Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia(2%, 4%, and 6%, dry matter) and three moisture contents(30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates(50, 65, and 80 g·L-1) to produce biogas. The results indicated that the wheat straw pretreated with 80% moisture content and 4% ammonia achieved the highest methane yield of 199.7 ml·g-1(based on per unit volatile solids loaded), with shorter digestion time(T80) of 25 days at the loading rate of 65 g·L-1compared to untreated one. The main chemical compositions of wheat straw were also analyzed. The cellulose and hemicellulose contents were decomposed by 2%-20% and 26%-42%, respectively,while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.

Effects of urea ammonia pretreatment on the batch anaerobic fermentation efficiency of corn stovers

In order to enhance the biogas production and provide nitrogen sources for the growth of microorganisms,experiments on urea ammonia pretreatment of corn stovers were implemented at(35±1)°C to investigate the effects of urea ammonia pretreatment on the batch anaerobic fermentation efficiency of corn stovers.This study assessed the effects of urea ammonia contents(2%,4%,and 6%)and moisture contents(30%,50%,70%and 90%)on the physical structures of lignocelluloses and the efficiency of biogas production from anaerobic fermentation of corn stovers.The results indicated that the methane production reached 230.31 mL/g VS(volatile solids)at pretreatment with 4%urea ammonia and 70%moisture contents for the batch anaerobic fermentation,which was 26.6%higher than that of the untreated group.The degradation rates of cellulose and hemicellulose were 66.34%and 75.47%after the anaerobic fermentation,respectively,which were about 22.6%and 20.9%higher than that of the untreated group,respectively.Thus,it was concluded that urea ammonia pretreatment can improve the efficiency of biogas production from anaerobic fermentation of corn stovers.

Wearability of Copper Ion Complex Bamboo Pulp Knitted Fabrics with Chitosan Pretreatment

Wearability is one of important factors for the textile product quality. The wearability of bamboo pulp knitted fabrics was mainly discussed which were treated with chitosan and cupper ammonia solution. Tensile and bursting properties, abrasion resistance,drapability,air permeability,moisture-penetrability and warmth retention properties of fabrics were tested to investigate the changes. The results showed that chitosan pretreatment improved the tensile and bursting strengths,abrasion resistance and moisture penetrability,but decreased the drapability and air permeability.Copper ammonia solution treatments decreased the tensile and bursting strengths,abrasion resistance and air permeability,but increased the drapability, moisture penetrability and warmth retention properties.

Use of additive and pretreatment to control odors in municipal kitchen waste during aerobic composting

The effects of adding a bulking agent and chemically pretreating municipal kitchen waste before aerobic composting were studied using a laboratory-scale system. The system used20-L reactors and each test lasted 28 days. The objective was to decrease NH3 and H2S emissions during composting. The bulking agent, dry cornstalks, was mixed with the kitchen waste to give a mixture containing 15%（wet weight） bulking agent. A combined treatment was also conducted, in which kitchen waste mixed with the bulking agent was pretreated with ferric chloride（FeC l3）. Less leachate was produced by the composted kitchen waste mixed with bulking agent than by the kitchen waste alone, when the materials had reached the required maturity. The presence of cornstalks also caused less H2 S to be emitted, but had little impact on the amount of NH3 emitted. The FeC l3 was found to act as an effective chemical flocculant,and its presence significantly decreased the amounts of NH3 and H2S emitted. Kitchen waste mixed with cornstalks and treated with FeC l3 emitted 42% less NH3 and 76% less H2 S during composting than did pure kitchen waste.

A sustainable preparation strategy for the nitrogen-doped hierarchical biochar with high surface area for the enhanced removal of organic dye

Biochar is a potential porous carbon to remove the contaminants from aquatic environments.Herein,N-doped hierarchical biochar was produced by the combined approach of ammonia torrefaction pretreatment(ATP)and alkali activation.ATP could not only incorporate N element into poplar wood,but obtain the loose structure of poplar wood.The highest surface area of N-doped hierarchical biochar was 2324.61 m^(2) g^(−1) after ammonia wet torrefaction pretreatment,which was higher than that of activation carbon(1401.82 m^(2) g^(−1))without torrefaction pretreatment,the hierarchical biochar(2111.03 m^(2) g^(−1))without ammonia atmosphere.The N-doped hierarchical biochar presented the highest adsorption capacity(564.7 mg g^(−1))of methyl orange(MO),which was 14.64-fold of that on biochar without N doping.In addition,the pseudo-second-order and Langmuir model fitted well with the adsorption kinetics and isotherms of the N-doped hierarchical biochar.The incorporation of nitrogen element could not only tune the distribution of surface electrons on biochar,but optimize the ambient condition of adsorption active sites as well.The adsorption of MO might occur on the N-/O-containing functional groups through the electrostatic interaction,theπ-πdispersion interaction,and the hydrogen bonding.The density functional theory showed that the graphitic-N and pyridinic-N were the dominant adsorption active sites.