UASB+MBR+NF处理焚烧垃圾渗滤液的设计及运行

介绍了UASB+MBR+NF工艺处理某垃圾焚烧厂渗滤液的工艺流程、构筑物设计参数及运行情况。运行结果表明,该工艺对垃圾渗滤液具有较高的去除率,COD、BOD5、NH3-N、SS的去除率分别高达99.84%、99.94%、99.28%、99.83%。处理后出水的各项指标可以达到《污水综合排放标准》(GB 8978—1996)中的一级排放标准。采用该工艺去除1 kg COD需要花费0.57元。与城市污水厂生活污水的运行费用相比,该工艺具有较好的经济性。     

Sludge Dewatering and Aggregate Formation Effects through Taylor Vortex Assisted Flocculation

Abstract

For polymer induced flocculation processes, the effects of flow patterns in a gap of a conical stirrer on aggregate formation and subsequent sludge dewatering efficiency were analysed. Different flow regimes were identified by lab scale investigations with model substances and summarized in a Ta and Re number plane. An enhancement of sludge dewaterability for polymer induced flocculation processes was identified through post‐treatment of flocculated sludge aggregates by the specific flow pattern of stable and wavy Taylor vortices. Photo‐optical image analysis of flocculated aggregates shows a clear change of aggregate size distribution with less small particles during aggregate forming by Taylor vortices compared to classical flocculation procedure by stirrer. Results from technical scale dewatering analyses confirmed enhancement of sludge dewatering efficiency for six different dewatering machines using the identified wavy and stable Taylor vortex flow pattern regime.     

Study on the nitrogen transformation during the primary pyrolysis of sewage sludge by Py-GC/MS and Py-FTIR

The nitrogen transformation with attention to the intermediates and NO_x precursors has been investigated during the primary pyrolysis of sewage sludge by using Pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) and Pyrolyzer-Fourier transform infrared spectrometry (Py-FTIR). A three-stage process of nitrogen transformation during the sewage sludge pyrolysis was suggested. The decomposition of labile protein and inorganic ammonium salt mainly occurred in the first stage (<300 °C), giving rise to a small amount of NH₃. In the second stage (300–600 °C), the macromolecular protein firstly cracked into small molecular amine compounds, and then went through deamination process, contributed to a large release of NH₃. In the third stage (600–900 °C), the amine compounds converted into nitriles, and generated a large amount of HCN, while the formation of NH₃ slowed down accordingly.     

Bioaugmentation with Thermoanaerobacterium thermosaccharolyticum W16 to enhance thermophilic hydrogen production using corn stover hydrolysate

In the present work, with corn stover hydrolysate as the substrate, an efficient hydrogen-producing thermophile, Thermoanaerobacterium thermosaccharolyticum W16, was added to three kinds of seed sludge (rotten corn stover (RCS), cow dung compost (CDC), and sludge from anaerobic digestion (SAD)) to investigate the effect of bioaugmentation on thermophilic hydrogen production. Batch test results indicate that the bioaugmentation with a small amount of the strain T. thermosaccharolyticum W16 (5% of total microbes) increased the hydrogen yield to varying degrees (RCS: from 8.78 to 9.90 mmol H₂/g utilized sugar; CDC: from 8.18 to 8.42 mmol H₂/g utilized sugar; SAD: from 8.55 to 9.17 mmol H₂/g utilized sugar). The bioaugmentation process also influenced the soluble metabolites composition towards more acetate and less butyrate production for RCS, and more acetate and less ethanol accumulation for SAD. Microbial community analysis indicates that Thermoanaerobacterium spp. and Clostridium spp. dominated microbial community in all situations and might be mainly responsible for thermophilic hydrogen generation. For RCS and SAD, the bioaugmentation obviously increased the relative abundance of the strain T. thermosaccharolyticum W16 in microbial community, which might be the main reason for the improvement of hydrogen production in these cases.     

Carboxymethyl sago pulp/chitosan hydrogel as an immobilization medium for activated sludge for p-nitrophenol biodegradation

In this study, carboxymethyl sago pulp (CMSP) derived from sago waste was successfully crosslinked with ferric ions in the presence of chitosan forming a novel immobilization matrix for p-nitrophenol (PNP)-acclimated activated sludge. On the basis of the shortest biodegradation time of PNP, the optimized operational conditions of immobilization were found to be: 7 w/v% CMSP, 9 g L⁻¹ of activated sludge, 0.1 M ferric ion, and 15 min of crosslinking time. Observable inhibited PNP biodegradation was exhibited by the suspended activated sludge at the initial PNP concentration of 400 mg L⁻¹. In contrast, complete mineralization was achieved by the CMSP/chitosan-immobilized activated sludge (CMSP/Ch-AS) beads. The results revealed the important role of CMSP/Ch hydrogel in protecting activated sludge from the toxicity of PNP. The CMSP/Ch-AS beads could be reused consecutively up to three and two cycles, respectively, for the biodegradation of PNP at 200 and 400 mg L⁻¹, with the attainment of more than 99% of PNP removal at each cycle. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47531.     

Co-fermentation of sewage sludge and algae and Fe2+ addition for enhancing hydrogen production

Co-fermentation of sewage sludge and algae was performed for enhancing the hydrogen production, and the effect of Fe²⁺ on co-fermentation process was examined. Results showed that both co-fermentation process and Fe²⁺ addition promoted hydrogen production. Highest hydrogen production of 28 mL/100 mL (14.8 mL H₂/g VS_added) was obtained from the co-fermentation group with 600 mg/L Fe²⁺ addition, which was 2.15 times, 2.00 times and 1.87 times of mono-fermentation of sludge, mono-fermentation of algae, and the co-fermentation group without Fe²⁺ addition. Both volatile solids and protein degradation were stimulated by co-fermentation process. Microbial analysis showed that co-fermentation groups with Fe²⁺ addition enriched Clostridium sensu stricto 13, Clostridium tertium and Terrisporobacter, which were positively correlated with cumulative hydrogen production. This study suggested that the co-fermentation of sludge and algae in the presence of Fe²⁺ could significantly improve the hydrogen production by stimulating the hydrogen-producing metabolism.     

Biotechnological potential of industrial wastes for economical citric acid bioproduction by Aspergillus niger through submerged fermentation

Submerged citric acid (CA) bioproduction was carried out by Aspergillus niger NRRL‐567 using various industrial wastes, such as brewery spent liquid (BSL), lactoserum and starch industry water sludge. CA bioproduction was carried out by varying the temperature (25–35 °C), pH (3–5), addition of inducers, incubation time and supplementation with different proportions of apple pomace ultrafiltration sludge (APS). The results indicated that under the best conditions with 3% (v/v) methanol, the optimal concentration of 11.34 g L^?1 CA was recorded using BSL at pH 3.5 and temperature 30 °C after 120‐h incubation period. Supplementation of methanol resulted in an increase of 56% CA production. Meanwhile, under similar conditions, higher concentration of 18.34 g L^?1 CA was reported with the supplementation of BSL with 40% (v/v) APS having suspended solids concentration of 30 g L^?1. The present study demonstrated the potential of BSL supplemented with APS as an alternative cheap substrate for CA fermentation.     

Production of bio‐energy from organic waste: effect of temperature and substrate composition

This article presents the influence of temperature and influent substrate composition on the produced biogas volume in an anaerobic co‐digestion process. Four cases of anaerobic digestion were considered. Digestion of waste sludge only and anaerobic co‐digestion of sludge mixed with solid waste in mesophilic (T = 35 °C) and thermophilic (T = 55 °C) phases. The obtained results show that thermophilic co‐digestion gives the best results; although the temperature has an effect on biogas production, it remains however quite relative compared to the effect of solid waste. They confirm, surely, that the combined effect of temperature and solid waste improves considerably the biogas production rate (GPR). Changing conditions from mesophilic to thermophilic ones for waste sludge alone and for waste sludge mixed with solid waste results in an increase of the GPR from 0.18 to 0.39 m³/m³.d and from 0.29 to 0.96 m³/m³.d, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

Reduction in nitrogen oxides emissions by MILD combustion of dried sludge

Demands for the thermal treatment of sewage sludge are increasing due to the regulation of its ocean disposal and the desire to recover its potential energy. Because of the high nitrogen content in sewage sludge, one of the concerns about its combustion is a potential increase in NO_x emissions. Although a number of studies have been conducted to reduce NO_x emissions by combustion modifications, very few studies have addressed the combustion of dried sludge. In this study, a combustion technique called moderate or intense low oxygen dilution (MILD) was applied to the combustion of dried sludge with the goal of reducing NO_x emissions. MILD combustion of dried sludge was tested using both our laboratory-scale vertical combustor with internal circulation and our horizontal cyclone combustor with external circulation. Tests were conducted to find suitable operating conditions and to demonstrate the stable MILD combustion of dried sludge. From these tests, fuel and air flow patterns were found to be an important factor in maintaining stable MILD combustion, and the horizontal cyclone combustor demonstrated excellent performance in the reduction of NO_x emissions by the MILD combustion of dried sludge.