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In this study, alternative uses for lignocellulosic waste by considering them a source of eco-friendly and renewable energy generation with the application of the anaerobic digestion of treated and untreated waste for biogas and biohydrogen generation were investigated. The diluted sulfuric acid method was used for both the substrates and inoculum. Hydrogen production was absent when untreated spent coffee grounds (SCG) and alcohol waste (AW) were both used with the inoculum at pH 5.5 and pH 7.5. Meanwhile, the highest biogas yield of 320 dm3 kg V.S−1 was obtained when using AW at pH 7.5, with a 190 dm3 kg V.S−1 yield of methane. Instead, hydrogen production was observed when initially 4% (w/v) and 6% (w/v) SCG-containing hydrolysates were used as the substrates at pH 5.5, yielding 2.9 ± 0.09 dm3 kg V.S−1 and 3.85 ± 0.12 dm3 kg V.S−1, respectively. The further optimization of pretreatment technologies and pH control could lead to increased and prolonged hydrogen production. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of aqueous glycol ethylene was tested. The process lasted two cycles of 7 days, but after the second cycle, high hydrogen production occurred shift to dark fermentation. The biogas production lasted 14 days, obtaining peak values of hydrogen, and then rapidly stopped. In investigations, the following were checked: dependence of hydrogen, methane and hydrogen sulphide in the process. Mixtures of water with glycol ethylene mass ratio from 0.6 to 0.85 were substrates in experiments. The highest methane production was for water ethylene 0.7 ratio 2.85 L of methane with a yield of 178 mL of methane/g VSS (volatile suspended solids) of glycol ethylene. The optimal ratio of water and glycol ethylene was 0.85 25.5 mL of hydrogen (giving yield 1.71 mL of hydrogen/g VSS of glycol ethylene) and 1.71 mL of hydrogen sulphide emission for a 0.6 ratio. Popular polymer industry wastes, glycol ethylene, can be utilised by anaerobic digestion. [ABSTRACT FROM AUTHOR]

A model for calculating the maximal theoretical production of hydrogen from corn wastes is proposed. The model has been used to estimate the potential for hydrogen production from cereals wastes such as wheat, barley, and corn which are cultivated in Poland. The potentials for Pomorze and other regions of Poland are compared. The hydrogen produced from cereal wastes in Poland could potentially meet 47 % of national hydrogen demand. [ABSTRACT FROM AUTHOR]

In Poland lignocellulose wastes constitute about 43% of municipal waste (∼4 417 Gg). Anaerobic and/or dark fermentation are sustainable methods of lignocellulosic waste-management and contribute greatly to ever increasing demand for energy and products. This paper presents the results of the theoretical potential of methane and hydrogen yields from lignocellulosic wastes. Also, state-of-the-art methods in the field of lignocellulose fermentation as well as its development and pretreatment are discussed. The main reason for applying pretreatment is the decomposition (decrystallization) of cellulose and hemicellulose and cleavage of polymers into monomers, which may be more easily digested by bacteria in DF and AD fermentation processes. At current price levels the cheapest methods are basic and acidic pretreatments. Acidic pretreatment is very efficient (especially using sulfuric acids), solubilizing up to 80% of lignocellulose, but strong acids produce inhibitors and are highly corrosive. Alkaline pretreatment is a competitive and even more efficient (>80%) method to acidic pretreatment especially for some rigid materials that acid cannot solubilize. Oxidative pretreatment is usually expensive but can support the sacharisation process by either alkaline or acidic methods; in the case of NMMO efficiency reaching 82%. Ion-liquid pretreatment is selective (almost 100% sacharisation) but very costly and is too expensive for hydrogen production. The last methods can be profitable if some valuable by-products results. An efficient chemical pretreatment should be preceded by physical comminution e.g. mechanical which is the cheapest one. • Efficient anaerobic and/or dark fermentation of lignocellulose requires substrate pretreatment. • Acidic pretreatment -very popular and efficient but strong acids produce inhibitors and are strongly corrosive. • Designed pretreatment technique should prevent the corrosion stress. • Alkaline pretreatments are the cheapest (but polluting) while ionic and oxidants pretreatments are the most expensive. [ABSTRACT FROM AUTHOR]

The dark fermentation (DF) of organic textile (e.g. cotton) wastes is discussed in this paper. The influence of micro-aeration on hydrogen and methane production is studied. Fermentation was carried out under the following conditions: load 5 g VSS/L (Volatile Suspended Solids), the pH was varied in the range from 6.23 to 7.8; oxygen was added in small quantities. The oxygen flow rates (OFRs) were varied between 1 and 4.6 mL/h. The highest yields of methane (0.78 L/g VSS) were obtained under anaerobic conditions and neutral pH (7.54), while the production of hydrogen (1.1 mL/g VSS) peaked under an oxygen flow rate of 4.6 mL/h and a pH value of 6.4. Hydrogen and methane yield and the peak days of their production from various substrates (such as cotton waste, sour cabbage, wheat straw, and potato wastes) were compared and discussed. Cotton waste is a potential source of methane, but is substantially less efficient than potato waste. • Microaeration influence hydrogen and methane production differently. • There is an optimal oxygen flow rate for hydrogen production. • As increased microaeration leads to decreased methane production. • Cotton waste is a potential source of methane, although substantially less productive (or cost effective) than potato waste. [ABSTRACT FROM AUTHOR]

Hydrogen is an important raw material for chemical industry and feasible renewable energy carrier that could replace fossil fuels. However, the specie seldom exists in a form of pure H 2 . Therefore, to obtain hydrogen in volumes suitable to be used as a raw material it is necesary to decompose hydrogen-rich compounds. The carbohydrate-rich biomass can be an important source of hydrogen by applying the process of dark fermentation. In this paper potential ways of hydrogen production from organic wastes (biomass) by means of dark fermentation are reviewed and discussed. The bacteria used for dark fermentation are enlisted, characterized and compared. The pretreatment processes and various reactor designs are analyzed and discussed. The hydrogen separation by membrane method (which can provide the most pure hydrogen) are presented. The paper describes recent achievements in optimizing parameters, conditions and reactors used to industrialize dark fermentation. [ABSTRACT FROM AUTHOR]