[Research of moisture content variation in MSW landfill].

Using time domain reflectometry (TDR) technology, waste moisture content variation in aerobic and anaerobic landfill of MSW was monitored, in order to study its disciplinarian. The results showed that volume moisture content of waste increased with landfill time and water holding capacity of waste improved continuously. The correlation of water quantity and moisture content was positive in early aerobic landfill, but it became negative later. In anaerobic landfill, moisture content variation was caused by settlement and compression of MSW. TDR readings and waste material-based volume moisture content had a good correlation. The maximum error between them is about +/- 5% in aerobic landfill and +/- 2% in anaerobic landfill. TDR technology is applicable to measure moisture content in practical landfill engineering.

[Fluorescence characterization of leachate organic matter in 717 resin adsorption process].

Synchronous fluorescence spectroscopy and 3-dimensional excitation emission matrices spectra (3DEEM) were used to study the composition variation of dissolved organic matter (DOM) in landfill leachate in the adsorption process with 717 resin. The synchronous fluorescence spectra showed fluorescence intensities of longer wavelength went down greatly while those of shorter wavelength went up in the first 10 min, then there were little changes. 3DEEM results indicated that there were two fulvic-like fluorescence peaks, whose intensities decreased dramatically, the peak intensities ratio (I(UV)/I(Vis)) also decreased, and the blue shifts of emission wavelengths took place obviously with the time rising. It was indicated that the adsorption rate of DOM by 717 resin was fast, and the main adsorbed DOM had higher molecular weight and higher degree of complexity, which was potential to facilitate subsequent bio-treatment.

[Ultrasonic sludge disintegration and its influence on sludge microbial activity].

The changes of sludge disintegration degree, microbial activity and particle size were examined synchronously, and the relationships between the changes and the effect of ultrasonic parameters on microbial activity were also analyzed. The results show that the process of ultrasonic sludge treatment can be divided into two stages: at the first stage, sludge flocs are disrupted into small micro-floc aggregates with the diameter of 10-20 microm, the extracellular organic substances are dissolved, bacteria are dissociated from flocs, and the microbial activity is enhanced; at the second stage, the micro-floc aggregates are disintegrated further into bacteria bodies with the diameter less than 10 microm, the intracellular organic substances are released, and the microbial activity are decreased. The two stages are not entirely separated because sludge is inhomogeneity. When sludge disintegration degree is lower than 20%, sludge floc disruption is the main effect and the microbial activity can increase over 20%; when sludge disintegration degree is between 20%-40%, some bacteria are hurt and the microbial activity can increase by less than 20%; when sludge disintegration degree is over 40%, most bacteria are damaged and sludge activity would decrease quickly. Because low energy ultrasonic can disrupt sludge floc with no damage to microorganism in a long treatment duration time, it is suitable to stimulate sludge microbial activity.

[Effect of additive and washing pre-treatment on heavy metal vaporization during sintering process of MSWI fly ash].

An experimental work was carried out to investigate the effect of additives (clay and coal fly ash) and washing-pretreatment on the stabilization of critical heavy metals (Cd, Cu, Zn, Pb, Cr, Ni) during a sintering process of municipal solid waste incinerator (MSWI) fly ash. The proportions of the three constituents were varied to adjust the mixture compositions. The washing time were 8 h, 16 h and 24 h. The material was compacted in cylindrical specimens at 3 kN and treated at 1,100 degrees C for 4 h. When the clay content was increased to 70%, the stabilized ratio was increased from 16.96% to 28.42% for Cd, from 10.58% to 37.02% for Pb, from 46.38% to 55.14% for Cu, from 42.14% to 64.47% for Zn, but the stabilized ratio of Ni and Cr was decreased. When coal fly ash was increased in the MSWI fly ash, the stabilized ratio was decreased from 16.96% to 4.67% for Cd, increased from 46.86% to 81.43% for Cu, but the addition of coal fly ash did not increased the stabilized ratio of Zn, Pb, Ni and Cr. Washing pre-treatment increased the stabilized ratio of Cd, Cu and Pb significantly. The leaching behavior of the heavy metals in the sintered products was studied by the toxicity characteristic leaching procedure (TCLP), the results showed that the leaching concentration of the six heavy metals were very low.

[Accelerated carbonation of high Ca content municipal solid waste incineration fly ash and impact on leaching of heavy metal].

The accelerated carbonation of high Ca content Municipal Solid Waste Incineration (MSWI) fly ash was investigated with an L:S ratio of 0.25:1 to study the effect of accelerated carbonation on the leaching of critical heavy metals (As, Cd, Cu, Zn, Sb, Pb) in the fly ash. The results of XRD analysis showed after carbonation the peaks of Ca(OH)2 and CaClOH disappeared, while the peaks of CaCO3 became intense. After carbonation, the mineral phase of Pb was changed and Cu compound (CuTi2.05S4) was identified. The TG/DTA analysis showed the weight gain of the fly ash before 440 degrees C reached 5.70%. Furthermore, the SEM-EDS analysis confirmed the occurrence of the reaction of Ca(OH)2 (s) + CO2 (g) --> CaCO3 (s). The TCLP test of carbonated fly ash revealed that the leaching concentration of the critical heavy metals, except Cd, decreased within the carbonation time of 2 h. When the carbonation time was longer than 50 h, the leaching concentration of critical heavy metals, except Ph were higher than that of un-carbonated fly ash.

[Components of oil sludge and their influence on pyrolysis behaviors].

Based on property analysis of oil sludge and its main components (mineral oil and minerals), pyrolysis process and releasing behavior of non-condensed gas of oil sludge and its main components were studied by thermogravimetric analysis-fourier transform infrared spectroscopy (TG-FTIR) and tubular resistance furnace, respectively. The results indicated that, (1) Oil sludge was characterized as relatively high heating value (15 422.41 kJ/kg), higher mineral content (61.57%) mainly composed of quartz. Mineral oil component had good thermal conversion property and adhered close with mineral in oil sludge. (2) Pyrolysis process of oil sludge included 5 stages: water volatilization and gas desorption (50-180 degrees C), light oil volatilization (180-370 degrees C), heavy oil pyrolysis (370-500 degrees C), semi-coke charring (500-600 degrees C) and mineral decomposition (higher than 600 degrees C). (3) Minerals influenced oil pyrolysis by surface function and enhancing heating conductivity, meanwhile minor elements in mineral oil could bring mineral decomposition temperature down. (4) Minerals affected the releasing behavior of non-condensed gas from mineral oil pyrolysis and resulted in lower total production and higher H2 production.

[Comparison of fixation effects of heavy metals between cement rotary kiln co-processing and cement solidification/stabilization].

Both cement rotary kiln co-processing hazardous wastes and cement solidification/stabilization could dispose heavy metals by fixation. Different fixation mechanisms lead to different fixation effects. The same amount of heavy metal compounds containing As, Cd, Cr, Cu, Pb, Zn were treated by the two kinds of fixation technologies. GB leaching test, TCLP tests and sequential extraction procedures were employed to compare the fixation effects of two fixation technologies. The leached concentration and chemical species distribution of heavy metals in two grounded mortar samples were analyzed and the fixation effects of two kinds of technologies to different heavy metals were compared. The results show the fixation effect of cement rotary kiln co-processing technology is better than cement solidification/stabilization technology to As, Pb, Zn. Calcinations in cement rotary kiln and then hydration help As, Pb, Zn contained in hazardous wastes transform to more steady chemical species and effectively dispose these heavy metals compounds. Cr3+ is liable to be converted to much more toxic and more mobile Cr6+ state in cement rotary kiln. And so Cr wastes are more fit for treatment by cement solidification/stabilization technology. The work could provide a basis when choosing disposal technologies for different heavy metals and be helpful to improve the application and development of cement rotary kiln co-processing hazardous wastes.

[Dynamic leaching behavior of heavy metals in eco-cement mortar block].

A dynamic leaching test with the renewal of acidic leaching medium was designed to study the leaching behavior of the seven heavy metals (As, Cd, Cr, Cu, Ni, Pb, Zn) in three solidified eco-cement mortar samples with different particle size (fine granule, coarse granule, block) under a long-term leaching condition. It was demonstrated that all the heavy metals were detected in the leachate except Cd. The leaching ratio of Cr was the highest when compared with other metals in the same sample, and the leaching ratio of every metal showed an identical tendency: fine granule> coarse granule > block. The on-going leaching part of the relationship curve of accumulative leaching point (Pt) and t1/2 of each metal presented a fairly good linearity, which indicated that the leaching process was under the control of diffusion mechanism by the Fick Law. To each metal, the effective diffusion coefficient (Deff) showed a tendency of fine granule < coarse granule < block, which was opposite to the tendency of leaching ratio. It could be concluded that the solidified eco-cement mortar with a bigger size would have a lower leaching ratio and a shorter period to finish the leaching test. To all the metals, the Deff was very low, with the magnitude around 10(-10) cm2/s, which meant the leaching process would take a relatively long time.

[Ultrasonic sludge treatment and its application on aerobic digestion].

In order to enhance the degradation efficiency of waste activated sludge (WAS) in conventional aerobic digestion, various ultrasonic assisted treatment methods were investigated including ultrasonic disintegration of influent sludge, ultrasonic improvement of influent sludge activity and ultrasonic disintegration of return sludge. Firstly the effects of ultrasonic sludge treatment were studied to choose appropriate ultrasonic parameters, and then the experiments of aerobic digestion with different ultrasonic treatments were carried out. The results show that 1.0 W/mL, 10 minutes ultrasonic treatment can increase soluble chemical oxygen demand (SCOD) in the supernatant phase of sludge sample by 5.4 times and decrease total suspended solid (TSS) by 16%; 0.05 W/mL, 10 min ultrasonic treatment can increase the specific oxygen uptake rate (SOUR) of sludge sample by 29%. The two kinds of ultrasonic influent sludge pretreatment can't improve aerobic digestion effectively. Ultrasonic return sludge disintegration can enhance the volatile suspended solid (VSS) degradation ratio by 15%. Furthermore, the settlement performance of digested sludge is still good and the pollutant concentrations of supernatant phase increase slightly. So ultrasonic return sludge disintegration is considered as the most appropriate assisted treatment mode for aerobic digestion.

[Vaporization of organic acids from young landfill leachate during evaporation].

To obtain the vaporization rule of organic pollutants in a young landfill leachate, we conducted normal evaporation and gas-carrying evaporation experiments, analyzing TOC and volatile fatty acids (VFAs) of batch condensate. The results showed that TOC in condensates declined when pH was 4, whereas it presented a contrary trend when pH was 7. Variation of VFAs except acetic acid in condensates was similar to that of TOC. The more complicated the chemical construction of VFAs was, the greater the relative rate of vaporization was. The results indicated that the organic matter in condensate from young landfill leachate mainly consisted of VFAs. The quantity change of carried gas didn't distinctly affect the vaporization rule of organic matter in young landfill leachate.

[Experimental research on indirect thermal drying process of sewage sludge].

Technical parameter, condensed steam water quality and flue gases were studied and organic compound hydrolysis mechanism was discussed. During experimental study, observed that the relationship between water content of sewage sludge and residence time have a negative exponential function. The condensed steam water has a high-concentration organic content. Total organic carbon (TOC), volatile fatty acid (VFA) and NH3 -N of the water were very high and the pH value was between 9 and 9.5. VFA and NH3 -N come from two sections: (1) In the 110 - 130 degrees C temperature range, hydrolysis of protein occurred with the formation of VFA and NH3 -N; and (2) In the 140 - 150 degrees C, fats hydrolyzed into VFA. There was no gaseous pollution produced in the whole experimental progress.

[Impact of hydrothermal process on the dewaterability and degrease performance of restaurant garbage].

In order to ameliorate the dewaterability and degrease performance of restaurant garbage, and to improve the treatment effect, a complete trail series with 2 factors on 5 levels was implemented. The 2 factors were temperature and retention time respectively as the main influencing factors of hydrothermal process. By means of analyzing the variation of the resistance, dewatering rate and floatable oil content of the treated restaurant garbage, and constructing the solid grease extracting kinetics, the mechanism of impact of hydrothermal process on the dewaterability and degrease performance of restaurant garbage was studied. It showed that the dewaterability of the product decreases at the beginning, after heating for 40min, it begins to increase. Moreover, it increases more quickly as temperature increases. The optimal dewaterability of the treated garbage appears at 180 degrees C and heating for 100 minutes. As temperature rises and heating time increases, the degrease performance is improved. Furthermore, this trend becomes more remarkably as temperature increases. When the temperature and retention time reach 160 degrees C and 80 minutes respectively, most of the solid grease in the garbage is extracted out to become floatable oil which can be separated and recovered readily. Subsequently, the amount of floatable oil begins to decrease since chemical reactions such as the partial hydrolysis of the oil take place. Additionally, the extraction of solid grease from interior accords with first-order reaction dynamic model.

[Effect of temperature control on vegetable waste and flower straw co-composting].

The effect of temperature control on vegetable waste and flower straw co-composting was investigated in pilot scale. The mixture of shredded vegetable waste and flower straw was composting in 2 m3 static aerobic bed on the controls of three different temperature level (55 degrees C, 60 degrees C, 65 degrees C). Of these trials, temperature, organic matter, moisture content were measured in order to research effect of temperature control on wastes reduction, biodegradation and moisture removal. As the control levels of temperature was 55 degrees C, 60 degrees C, 65 degrees C during composting, the ratios of wastes reduction were 45.8%, 63% and 58.1%, respectively. And the ratiosof wastes biodegradation were 23.4%, 41.4% and 23.8%, respectively. And the ratios of water removal were 59.9%, 79.1% and 78%, respectively. It was the most effective to control temperature of composting on about 60 degrees C among the three control levels of temperature trials, either base of biodegradation or moisture removal. The control temperature of 65 degrees C also have a powerful ability of moisture removal, but its biodegradation is not so efficient as that of 60 degrees C. The control temperature of 55 degrees C have the worst ability to reducing wastes, degrading organic matter and removing water during the co-composting of vegetable and flower wastes.

Fractionation of dissolved organic matter in mature landfill leachate and its recycling by ultrafiltration and evaporation combined processes.

XAD resin procedure was used to isolate dissolved organic matter (DOM) of a mature leachate collected from a municipal solid waste landfill in Beijing, China. The fulvic acids fraction dominated in collected leachate, accounting for 64% of DOM as dissolved organic carbon (DOC), and a high concentration of humic substances (HS) with a value of 441 mg l(-1) was found in the leachate. Molecular size distribution of DOM was also done by using batch ultrafiltration (UF) technique. Two major parts of the molecules of DOM were distributed in the regions of smaller than 1 kDa and 1-3.5 kDa, containing 45% and 43% of DOM as DOC, respectively. The laboratory-scale experiments were conducted to investigate and to develop an overall concept for mature leachate recycling based on UF and evaporation combined processes. Separation factor (SF) was applied to evaluate separation efficiency of UF. The data indicate that SF is strongly correlated with concentration factor. Second retentate from two-stage UF contained relatively high amount of DOM comprising 91% of HS and an insignificant concentration of heavy metals. The SF value for two-stage UF was more than 10. These results demonstrate that two-stage UF could effectively separate and refine HS in mature leachate from inorganic components. For achieving the main requirements as a fertilizer product, second retentate was further concentrated by evaporation, and contents of organic matter and dry-solids were obtained 13 wt.% and 25 wt.%, respectively. This study confirmed the feasibility of recycling HS from mature leachate.

Impact of hydrothermal process on the nutrient ingredients of restaurant garbage.

In order to recover the nutrient resource from restaurant garbage, a complete trial with 2 factors on 5 levels of experiments was carried out. The temperature and heating time are the main factors influencing on hydrothermal process (HP) by which improves the degradability and digestibility of the restaurant garbage favorably to make animal feeds or fertilizer. The results showed the variation of protein, saccharide, and oil in the garbage. It showed that protein dissolved and liquefied during hydrothermal process, which made organic nitrogen in solid phase transfer to liquid phase. After heating at 180 degrees C for 60 min, organic nitrogen in liquid phase began to transform into ammonia. It also showed that hydrothermal process could promote the dextrinization, dissolution of the starch and its hydrolysis to reducing sugar, due to that starch in the restaurant garbage decreases and reducing sugar increases. When the temperature reached 140 degrees C, the reducing sugar started to decrease due to chemical reactions. The cellulose was stable at 100--180cC. The floatable oil increased markedly in the hydrothermal process. The suitable condition for de-oil was observed at 160 degrees C heating for 80 min. Furthermore, the extraction of grease from the solid phase accords with first-order reaction dynamic model.

Isolation and characterization of mesophilic cellulose-degrading bacteria from flower stalks-vegetable waste co-composting system.

Fifteen mesophilic bacteria with high C(x) cellulase activities were isolated and purified from a mixed-culture enriched from a flower stalks-vegetable waste co-composting system. A CMCase test showed that the enzyme activity of these isolates ranged from 7.9 to 28.0 U ml(-1). Although filter paper degrading capability was low in single culture, significant synergetic cellulose degradation were detected in four groups of mixed cultures, their degradation rates were 23.5%, 26.3%, 19.4% and 24.5%, respectively. Study of morphological and physiological characters of five predominant isolates which possess high CMCase and had positive effect on synergetic cellulose degradation in mixed culture system showed that two of them were closely related to Bacillus pasteurii and Bacillus cereus, whereas the rest belong to the genus Halobacillus, Aeromicrobium and Brevibacterium, respectively.

[Migration characteristics of heavy metals during sintering of fly ash from municipal solid waste incinerator].

The sintering process is used to stabilize the heavy metal in fly ash from municipal solid waste incinerator (MSWI). Migration characteristics of 6 targeted heavy metals (Cd, Pb, Cu, Ni, Cr and Zn) in the sintering process of MSWI fly ash were investigated by experiments. Effect of several factors including sintering temperature, residence time, molding pressure and particle diameter on the migration of heavy metals were discussed in details. The results show that cadmium and lead are volatile metals, while nickel, copper, chromium and zinc belong to involatilizable metals. The effects of sintering temperature, residence time, molding pressure and particle diameter on the stabilizing efficiency differ from each other. The study shows that most of heavy metals are stabilized during the sintering process. The stabilizing efficiency of heavy metals was different for different elements.

Effect of inoculating flower stalks and vegetable waste with ligno-cellulolytic microorganisms on the composting process.

A lab-scale composting experiment was carried out using vegetable and flower stalks waste to study the effectiveness of ligno-cellulolytic microorganisms (LCMs) obtained from the previous isolation on composting process, especially on enhancement of biodegradation rate of these organic materials. The addition of LCMs to compost showed promised to be a valuable asset by rendering timely benefits in efficiency, maturity, and quality of the composting. This was evidenced by a significant increase of temperature, O2 consumption and CO2 emission, and population density of LCMs in compost mass compared with that of biotic (addition of culture of horse feces) and abiotic (1% molasses amendment) treatments, as well as control trial. The phytotoxicity assay showed that the substrate became mature after 60 days' composting. The LCMs inoculation enhanced the biodegradation of the composting materials as evidenced by an increasing screening ratio (1.2 cm sieve pore) of 34.5% in the treated trail, compared with that of control, which elucidated that big advantage of adding selected inoculants over other treatment, and screening ratio is a reasonable index to compare the quality of different compost. However, the inoculation seemed to have no significant effect on the moisture content, pH, and the final organic carbon of the composting materials.

[Influence of liquid ceramic additive on binding of heavy metal during the vitrification of fly ash from municipal solid waste incinerator].

Vitrification process can effectively control the leachability of heavy metals in fly ash generated from municipal solid waste incinerator (MWSI). The use of liquid ceramic (LC) additive as a heavy metal chemical stabilization agent was evaluated for MSWI fly ash. The residuals of chromium, lead and zinc in slag increase by different degree with liquid ceramic additive at 1400 degrees C, while those of cadmium and copper decreases. The migrating characteristic of nickel is hardly affected by the additive less than 10%. The volatilization of Cr and Zn occurs after 61 minute with 10% addition of LC, and the binding efficiency of Cr decreases with increasing of melting temperature. The results indicate that the binding efficiency of heavy metals was affected greatly by LC additive and showed significant differences according to type of heavy metal during melting process. The short melting time (no longer than 33 min) is useful to obtain high binding efficiency of heavy metals.

[Influence of additives on decomposition of PCDD/Fs during MSWI fly ash melting process].

The melting process of municipal solid waste incinerator (MSWI) fly ash was investigated in order to study the influence of additives on decomposition characteristics of dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans, PCDD/Fs). The melting treatment of MWSI fly ash was performed at a batch-melting furnace with two types of additives, CaO and liquid ceramic (LC), at different melting temperatures, melting atmospheres and treatment times. The results demonstrate that the effect of CaO on PCDD/Fs' decomposition changed with the type of atmosphere. The decomposition and removal efficiency (DRE) of dioxins increased slightly with 20% CaO in an oxidative atmosphere, while it decreased obviously in an inert atmosphere. There is an important influence by liquid ceramic on the decomposition of PCDD/Fs. The DRE of PCDD/Fs in MSWI fly ash increased from 99.997% to 100% with the addition of LC increasing from zero to 10% at 1400 degrees C. The temperature, in which the PCDD/Fs were completely decomposed, decreased from 1460 degrees C to 1100 degrees C when 10% LC was added into fly ash.