharification and derivatisation. Valorisation of these wastewaters can help to improve the environmental impact as well as the economics of starch production. Anaerobic fermentation is a promising approach, and this review gives an overview of the different utilisation concepts outlined in the literature and the state of the technology. Among bioenergy recovery processes, biogas technology is widely applied at the industrial scale, whereas biohydrogen production is used at the research stage. Starch wastewater can also be used for the production of bulk chemicals such as acetone, ethanol, butanol or lactic acids by anaerobic microbes.

Potato Starch Extrusion and Roasting with Apple Distillery Wastewater as a New Method for Resistant Starch Production

Potato starch was extruded and roasted with apple distillery wastewater to produce starch esters substituted with malic acid residues. The starch esterification degree was higher at the higher roasting temperatures. Starch modification contributed to its darker color, its increased resistance to the action of amylolytic enzymes, and its decreased solubility and heat of phase transition. The changes in the other starch properties examined depended on the extrusion and roasting temperatures. The process, which was conducted without a chemical agent—in this case, the process of starch extrusion and roasting with apple distillery wastewater—should be deemed a novel method for resistant starch production.

Evaluation and optimization of disc grating machine for sago starch production (Metroxylon spp.).

The production of Sago starch involving multiple processes and the grating process was the most important since the recovery of sago starch was directly affected. In order to produce a finer size of grated sago and high starch recovery, a new design of sago disc grating machine has been developed. A evaluation was performed to determine the optimum operation on the basis of the feeding rate and grating speed input on the sago disc grating machine, and the starch recovery as the output. The grated sago was dried and sieved at different sizes to analysis the size. A model equation was developed to predict the starch recovery. As the result, the optimum feeding rate was 0.1 m/min with 1500 rpm of grating speed produce 23.57% of sago starch recovery. Studies show that the feeding rate and grating speed affects the size of the grated sago produced (P<0.01) and directly affects starch recovery.

Starch Production in Chlamydomonas reinhardtii through Supraoptimal Temperature in a Pilot-Scale Photobioreactor

An increase in temperature can have a profound effect on the cell cycle and cell division in green algae, whereas growth and the synthesis of energy storage compounds are less influenced. In Chlamydomonas reinhardtii, laboratory experiments have shown that exposure to a supraoptimal temperature (39 °C) causes a complete block of nuclear and cellular division accompanied by an increased accumulation of starch. In this work we explore the potential of supraoptimal temperature as a method to promote starch production in C. reinhardtii in a pilot-scale photobioreactor. The method was successfully applied and resulted in an almost 3-fold increase in the starch content of C. reinhardtii dry matter. Moreover, a maximum starch content at the supraoptimal temperature was reached within 1–2 days, compared with 5 days for the control culture at the optimal temperature (30 °C). Therefore, supraoptimal temperature treatment promotes rapid starch accumulation and suggests a viable alternative to other starch-inducing methods, such as nutrient depletion. Nevertheless, technical challenges, such as bioreactor design and light availability within the culture, still need to be dealt with.

Molecular mechanism underlying the effect of maleic hydrazide treatment on starch accumulation in S. polyrrhiza 7498 fronds

Background Duckweed is considered a promising feedstock for bioethanol production due to its high biomass and starch production. The starch content can be promoted by plant growth regulators after the vegetative reproduction being inhibited. Maleic hydrazide (MH) has been reported to inhibit plant growth, meantime to increase biomass and starch content in some plants. However, the molecular explanation on the mechanism of MH action is still unclear. Results To know the effect and action mode of MH on the growth and starch accumulation in Spirodela polyrrhiza 7498, the plants were treated with different concentrations of MH. Our results showed a substantial inhibition of the growth in both fronds and roots, and increase in starch contents of plants after MH treatment. And with 75 µg/mL MH treatment and on the 8th day of the experiment, starch content was the highest, about 40 mg/g fresh weight, which is about 20-fold higher than the control. The I2-KI staining and TEM results confirmed that 75 µg/mL MH-treated fronds possessed more starch and big starch granules than that of the control. No significant difference for both in the photosynthetic pigment content and the chlorophyll fluorescence parameters of PII was found. Differentially expressed transcripts were analyzed in S. polyrrhiza 7498 after 75 µg/mL MH treatment. The results showed that the expression of some genes related to auxin response reaction was down-regulated; while, expression of some genes involved in carbon fixation, C4 pathway of photosynthesis, starch biosynthesis and ABA signal transduction pathway was up-regulated. Conclusion The results provide novel insights into the underlying mechanisms of growth inhibition and starch accumulation by MH treatment, and provide a selective way for the improvement of starch production in duckweed.

Industrial - agricultural symbiosis model for cassava starch production factory in Tay Ninh province

This study aims to propose an industrial-agricultural symbiosis model that applies the closed sloop eco-technical solutions for cassava starch production towards sustainable development. This study applies the AHP method to analyze nine alternatives and determines the best one based on 17 specific criteria for the typical cassava starch production plant in Tay Ninh province. The chosen model has 12 losed sloop solutions and can save about 40% groundwater, hundreds of cubic metre of water for irrigation in agriculture (to meet hundreds of hectares of crops), limit the lack of water in the dry season and water regulation from the Dau Tieng lake and reduce from 19-73% emissions from traffic,... Wastewater after Biogas is diluted in proportion for cassava is 28l wastewater/49l of clean water and the rubber tree is 8,5l of wastewater/7l of clean water and sugar-apple is 20l wastewater/20l of clean water wasto spray as a natural leaf fertilizer, limiting the use of NPK chemical fertilizers. Some indicators of wastewater after treatment show that it is suitable for use as fertilizer but suitable for nutrient development in the soil and increase nitrogen for plant development, reducing the cost of using stimulating fertilizers. In addition, production wastewater with high cyanide levels is also considered to dilute according to certain proportions as natural insecticidal drugs. These results show that industrial-agricultural symbiosis model bring great enviromental benifits for cassava starch industry and can be replicated in the future.

Vegetative Morphology and Starch Production Among Sago Plants (Metroxylon spp.) in Kepulauan Meranti District, Riau, Indonesia

Sago (Metroxylon spp.) is the world’s highest starch producer that have high productivity. Sago starch, however, is still underutilized compared to other starch. Sago can produce dry starch of 20-40 ton per ha per year. Indonesia has the largest sago area in the world with more than 90% of the world’s total sago area. Sago have high species diversity and not all of them have the same starch-producing capability. This research was conducted to gather information on the morphological characters and starch production potentials of several types of sago in Meranti Islands Regency, Riau Province, Indonesia, especially in Bandul, Mengkirau, Tanjung Peranap, and Bagan Melibur. Three different types of sago in Kepulauan Meranti Regency, Riau, has been identified, namely Beremban, Meranti and Sangka. The morphology and starch production of different types of sago vary depending on environmental conditions, including soil types. Beremban Sago collected from Bandul Village were found to have the highest starch content, therefore it has potentials to be developed for starch production in Indonesia.