Energetic,bio-oil,biochar,and ash performances of co-pyrolysis-gasification of textile dyeing sludge and Chinese medicine residues in response to K_(2)CO_(3),atmosphere type,blend ratio,and temperature

Hazardous waste stream needs to be managed so as not to exceed stock-and rate-limited properties of its recipient ecosystems.The co-pyrolysis of Chinese medicine residue(CMR)and textile dyeing sludge(TDS)and its bio-oil,biochar,and ash quality and quantity were characterized as a function of the immersion of K_(2)CO_(3),atmosphere type,blend ratio,and temperature.Compared to the mono-pyrolysis of TDS,its co-pyrolysis performance with CMR(the comprehensive performance index(CPI))significantly improved by 33.9%in the N_(2)atmosphere and 33.2%in the CO_(2)atmosphere.The impregnation catalyzed the co-pyrolysis at 370℃,reduced its activation energy by 77.3 kJ/mol in the N_(2)atmosphere and 134.6 kJ/mol in the CO_(2)atmosphere,and enriched the degree of coke gasification by 44.25%in the CO_(2)atmosphere.The impregnation increased the decomposition rate of the co-pyrolysis by weakening the bond energy of fatty side chains and bridge bonds,its catalytic and secondary products,and its bio-oil yield by 66.19%.Its bio-oils mainly contained olefins,aromatic structural substances,and alcohols.The immersion of K_(2)CO_(3)improved the aromaticity of the copyrolytic biochars and reduced the contact between K and Si which made it convenient for Mg to react with SiO_(2)to form magnesium-silicate.The co-pyrolytic biochar surfaces mainly included-OH,-CH_(2),C=C,and Si-O-Si.The main phases in the co-pyrolytic ash included Ca_(5)(PO_(4))_(3)(OH),Al_(2)O_(3),and magnesium-silicate.

Formation of organic chloride in the treatment of textile dyeing sludge by Fenton system

In the oxidation treatment of textile dyeing sludge,the quantitative and transformation laws of organic chlorine are not clear enough.Thus,this study mainly evaluated the treatment of textile dyeing sludge by Fenton and Fenton-like system from the aspects of the influence of Cl^(-),the removal of polycyclic aromatic hydrocarbons (PAHs) and organic carbon,and the removal and formation mechanism of organic chlorine.The results showed that the organic halogen in sludge was mainly hydrophobic organic chlorine,and the content of adsorbable organic chlorine (AOCl) was 0.30 mg/g (dry sludge).In the Fenton system with pH=3,500 mg/L Cl-,30 mmol/L Fe^(2+)and 30 mmol/L H_(2)O_(2),the removal of phenanthrene was promoted by chlorine radicals (·Cl),and the AOCl in sludge solid phase increased to 0.55 mg/g (dry sludge) at 30 min.According to spectral analysis,it was found that ·Cl could chlorinate aromatic and aliphatic compounds (excluding PAHs) in solid phase at the same time,and eventually led to the accumulation of aromatic chlorides in solid phase.Strengthening the oxidation ability of Fenton system increased the formation of organic chlorines in liquid and solid phases.In weak acidity,the oxidation and desorption of superoxide anion promoted the removal and migration of PAHs and organic carbon in solid phase,and reduced the formation of total organic chlorine.The Fenton-like system dominated by nonhydroxyl radical could realize the mineralization of PAHs,organic carbon and organic chlorines instead of migration.This paper builds a basis for the selection of sludge conditioning methods.

Comparative assessment for removal of anionic dye from water by different waste-derived biochar vis a vis reusability of generated sludge

In this study,four biochars prepared from different crop residue waste i.e.sugarcane bagasse(SBB),coconut shell(CNB),paddy straw(PDB),and distilled waste of lemongrass(LGB)were evaluated for removal of Remazol Brilliant Blue R from the aqueous system.The RBBR adsorption capacities of biochar were 97-79%for SBB,99.9-99.47%for CNB,66.1-48%for PDB,and 78-68%for LGB,dominantly controlled by their aromaticity and mineral content.The Langmuir and Freundlich isotherms and pseudo-second-order kinetic models have described the chemisorption of RBBR on biochar surfaces.The thermodynamic data suggested that adsorption was spontaneous and endothermic.These biochars demonstrated excellent reusability(till four cycles with 50-61%regeneration).The purified water and biochar dye sludge demonstrated no phytotoxicity.The findings obtained in this study may provide supports for the potential of biochars for anionic dye removal from water and utilization of generated sludge for zero waste-producing technologies in the future.

Efficient treatment of azo dye containing wastewater in a hybrid acidogenic bioreactor stimulated by biocatalyzed electrolysis

In this study, a novel scaled-up hybrid acidogenic bioreactor（HAB） was designed and adopted to evaluate the performance of azo dye（acid red G, ARG） containing wastewater treatment. Principally, HAB is an acidogenic bioreactor coupled with a biocatalyzed electrolysis module. The effects of hydraulic retention time（HRT） and ARG loading rate on the performance of HAB were investigated. In addition, the influent was switched from synthetic wastewater to domestic wastewater to examine the key parameters for the application of HAB. The results showed that the introduction of the biocatalyzed electrolysis module could enhance anoxic decolorization and COD（chemical oxygen demand） removal. The combined process of HAB-CASS presented superior performance compared to a control system without biocatalyzed electrolysis（AB-CASS）. When the influent was switched to domestic wastewater, with an environment having more balanced nutrients and diverse organic matters, the ARG, COD and nitrogen removal efficiencies of HAB-CASS were further improved, reaching 73.3% ± 2.5%, 86.2% ± 3.8% and 93.5% ± 1.6% at HRT of 6 hr, respectively, which were much higher than those of AB-CASS（61.1% ± 4.7%,75.4% ± 5.0% and 82.1% ± 2.1%, respectively）. Moreover, larger TCV/TV（total cathode volume/total volume） for HAB led to higher current and ARG removal. The ARG removal efficiency and current at TCV/TV of 0.15 were 39.2% ± 3.7% and 28.30 ± 1.48 mA,respectively. They were significantly increased to 62.1% ± 2.0% and 34.55 ± 0.83 mA at TCV/TV of 0.25. These results show that HAB system could be used to effectively treat real wastewater.