Study on the existing forms and recovery efficiencies of phosphorus in biochar from excess sludge.

With the background of carbon neutrality, the resource and energy utilization of excess sludge (ES) have become the focus of future research. The pyrolysis of ES can produce biochar and enrich phosphorus (P). In this paper, the existing forms and recovery efficiencies of P in biochar from ES (BCES) were investigated. The results showed that the total phosphorus (TP) content of BCES at 850 °C was 65.1 mg/g, and the inorganic phosphorus (IP) content was 64.2 mg/g. The TP content of BCES was two times heavier than that of ES. The main ingredient of ES was quartz (SiO2), while the main phases of BCES were quartz (SiO2) and aluminum phosphate (AlPO4) at 650 -850 °C, and P mainly existed in the form of AlPO4. When the pyrolysis temperature was 800 and 850 °C, two new minerals appeared: Ca5(PO4)3OH and CaZn2(PO4)2·2H2O. Based on the conditions of a leaching time of 150 min, a H2SO4 concentration of 0.2 mol/L, a stirring rate of 220 rpm and a liquid-solid ratio of 50 mL/g, the leaching efficiency of P in BCES was found to be 100%. The pyrolysis temperature had no effect on leaching efficiencies of P; however, a higher pyrolysis temperature promoted metal leaching content.

Removal capacities and varying characteristics of substrates and microbial community structure in simultaneous sulfide and nitrate biological removal process'.

Under the background of carbon neutrality, resource and energy utilization technologies have become the focus of future research. The paper investigated the removal efficiencies and varying characteristics of substrates and microbial community structure in the simultaneous sulfide and nitrate biological removal (SSNBR) process. The results showed that the sulfide and nitrate removal loads reached 2.998 kg m-3∙d-1 and 1.011 kg m-3∙d-1 respectively when HRT was 2.4 h. The sulfide and nitrate molar ratios (S/N ratios) hardly influenced the removal efficiencies of sulfide and nitrate. However, the reaction products sulfate and nitrite concentrations in the effluent became higher as the S/N ratios decreased. Under the S/N ratio of 5:5, when the influent sulfide and nitrate concentrations were improved from 100 mg L-1 to 600 mg L-1 and from 87.5 mg L-1 to 306.25 mg L-1, respectively, the sulfide removal efficiencies were all above 99%, but the nitrate removal efficiencies reduced from 95.53% to 55.54%. Sulfide removal effect was better than nitrate. HRT had great effect on the nitrate removal efficiencies, but hardly affected the sulfide removal. When HRT was shortened from 12 h to 2.4 h, the sulfide removal efficiencies were all above 99%, while the nitrate removal efficiencies decreased from 93.14% to 77.04%. The main functional genera included Exiguobacterium, Clostridium, Bacillus, Thiobacillus and Sphingomonas, all of which had the nitrogen and sulfur removal functions.

Efficient and Controllable Preparation of Tridirectionally Anisotropic Sliding Surfaces Based on Spatial Light Modulator.

Realizing the efficient and controllable preparation of tridirectionally anisotropic sliding surfaces (TASSs) is extremely important. However, achieving efficient preparation of TASSs remains a great challenge. Using a spatial light modulator combined with an image feedback algorithm to adjust the femtosecond laser beam to multifocus array with a gradient intensity distribution is an efficient solution to achieve this target. Specifically, the two solutions of multifocus combination and focus intensity design are used to realize the efficient and controllable preparation of TASSs, and the structure and performance characterizations are carried out to prove the superiority of this method. It is believed that the proposal of this method can provide more inspiration for solving the high-efficiency processing problems of complex micro/nanostructures.

Optimization of Trepanning Patterns for Holes Ablated Using Nanosecond Pulse Laser in Al2O3 Ceramics Substrate.

Trepanning pattern is an important factor in laser hole machining, affecting both the hole quality and process efficiency. The influence of laser trepanning patterns on the hole ablating using nanosecond pulse laser in Al2O3 ceramics substrate was studied. Two laser trepanning patterns were evaluated, filled spiral trepanning and multiple rings trepanning, with the optimized laser machining parameters. In conjunction with the studies, the hole saturated taper and the saturated processing time were taken as the primary criteria for evaluation of the hole quality and the machining efficiency, respectively. Finally, the trepanning patterns were optimized aiming for the high hole quality; the process was based on the saturated hole tapers. The hole high qualities and machining efficiencies were obtained based on the saturated processing time, which was proven to have a great significance when using the nanosecond pulse laser to machine Al2O3 ceramics substrate.

Percussion Drilling of Deep Holes Using Picosecond Ultrashort Pulse Laser in Ni-Based Superalloy Coated with Ceramic Thermal Barrier Coatings.

Ni-based superalloy with ceramic thermal barrier coatings (TBCs) is a composite material, which can be used in special environments with high temperature and high pressure such as aeroengine blade. In order to improve the cooling effect of the aeroengine, it is necessary to perform multi-size and large-area holes processing on the surface of blades. As a non-contact processing method with fast processing speed, good processing quality and almost no deformation, laser processing has been one of the important processing methods for film cooling hole processing of aeroengine blades. Percussion drilling is presented using picosecond ultrashort pulse laser in order to explore processing of deep holes in Ni-based superalloy, ceramic TBCs, and ceramic TBCs/substrate multilayer material. The effects of pulses, threshold and wavelength on hole diameter have been discussed, and the experiment on the deep hole ablation with 1064 nm wavelength has been performed. By analyzing the hole size and morphological characteristics of multiple processing parameters, the variation of hole cylindricity is obtained. A high-quality hole, without spatters around the periphery of hole entrance and without recast layer on the side-wall surface, in Ni-based superalloy coated with ceramic TBCs has been drilled. This research has potential applications to blade film cooling holes.

Percussion Drilling Hole in Cu, Al, Ti, and Ni Alloys Using Ultra-Short Pulsed Laser Ablation.

Comparative study on micro-deep hole drilling by picosecond ultra-short pulse laser in four metals, including copper, aluminum alloy, titanium alloy, and nickel alloy, was presented. Destructive testing was performed to measure the depth, shape, and side-wall morphology of micro-deep holes in this study. Diameters and depths of micro-deep holes in four metals ablated using the same processing parameters were compared. The multiple thresholds of metals had been calculated. Relationships between hole dimensions and multiple thresholds (the average ablation threshold, the ablation threshold and the thermal threshold) and physical properties (for example, the heat capacity, the melting temperature, the optical penetration depth and the absorbance, etc.) of the four metals are examined. Furthermore, the surface and side-wall morphologies of the micro-deep holes in four metals were demonstrated. The influence mechanisms, especially the side-wall morphology, were discussed, such as the thresholds, conical emission, self-cleaning effect, physical properties of metals, the energy transmission, the plasma effect, thermochemical reaction, and so on.

Microdrilling of Through-Holes in Flexible Printed Circuits Using Picosecond Ultrashort Pulse Laser.

High density and high quality interconnects are necessary for the preparation of miniaturized and lightweight electronic products. Therefore, small-diameter and high-density through-holes in FPCs (Flexible Printed Circuits) are required. However, the current processing methods cannot further decrease the diameters and improve the quality of through-holes. Comparatively, ultrashort pulse laser is a good choice. In this paper, the processing technology for the microdrilling of through-holes in FPCs using a 10 ps pulse laser was systematically studied. The effects of laser parameters, including the wavelength, energy, pulses and polarization, on the drilling of through-holes were investigated. The various processing parameters were optimized and the plausible reasons were discussed. Finally, the desired small-diameter and high-density through-holes in FPCs were obtained. The experimental results showed that, through-holes with diameters of less than 10 µm and inlet interconnection pitches of 0~2 µm could be successfully drilled in FPCs using ultrashort pulse laser.