As a by-product of lignocellulosic depolymerization for furfural production, furfural residue (FR) is composed of residual cellulose, lignin, humic acid, and other small amounts of materials, which have high reuse value. However, due to the limitation of furfural production scale and production technology, the treatment of FR has many problems such as high yield, concentrated stacking, strong acidity, and difficult degradation. This leads to the limited treatment methods and high treatment cost of furfural residue. At present, most of the furfural enterprises can only be piled up at will, buried in soil, or directly burned. The air, soil, and rivers are polluted and the ecological balance is destroyed. Therefore, how to deal with furfural residue reasonably needs to be solved. In this review, value-added products for furfural residue conversion are described in detail in the fields of soil culture, catalytic hydrolysis, thermal decomposition, and porous adsorption. The future studies reporting the FR to convert value-added products could find guidance from this review to achieve specific goals.

Biochemical methane potential (BMP) of anaerobic co-digestion (co-AD) feedstocks is an essential basis for optimizing ratios of materials. Given the time-consuming shortage of conventional BMP tests, a rapid estimated method was proposed for BMP of co-AD—with straw and feces as feedstocks—based on near infrared spectroscopy (NIRS) combined with chemometrics. Partial least squares with several variable selection algorithms were used for establishing calibration models. Variable selection methods were constructed by the genetic simulated annealing algorithm (GSA) combined with interval partial least squares (iPLS), synergy iPLS, backward iPLS, and competitive adaptive reweighted sampling (CARS), respectively. By comparing the modeling performances of characteristic wavelengths selected by different algorithms, it was found that the model constructed using 57 characteristic wavelengths selected by CARS-GSA had the best prediction accuracy. For the validation set, the determination coefficient, root mean square error and relative root mean square error of the CARS-GSA model were 0.984, 6.293 and 2.600, respectively. The result shows that the NIRS regression model—constructed with characteristic wavelengths, selected by CARS-GSA—can meet actual detection requirements. Based on a large number of samples collected, the method proposed in this study can realize the rapid and accurate determination of the BMP for co-AD raw materials in biogas engineering.

Acetic acid is the primary by-product generated from ethanol production by Fusarium oxysporum using glucose or xylose as a substrate. Aldehyde dehydrogenase (ALDH) is the critical enzyme in acetic acid metabolism. To decrease acetic acid yield in ethanol production, the 1509 bp DNA of aldh, encoding a 502 amino acid protein with a calculated molecular mass of 54.33 kDa and an isoelectric point of 6.21, was cloned from F. oxysporum. Sequence analysis confirmed that the screened proteins belonged to the ALDH family. A knockout vector, ∆aldh, containing positive (hygromycin resistance gene) and negative (thymidine kinase gene from the herpes simplex virus) selectable markers, was constructed. Ethanol production by the mutant (cs28pCAM-Pstal-∆aldh) in glucose- and xylose-containing media was 0.46 and 0.39 g/g, respectively, and these yields were 16.93% and 34.63% higher than those by the wild-type strain (0.393 and 0.289 g/g). Furthermore, the acetic acid yield of the mutant was 3.50 and 3.01 g/L, respectively, showing a 23.10% and 39.55% decrease compared with the wild-type strain (4.308 and 4.196 g/L). The biomass of the mutant (4.05 and 4.52 g/L) was lower than that of the wild-type strain (4.71 and 5.97 g/L). These results demonstrated the potential use of the genetically stable mutant for industrial bioethanol production.

Efficient and clean treatment of wastewater and energy recovery and utilization are important links to realize low-carbon development of oilfields. Therefore, this paper innovatively proposes a multi-energy complementary co-production heating system which fully and efficiently utilizes solar energy resources, oilfield waste heat resources, and biomass resources. At the same time, a typical dormitory building in the oil region was selected as the research object, the system equipment selection was calculated according to the relevant design specifications. On this basis, the simulation system model is established, and the evaluation index and operation control strategy suitable for the system are proposed. The energy utilization rate of the system and the economic, energy-saving, and environmental benefits of the system are simulated. The results show that, under the simulated conditions of two typical days and a heating season, the main heat load of the system is borne by the sewage source heat pump, the energy efficiency is relatively low in the cold period, and the energy-saving characteristics are not obvious. With the increase in heating temperature and anaerobic reactor volume, the energy consumption of the system also increases, and the energy efficiency ratio of each subsystem and the comprehensive energy efficiency ratio of the system gradually decrease. In addition, although the initial investment in cogeneration heating systems is high, the operating costs and environmental benefits are huge. Under the condition of maintaining 35 °C, the anaerobic reactor in the system can reduce carbon emissions by 12.15 t per year, reduce sulfur dioxide emissions by 98.4 kg, reduce dust emissions by 49.2 kg, and treat up to 2700 t of sewage per year, which has broad application prospects.

Industrial flare systems are used to manage exhaust gases released because of accidents or during normal mode production processes. Conversion of harmful and detrimental waste exhaust fuel into harmless products eliminates the exits of harmful emissions into the environment. To address the challenge of diminished combustion performance in high cross-wind environments, this study applies CFD simulations to analyze how transverse airflows affect key combustion characteristics and overall flame efficiency. The investigation seeks to understand the underlying mechanisms and mitigate the associated efficiency losses. Based on methane and air fuel, a three-dimensional flame model is built to examine the change in temperature field and carbon dioxide mass fraction contours of the flame at varying crosswind velocity, jet velocity, and crosswind angle of the flare; in addition, the mechanism of fuel stripping at crosswind velocity is determined. The study recommends that the flare system should discharge the flare gas at the end of the study, when the ambient crosswind angle exceeds a limit. The flame combustion efficiency with varying working conditions was measured. The results indicate that as the horizontal crosswind speed ( v _c ) increases from 0 m/s to 5 m/s, the flame tilts further from the vertical, its height decreases, the maximum radial width reduces, the high-temperature core shrinks, and combustion efficiency ( η _c ) decreases by 46.7 %. When the horizontal crosswind speed reaches 5 m/s, part of the fuel stream is diverted by the wind, causing the flame to become discontinuous. At horizontal crosswind velocity v _c = 5 m/s, combustibility efficiency was reduced by 92 % as jet velocity (v) was raised between 49.6 m/s and 70 m/s. The increase in jet speed does not effectively reduce the cross-wind influence on flame combustibility efficiency. With a jet velocity of 49.6 ms ⁻¹ and a cross-wind speed of 5 ms ⁻¹ , changing the cross-wind angle ( α ) to 40° resulted in a smaller angular displacement of the flame in the direction parallel (vertical) to the flow, a taller flame in the vertical direction, and a broader top width in the radial direction. The central flame area with the high temperature was increased gradually and the efficiency of the flame at the center to burn increased by 45.7 %.