Effect of pre-treatments on hydrolysis and methane production potentials of by-products from meat-processing industry

In this study, the effect of five pre-treatments (thermal, ultrasound, acid, base and bacterial product) on hydrolysis and methane production potentials of four by-products from meat-processing industry was studied. The bacterial product Liquid Certizyme 5™ increased soluble chemical oxygen demand (CODsol) of digestive tract content and drumsieve waste the most as compared to untreated material (62 and 96%, respectively), while ultrasound was the most effective to increase CODsol with dissolved air flotation (DAF) sludge (88%) and grease trap sludge (188%). In batch experiments, thermal treatment increased methane production potential of drumsieve waste, acid of grease trap sludge and all pre-treatments of DAF sludge. However, with all other pre-treatments, methane production potential was decreased compared to untreated materials, apparently due to inhibition by hydrolysis products and/or possible re-crystallization of some compounds. Methane production potentials from the untreated materials were as follows: digestive tract content 400 ± 50 m³ CH₄/t volatile solids (VS)_added, drumsieve waste 230 ± 20 m³ CH₄/tVS_added, DAF sludge 340 ± 17 m³ CH₄/tVS_added and grease trap sludge 900 ± 44 m³ CH₄/tVS_added.     

Treatment of Terasil Red R Dye Wastewater using H2O2/pyridine/Cu(II) System

The H₂O₂/pyridine/Cu(II) advanced oxidation system was used to assess the efficiency of the treatment of a 1 g L⁻¹ Terasil Red R dye solution. This system was found to be capable in reducing the concentration of chemical oxygen demand (COD) of the dye solution up to 90%, and achieving 99% in decolorization at the optimal concentration of 5.5 mM H₂O₂, 38 mM pyridine and 1.68 mM Cu(II). The final concentration of COD was recorded at 117 mg L⁻¹ and color point at 320 PtCo. Full 2⁴ factorial design and the response surface methodology using central composite design (CCD) were utilized in the screening and optimization of this study. Treatment efficiency was found to be pH independent. The amount of sludge generation was in the range of 100–175 mg L⁻¹ and the sludge produced at the optimal concentration was 170 mg L⁻¹.     

The acceleration of sludge granulation using the chlamydospores of Phanerochaete sp. HSD

In the present paper, a novel method to accelerate sludge granulation is presented. Inoculation with chlamydospores of Phanerochaete sp. HSD accelerated sludge granulation during the treatment process of phenol wastewater, and the sludge granulation rate reached 66 ± 2% on day 7, 32 days earlier than that of the control inoculated with activated sludge only. Aerobic granule in R1 (AG_R1) showed an annual ring-like multilayer structure and a primary core also existed in the nuclear area of the granule. The mechanism of rapid granulation revealed that the chlamydospore could survive in phenol wastewater and form the primary matrix on which aerobic granule was developed layer by layer. In addition, AG_R1 developed in a phenol uptake system to counteract the adverse effects of phenol inhibition. Higher tolerance toward wastewater with high phenol strength was exhibited, and the maximum specific phenol degradation rate reached 1.54 g phenol g⁻¹ VSS day⁻¹.     

Treatment of anaerobic sludge digester effluents by the CANON process in an air pulsing SBR

The CANON (Completely Autotrophic Nitrogen removal Over Nitrite) process was successfully developed in an air pulsing reactor type SBR fed with the supernatant from an anaerobic sludge digester and operated at moderately low temperatures (18–24 °C). The SBR was started up as a nitrifying reactor, lowering progressively the dissolved oxygen concentration until reaching partial nitrification. Afterwards, an inoculation with sludge containing Anammox biomass was carried out. Nitrogen volumetric removal rates of 0.25 g N L⁻¹ d⁻¹ due to Anammox activity were measured 35 d after inoculation even though the inoculum constituted only 8% (w/w) of the biomass present in the reactor and it was poorly enriched in Anammox bacteria. The maximal nitrogen removal rate was of 0.45 g N L⁻¹ d⁻¹. By working at a dissolved oxygen concentration of 0.5 mg L⁻¹ in the bulk liquid, nitrogen removal percentages up to 85% were achieved.     

Emissions of polycyclic aromatic hydrocarbons from fluidized and fixed bed incinerators disposing petrochemical industrial biological sludge

This study investigated the emissions of polycyclic aromatic hydrocarbons (PAHs) from two fluidized bed incinerators (FLBI_A and FLBI_B) and one fixed bed incinerator (FIBI) disposing biological sludge generated from the petrochemical industries in Taiwan. The results of 21 individual PAHs (including low (LM-PAHs), middle (MM-PAHs) and high molecular weight PAHs (HM-PAHs)) were reported. The LM-PAHs mainly dominated the total-PAHs in the stack flue gases, whereas the LM- and HM-PAHs dominated the total-PAHs in the bottom fly, fly ash and WSB effluent. Due to high carcinogenic potencies (= total-BaP_eq concentrations) in the bottom ash (195 ng g⁻¹) and WSB effluent (20,600 ng L⁻¹) of the FIBI, cautious should be taken in treating them to avoid second contamination. Lower combustion efficiency and elevated fuel/feedstock (F/W) ratio for the FIBI led to the highest total emission factor of total-PAHs (38,400 μg kg⁻¹). Lower total-PAH removal efficiencies of wet scrubber (WSB) (0.837–5.89%), cyclone (0.109–0.255%) and electrostatic precipitator (ESP) (0.032%) than those reported elsewhere resulted in high fraction in PAH contributions from the stack flue gases. Lower total-PAH emission factor was found for FLBI_A (2380 μg kg⁻¹ biological sludge) with higher combustion efficiency compared to those for FLBI_B (11,500 μg kg⁻¹) and FIBI (38,400 μg kg⁻¹ biological sludge), implying that combustion efficiency plays a vital role in PAH emissions.     

Enhancing simultaneous electricity production and reduction of sewage sludge in two-chamber MFC by aerobic sludge digestion and sludge pretreatments

Batch tests were conducted to enhancing simultaneous electricity production and reduction of sewage sludge in two-chamber MFC by aerobic sludge digestion in cathode chamber and sludge pretreatments (sterilization and base pretreatment) prior to sludge addition to anode chamber, respectively. During the stable stage, The voltage outputs and power densities of MFC increased from 0.28-0.31 V to 17.3-21.2 mW/m(2) to 0.41-0.43 V and 36.8-40.1 mW/m(2), respectively, when aerobic sludge digestion occurred in the cathode chamber. When the sludge added to the anode chamber was sterilized or base pretreated, the voltage outputs and power densities of MFC increased from 0.30-0.32 V and 19.9-22.6 mW/m(2) (raw sludge) to 0.34-0.36 V and 25.5-28.6 mW/m(2) (sterilized sludge), 0.41-0.43 V and 37.1-40.8 mW/m(2) (base pretreated sludge), respectively. At the end of the test, the total suspended solids (TSS) and volatile suspended solids (VSS) reduction of sludge in the anode chambers increased from 33.9% and 36.8% to 34.5% and 38.7% with aerobic sludge digestion in the cathode chamber, respectively; while, those (TSS and VSS reduction) with sludge pretreatments prior to the sludge addition to the anode chambers increased from 25.1% and 22.8% (raw sludge) to 32.8% and 34.6% (sterilized sludge), and 25.5% and 26.7% (base pretreated sludge), respectively. The experimental results illuminated both aerobic sludge digestion in the cathode chamber and sludge pretreatments (sterilization and base pretreatment) prior to sludge addition to the anode chamber could enhance simultaneous electricity production from sludge and sludge reduction.     

Feasibility of nutrient recovery from industrial sludge by vermicomposting technology

Transformation of industrial sludges into vermicompost is of double interest: on the one hand, a waste is converted into value added product, and, on the other, it controls a pollutant that is a consequence of increasing industrialization. This paper reports the feasibility of utilization of vermicomposting technology for nutrient recovery from industrial sludge in laboratory scale experiment employing Eisenia fetida earthworm. A total of nine vermireactors, having different percentage of wastewater treatment plant sludge of a food industry and cow dung, were established and monitored for fertilizer quality of vermicompost and growth and fecundity of the earthworms for 3 months. The earthworms were unable to survive in 100% FIS. There was a decrease in pH, organic carbon content, organic matter, C:N ratio, and increase in ash content, EC, nitrogen, potassium and phosphorus content in all the vermireactors. Total Kjeldhal nitrogen (TKN) content increased in the range of 12.2–28.7 g kg⁻¹ in different vermireactors after vermicomposting. C:N ratio was 1.59–5.24 folds lesser in final vermicomposts than initial raw substrate. The heavy metals’ content in final vermicomposts was higher than initial feed mixtures. Maximum worm biomass was observed in control, i.e., 100% CD (836 mg earthworm⁻¹) and the lowest in 30% CD + 70% FIS feed mixture (280 mg earthworm⁻¹). Cocoon production was started during 6–7th week in all feed mixture except in feed mixture no. 9. After 12 weeks maximum cocoons (57) were counted in 100% CD and minimum (2) in 30% CD + 70% FIS feed. The results indicated that food industry sludge could be converted into good quality manure by vermicomposting if mixed up to 30% with cow dung.     

Reduction of excess sludge production in sequencing batch reactor through incorporation of chlorine dioxide oxidation

In this study, chlorine dioxide (ClO₂) instead of chlorine (Cl₂) was proposed to minimize the formation of chlorine-based by-products and was incorporated into a sequencing batch reactor (SBR) for excess sludge reduction. The results showed that the sludge disintegrability of ClO₂ was excellent. The waste activated sludge at an initial concentration of 15 g MLSS/L was rapidly reduced by 36% using ClO₂ doses of 10 mg ClO₂/g dry sludge which was much lower than that obtained using Cl₂ based on similar sludge reduction efficiency. Maximum sludge disintegration was achieved at 10 mg ClO₂/g dry sludge for 40 min. ClO₂ oxidation can be successfully incorporated into a SBR for excess sludge reduction without significantly harming the bioreactor performance. The incorporation of ClO₂ oxidation resulted in a 58% reduction in excess sludge production, and the quality of the effluent was not significantly affected.     

Production of biogas from municipal solid waste with domestic sewage

In this study, experiments were conducted to investigate the production of biogas from municipal solid waste (MSW) and domestic sewage by using anaerobic digestion process. The batch type of reactor was operated at room temperature varying from 26 to 36 degrees C with a fixed hydraulic retention time (HRT) of 25 days. The digester was operated at different organic feeding rates of 0.5, 1.0, 2.3, 2.9, 3.5 and 4.3kg of volatile solids (VS)/m(3) of digester slurry per day. Biogas generation was enhanced by the addition of domestic sewage to MSW. The maximum biogas production of 0.36m(3)/kg of VS added per day occurred at the optimum organic feeding rate of 2.9kg of VS/m(3)/day. The maximum reduction of total solids (TS) (87.6%), VS (88.1%) and chemical oxygen demand (COD) (89.3%) occurred at the optimum organic loading rate of 2.9kg of VS/m(3)/day. The quality of biogas produced during anaerobic digestion process was 68-72%.     

Vapor phase growth and optical properties of single-crystalline SnO2 nanobelts

Mass production of single-crystalline SnO₂ nanobelts was successfully achieved through a thermal evaporation of metallic Sn powders at 900 °C. The as-prepared SnO₂ nanobelts were typically 30-200 nm in width, 10-50 nm in thickness, and about tens of micrometers in length. In addition to the classical Raman models, two new Raman bands at 498 and 698 cm⁻¹ are observed for rutile-phased SnO₂ nanobelts, which can be attributed to the IR-active A_2u TO and A_2u LO modes, respectively. Photoluminescence (PL) spectrum of SnO₂ nanobelts featured an emission band at 615 nm (with a small shoulder at 585 nm), which might correspond to the existence of oxygen deficiencies in the produced belts. The formation of SnO₂ nanobelts followed a vapor-solid (VS) growth mechanism.     

Adsorption of copper(II) onto sewage sludge-derived materials via microwave irradiation

The materials with adsorbent properties were produced from urban sewage sludge by two different procedures via microwave irradiation: (1) by one single pyrolysis stage (SC); (2) by chemical activation with ZnCl₂ (SZ). The BET, SEM and FT-IR have been used to evaluate the pore structural parameters and surface chemistry of the adsorbents, respectively. Subsequently they were used for adsorption of Cu(II) from aqueous solutions. The effects of various experimental parameters, such as pH, temperature were investigated in a batch-adsorption technique. The results showed that the adsorption of Cu(II) was maximal at pH 5.0. The kinetic study demonstrated that the adsorption process was followed the second-order kinetic equation. The experimental adsorption isotherm data were well fitted with Langmuir model and the maximum adsorption capacity of Cu(II) were found to be 3.88 and 10.56 mg/g for SC and SZ, respectively, in the solution of pH 5.0. Thermodynamic parameters such as changes in the enthalpy (ΔH⁰), entropy (ΔS⁰) and free energy (ΔG⁰) indicate that Cu(II) adsorption onto SC and SZ is an endothermic and spontaneous process in nature at 15-45 °C. These results indicate that the sewage sludge-derived material via microwave induced ZnCl₂ activation is an effective and alternative adsorbent for the removal of Cu(II) from aqueous solution.     

Fluoride removal performance of glass derived hydroxyapatite

A novel sodium calcium borate glass derived hydroxyapatite (G-HAP) with different ranges of particle size was prepared by immersion sodium calcium borate glass in 0.1 M K₂HPO₄ solution by the ratio of 50 g L⁻¹ for 7 days. The unique advantage of G-HAP for the adsorption of fluoride ions in solutions was studied. The effects of size and quantity of particles, pH value and adsorption time on adsorption performance were investigated. The maximum adsorption capacity was 17.34 mg g⁻¹ if 5 g L⁻¹, <100 μm G-HAP was added to a solution with an initial pH value of 6.72 and the adsorption time was 12 h. The results showed that the micro-G-HAP could immobilize F⁻ in solution more effectively than commercial nano-HAP, which makes potential application of the G-HAP in removing the fluoride ions from wastewater. The adsorption kinetics and isotherms for F⁻ could be well fitted by a second order kinetic model and Freundlich isotherm model respectively, which could be used to describe the adsorption behavior. The mechanism of G-HAP in immobilizing F⁻ from aqueous solutions was investigated by the X-ray diffraction (XRD), infrared spectra (IR) and scanning electron microscopy (SEM).     

Study on the homogeneity of hydrogenation for LaFe11.5Si1.5 intermetallic compound

The homogeneity of hydrogen absorption for LaFe_11.5Si_1.5 intermetallic compound was investigated. The hydrides remained NaZn₁₃-type structure when the hydrogenation temperature varied from 423 K to 923 K under 1 atm hydrogen atmosphere. The Differential Scanning calorimetric (DSC) measurements revealed slightly inhomogeneous distribution of hydrogen atoms in the hydrides hydrogenated at a low temperature. The activation before hydrogenating at a higher temperature could improve the homogeneity of hydrogen absorption. Uniform magnetic transition temperature, corresponding to the homogeneous hydrogen absorption, was observed by hydrogenating the compound at 823 K, or at 523 K after activation. The maximum magnetic entropy change ΔS_M (ΔH = 2 T) for the compound hydrogenated at 823 K is about 15.5 J/kg K with the latent heat of 5.12 × 10³ J/kg during the phase transition.     

Resorption system with simultaneous heat and cold production

A resorption system with simultaneous cold and heat production was studied. The heat produced could be used for sanitary or process purposes, or to drive another heat-powered machine. The resorption reactors had MnCl₂ and NH₄Cl as reactant (which are impregnated in expanded graphite) and NH₃ as refrigerant. The combined coefficient of performance and amplification (COPA) of this system reached 1.3 when the cooling effect was produced at 0 °C and heating effect at 75 °C with the regeneration temperature of 140 °C. Its COP was 0.35 with a specific cooling power (SCP) of 1.12 MJ kg⁻¹ day⁻¹, and the heat sink in this case remained below the cooling temperature for more than 5 h. Because of the heat production at certain temperature level (from 70 °C to 80 °C) in this study, the released heat could be used to power a silica gel-water adsorption chiller and the overall COP of the combined system would increase dramatically.     

Effect of increasing nitrobenzene loading rates on the performance of anaerobic migrating blanket reactor and sequential anaerobic migrating blanket reactor/completely stirred tank reactor system

A laboratory scale anaerobic migrating blanket reactor (AMBR) reactor was operated at nitrobenzene (NB) loading rates increasing from 3.33 to 66.67 g NB/m³ day and at a constant hydraulic retention time (HRT) of 6 days to observe the effects of increasing NB concentrations on chemical oxygen demand (COD), NB removal efficiencies, bicarbonate alkalinity, volatile fatty acid (VFA) accumulation and methane gas percentage. Moreover, the effect of an aerobic completely stirred tank reactor (CSTR) reactor, following the anaerobic reactor, on treatment efficiencies was also investigated. Approximately 91–94% COD removal efficiencies were observed up to a NB loading rate of 30.00 g/m³ day in the AMBR reactor. The COD removal efficiencies decreased from 91% to 85% at a NB loading rate of 66.67 g/m³ day. NB removal efficiencies were approximately 100% at all NB loading rates. The maximum total gas, methane gas productions and methane percentage were found to be 4.1, 2.6 l/day and 59%, respectively, at a NB loading rate of 30.00 g/m³ day. The optimum pH values were found to be between 7.2 and 8.4 for maximum methanogenesis. The total volatile fatty acid (TVFA) concentrations in the effluent were 110 and 70 mg/l in the first and second compartments at NB loading rates as high as 66.67 and 6.67 g/m³ day, respectively, while they were measured as zero in the effluent of the AMBR reactor. In this study, from 180 mg/l NB 66 mg/l aniline was produced in the anaerobic reactor while aniline was completely removed and transformed to 2 mg/l of cathechol in the aerobic CSTR reactor. Overall COD removal efficiencies were found to be 95% and 99% for NB loading rates of 3.33 and 66.67 g/m³ day in the sequential anaerobic AMBR/aerobic CSTR reactor system, respectively. The toxicity tests performed with Photobacterium phosphoreum (LCK 480, LUMIStox) and Daphnia magna showed that the toxicity decreased with anaerobic/aerobic sequential reactor system from the influent, anaerobic and to aerobic effluents.     

Design and synthesis of immunoconjugates and development of competition inhibition enzyme-linked immunosorbent assay (CIEIA) for the detection of O-isopropyl methylphosphonofluoridate (sarin): an organophosphorous toxicant

Three haptens of the organophosphorus (OP) toxicant ‘sarin’ having different spacer arm were designed and synthesized. Haptens were conjugated with BSA (bovine serum albumin) and ovalbumin (OVA) for raising antibody and coating antigen. High antibody titer with higher specificity was obtained from 4-(4-(isopropoxy(methyl)phosphoryloxy)phenylamino)-4-oxobutanoic acid (hapten B) having reasonable long spacer arm. For the standard curve, an IC₅₀ (inhibitory concentration) of free antigen was found to be 0.415 μg mL⁻¹ on the basis of indirect competitive ELISA. The study revealed that heterology in competition inhibition enzyme immunoassay (CIEIA) produced remarkable improvement in the sensitivity and specificity of the assay. Under the optimized conditions, the quantitative working range was found to be 0.19-1.56 μg mL⁻¹ with a limit of detection (LOD) of 0.05 μg mL⁻¹. The antibodies showed negligible cross reactivity (CR) with other OP toxicants and pesticides, which makes the assay suitable for the selective detection of sarin.     

Microwave enhanced Fenton-like process for the treatment of high concentration pharmaceutical wastewater

This paper explored a novel process for wastewater treatment, i.e. microwave enhanced Fenton-like process. This novel process was introduced to treat high concentration pharmaceutical wastewater with initial COD loading of 49,912.5 mg L⁻¹. Operating parameters were investigated and the optimal condition included as follows: microwave power was 300 W, radiation time was 6 min, initial pH was 4.42, H₂O₂ dosage was 1300 mg L⁻¹ and Fe₂(SO₄)₃ dosage was 4900 mg L⁻¹, respectively. Within the present experimental condition used, the COD removal and UV₂₅₄ removal reached to 57.53% and 55.06%, respectively, and BOD₅/COD was enhanced from 0.165 to 0.470. The variation of molecular weight distribution indicated that both macromolecular substances and micromolecular substances were eliminated quite well. The structure of flocs revealed that one ferric hydrated ion seemed to connect with another ferric hydrated ion and/or organic compound molecule to form large-scale particles by means of van der waals force and/or hydrogen bond. Subsequently, these particles aggregated to form flocs and settled down. Comparing with traditional Fenton-like reaction and conventional heating assisted Fenton-like reaction, microwave enhanced Fenton-like process displayed superior treatment efficiency. Microwave was in favor of improving the degradation efficiency, the settling quality of sludge, as well as reducing the yield of sludge and enhancing the biodegradability of effluent. Microwave enhanced Fenton-like process is believed to be a promising treatment technology for high concentration and biorefractory wastewater.     

Prepared bed bioremediation of oily sludge in an oilfield in northern China

Field-scale bioremediation of oily sludge in prepared beds was studied at Shengli oilfield in northern China. The influence of manure, coarse sand, sawdust, a specialized microbial preparation and greenhouse conditions on the efficiency of removal of oil and grease was evaluated. After bioremediation for 230 d, oil and grease content fell by 32–42 g kg⁻¹ dry sludge in treated plots, indicating removal of 27–46% compared with only 15% in the control plot. Addition of manure, coarse sand, sawdust and greenhouse conditions significantly (p < 0.05) increased the amount removed. Moreover, the physico-chemical properties of the sludge in all treated plots improved significantly after bioremediation. Microbial biomass in sludge and community-level physiological profiling examined using BIOLOG microplates was also studied. Total petroleum hydrocarbon degraders and polycyclic aromatic hydrocarbon degraders increased in all treated oily sludge. The activity of sludge microbial communities increased markedly in the treated plots compared with the control. Canonical correspondence analysis showed that differences in substrate utilization patterns were highly correlated (p < 0.05) with sludge hydrolyzable N and oil and grease content. The biological toxicity of the oily sludge was lower following bioremediation in most of the treated plots as evaluated using Photobacterium phosphoreum T3.     

Hydrogen etching of Si3N4 layers with plasma assisted hot wire CVD

In order to develop sustainable processes for clean manufacturing environment for thin film or other solar cell production, we studied the hydrogen etching of silicon nitride (Si₃N₄) films on flat crystalline silicon (c-Silicon) substrates. With an arrangement primarily constructed for hot wire CVD (HWCVD) deposition of thin silicon films also cleaning processes with atomic hydrogen were studied with a simplified three wire assembly. The three filaments could be biased independently by different potential. A variation of hydrogen pressure and flow was performed to find out conditions of high etching rates for the Si₃N₄ layers. The etching rate was simply determined by measuring the time for total removal of the film, since this could be easily detected by the change of the anti-reflection property. Etching rates of 0.1 nm/s have been obtained under 15 Pa and a flow of 50 sccm. An intensive study was carried out of the direct current (DC) plasma hot wire CVD conditions.     

Hydrogen absorption/desorption properties of Li–Al–N–H composite

Li₃AlH₆ and LiNH₂ at a 1:3 molar ratio were mechanically milled to yield a Li–Al–N–H composite. The hydrogen storage properties of the composite were studied using thermogravimetry, differential scanning calorimetry, mass spectrometry, and X-ray diffraction. Addition of LiNH₂ lowered the decomposition temperature of Li₃AlH₆. The Li–Al–N–H composite began to release hydrogen at around 110 °C, which was 90 °C lower than the initial desorption temperature of Li₃AlH₆. About 7.46 wt% of hydrogen was released from the composite after heating from room temperature to 500 °C. A total hydrogen desorption capacity of 8.15 wt% was obtained after accounting for hydrogen released in the ball-milling process. The resulting dehydrogenated composite absorbed 3.56 wt% of hydrogen at 400 °C under a hydrogen pressure of 110 bar. The hydrogen absorption capacity and kinetic properties of the Li–Al–N–H composite significantly improved when CeF₃ was added to the composite. A maximum hydrogen absorption capacity of 4.8 wt% was reached when the composite was doped with 2 mol% CeF₃.