Combined sodium hydroxide and ammonium hydroxide pretreatment of post-biogas digestion dairy manure fiber for cost effective cellulosic bioethanol production

Influence of Sequential Liquid Ammonia and Caustic Mercerization Pre-Treatment on Dyeing Performance of Knit Cotton Fabric

A two-stage sequential pretreatment including caustic mercerization (CM) and liquid ammonia (LA) treatment was applied to investigate the influence on dyeing performance and handle of knit cotton fabric, and the relationship between dye size and dyeing properties. Various techniques were applied to characterize all the treated fabrics. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses of the treated fabrics confirmed that both sequential treatments decreased the crystallinity of cotton fabric more than only the CM or LA treatment. The pattern of cellulose I was transferred to a mixed configuration of cellulose II and cellulose III after the CM/LA or LA/CM treatment. Thermal performances measured by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) techniques showed that the thermal stability of the treated cotton only marginally decreased. The wicking height increased after the sequential CM/LA treatment, indicating that the hydrophilicity of the fabric increased. The dye absorption and color uniformity were better for the reactive dye with a smaller molecular weight (Reactive Red 2) compared with the one with a larger molecular weight (Reactive Red 195). The total dye fixation efficiency (T%) increased to 72.93% and 73.24% for Reactive Red 2 dyeings of CM/LA- and LA/CM-cotton fabric from 46.75% of the untreated fabric, respectively; the T% increased to 65.33% and 72.27% for Reactive Red 195 dyeings of CM/LA- and LA/CM-cotton fabric from 35.17% of the untreated fabric, respectively. The colorfastness and dye exhaustion and fixation percentages of the samples were enhanced after the treatments. Furthermore, compared to the single CM or LA treatment, the softness handle properties were further improved after the fabrics were sequentially treated by CM/LA. The developed pre-treatment of CM/LA can be used in the textile industry to promote the dyeability, handle, and mechanical properties of knit cotton fabrics.

Different effects of ozone and aqueous ammonia in a combined pretreatment method on rice straw and dairy manure fiber for enhancing biomethane production

Low digestibility of lignocellulosic feedstock is the most important limitation for biogas production. The synergistic effects of ozone and aqueous ammonia (OSAA) on different types of lignocelluloses including rice straw and dairy manure fiber were investigated. OSAA significantly increased biogas production of rice straw by 114.2%-172.8% when compared with using ozonation alone, while increased by 6.2%-8.8% with manure fiber. OSAA pretreatment increased biogas production of manure fiber by 55.3%-103.6% when compared with soaking aqueous ammonia (SAA) alone, while by 28.8%-39.9% with rice straw. The specific effects of pretreatment time on anaerobic digestion of manure fiber differed noticeably from those on rice straw. Ozonation time had a major function for pretreatment of manure fiber via the OSAA process, but SAA pretreatment time was more important than that for rice straw.

Thermo-chemical pretreatment of rice straw for further processing for levulinic acid production

A variety of pretreatment protocols for rice straw fiber reconstruction were evaluated under mild conditions (upto 0.2%wt. and 121°C) with the object of improving polymer susceptibility to chemical attack while preserving carbohydrate sugars for levulinic acid (LA) production. Each of the protocols tested significantly enhanced pretreatment recoveries of carbohydrate sugars and lignin, and a NaOH protocol showed the most promise, with enhanced carbohydrate preservation (upto 20% relative to the other protocols) and more effective lignin dissolution (upto 60%). Consequently, post-pretreatment fibers were evaluated for LA preparation using an existing co-solvent system consisting of HCl and THF, in addition supplementation of DMSO was attempted, in order to improve final product recovery. In contrast to pretreatment response, H2SO4 protocol fibers yielded highest LA conc. (21%wt. with 36% carbohydrate conversion efficiency) under the modest reaction conditions. Apparent spectroscopic analysis witnessed for fiber destruction and delocalization of inherent constituents during pretreatment protocols.

Improving methane production from digested manure biofibers by mechanical and thermal alkaline pretreatment

Animal manure digestion is associated with limited methane production, due to the high content in fibers, which are hardly degradable lignocellulosic compounds. In this study, different mechanical and thermal alkaline pretreatment methods were applied to partially degradable fibers, separated from the effluent stream of biogas reactors. Batch and continuous experiments were conducted to evaluate the efficiency of these pretreatments. In batch experiments, the mechanical pretreatment improved the degradability up to 45%. Even higher efficiency was shown by applying thermal alkaline pretreatments, enhancing fibers degradability by more than 4-fold. In continuous experiments, the thermal alkaline pretreatment, using 6% NaOH at 55°C was proven to be the most efficient pretreatment method as the methane production was increased by 26%. The findings demonstrated that the methane production of the biogas plants can be increased by further exploiting the fraction of the digested manure fibers which are discarded in the post-storage tank.

Physico-chemical pretreatment and fungal biotreatment for park wastes and cattle dung for biogas production

With the rising demand for renewable energy and environmental protection, anaerobic digestion of biogas technology has attracted considerable attention within the scientific community. The effect of physico-chemical pretreatment on cellulose degradation followed by fungal treatment by Aspergillus terreus and Trichoderma viride to treat cellulosic biomass for enhancing its digestibility was investigated. The tested substrate was digested with and without physical, chemical, and biological treatment. Fresh leaves, dry leaves and cattle dung were characterized by a total solids content 35, 84 and 17 %, volatile solids content 81.2, 59.49 and 64.5 % and C/N ratio 31, 45.4 and 13.6, respectively. Biogas total volume was determined using water replacement technique, while methane volume was determined using precipitation of CO₂ in 20 % NaOH solution. Pretreatment steps were carried out by using mechanical and chemical pretreatments using 2.5 % NaOH mixed with 2.5 % NH₄OH for 15 days, followed by biological treatment of A. terreus and T. viride. The potential of pretreatment of substrate was studied at regular intervals of 0, 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 days determining the change in chemical and physical compositions of used substrates. Biogas production was 102.6 and 125.9 L/KgVS from untreated and pretreated substrate, respectively. On the other hand, methane production was 61.4 and 79.8 L/KgVS from untreated and pretreated substrate, respectively. In conclusion, Physical (milling), chemical (NaOH and NH₄OH) pretreatment in addition to fungal (A. terreus and T. viride) treatment for the tested substrate prior to AD was an efficient process for improvement of biogas and methane production.

Effect of Wood Biochar in Manure-Applied Sand Columns on Leachate Quality

Agricultural operations can pose a threat to the quality of nearby water sources particularly from nitrogen (N) and phosphorus (P) losses following land application of manure. Biochar application to soils has the potential to ameliorate degraded soils and reduce nutrient leaching to groundwater. The effects of amending sand soil columns with hybrid poplar biochar ( spp.) made by a slow-pyrolysis process at 450°C at varying rates (0, 1, 2, and 5% by weight) with repeated dairy manure applications over a 56-wk period was examined to evaluate the impact to leachate water quality. Increasing levels of biochar decreased cumulative levels of total N (TN) by 21 to 59%, nitrate (NO-N) by 17 to 46%, and ammonia (NH-N + NH-N) by 46 to 90% in leachate but increased cumulative leaching of total P (TP). Overall leachate pH was increased and peak levels of 5-d biological oxygen demand (BOD) in leachate after manure application were decreased with increasing levels of biochar amendment. The results from this study indicate that biochar amendments could be effective in reducing nitrogen leaching from soils, though further study is needed to determine practical application in a field setting.

Beyond land application: Emerging technologies for the treatment and reuse of anaerobically digested agricultural and food waste

Effective treatment and reuse of the massive quantities of agricultural and food wastes generated daily has the potential to improve the sustainability of food production systems. Anaerobic digestion (AD) is used throughout the world as a waste treatment process to convert organic waste into two main products: biogas and nutrient-rich digestate, called AD effluent. Biogas can be used as a source of renewable energy or transportation fuels, while AD effluent is traditionally applied to land as a soil amendment. However, there are economic and environmental concerns that limit widespread land application, which may lead to underutilization of AD for the treatment of agricultural and food wastes. To combat these constraints, existing and novel methods have emerged to treat or reuse AD effluent. The objective of this review is to analyze several emerging methods used for efficient treatment and reuse of AD effluent. Overall, the application of emerging technologies is limited by AD effluent composition, especially the total solid content. Some technologies, such as composting, use the solid fraction of AD effluent, while most other technologies, such as algae culture and struvite crystallization, use the liquid fraction. Therefore, dewatering of AD effluent, reuse of the liquid and solid fractions, and land application could all be combined to sustainably manage the large quantities of AD effluent produced. Issues such as pathogen regrowth and prevalence of emerging organic micro-pollutants are also discussed.