Effects of mixing and covering with mature compost on gaseous emissions during composting.

This study investigated effects of mature compost on gaseous emissions during composting using pig manure amended with corn stalks. Apart from a control treatment, three treatments were conducted with the addition of 5% (wet weight of raw materials) of mature compost: (a) mixing raw materials with mature compost at the beginning of composting; (b) covering raw materials with mature compost throughout the experimental period; and (c) covering raw materials with mature compost at the start of composting, but incorporating it into composting pile on day 6 of composting. Mature compost used for the last treatment was inoculated with 2% (wet weight) of raw materials of strain M5 (a methanotrophic bacterium) solution. During 30-d of composting, three treatments with the addition of mature compost could reduce CH4 emission by 53-64% and N2O emission by 43-71%. However, covering with mature compost throughout the experimental period increased cumulative NH3 emission by 61%, although it could reduce 34% NH3 emission in the first 3d. Inoculating strain M5 in mature compost covered on the top of composting pile within first 6d enhanced CH4 oxidation, but simultaneously increased N2O emission. In addition, mixing with mature compost could improve compost maturity. Given the operational convenience in practice, covering with mature compost and then incorporating it into composting pile is a suitable approach to mitigate gaseous emissions during composting.

[Analysis on the impact of composting with different proportions of corn stalks and pig manure on humic acid fractions and IR spectral feature].

Using pig manure and corn straw as raw materials for high-temperature composting, setting three different treat- ments: C/N 15, C/N 25, and C/N 35. Composting period is 120 days, which contains 30 days for ventilation cycle by forced continuous ventilation. Sampled on 0, 22, 30, 60, 90, 120th days, they were analyzed by elemental analysis and IR spectroscopy to study effect of different lignin content on compost humic acid (HA) composition and molecular structure. The results showed that the change in composting humic acid C focused on the first 30 days, while after composting, the O/C of compost HA increased, H/C decreased, and N content increased. Low C/N (15) and higher C/N ratio (35) had higher degree of oxidation than the C/N 25 in compost HA. FTIR indicated that the infrared spectrum shapes with different lignin content treatment are similar during the composting process, but the peak intensity is obviously different. Research results proved that the composting stage is more conducive to enhanced aromatic in compost HA. After composting, C/N 15 had less polysaccharide and fat ingredients and more aromatic structural components in compost HA, compared with C/N 25 and 35. In addition, compost HA of C/N 15 had higher degree of humification and its structure was more stable.

Influence of bulking agents on CH4, N2O, and NH3 emissions during rapid composting of pig manure from the Chinese Ganqinfen system.

Mismanagement of the composting process can result in emissions of CH4, N2O, and NH3, which have caused severe environmental problems. This study was aimed at determining whether CH4, N2O, and NH3 emissions from composting are affected by bulking agents during rapid composting of pig manure from the Chinese Ganqinfen system. Three bulking agents, corn stalks, spent mushroom compost, and sawdust, were used in composting with pig manure in 60 L reactors with forced aeration for more than a month. Gas emissions were measured continuously, and detailed gas emission patterns were obtained. Concentrations of NH3 and N2O from the composting pig manure mixed with corn stalks or sawdust were higher than those from the spent mushroom compost treatment, especially the sawdust treatment, which had the highest total nitrogen loss among the three runs. Most of the nitrogen was lost in the form of NH3, which accounts for 11.16% to 35.69% of the initial nitrogen. One-way analysis of variance for NH3 emission showed no significant differences between the corn stalk and sawdust treatments, but a significant difference was noted between the spent mushroom compost and sawdust treatments. The introduction of sawdust reduced CH4 emission more than the corn stalks and spent mushroom compost. However, there were no significant differences among the three runs for total carbon loss. All treatments were matured after 30 d.

[Optimization for MSW logistics of new Xicheng and new Dongcheng districts in Beijing based on the maximum capacity of transfer stations].

It is necessary to achieve the optimization for MSW logistics based on the new Xicheng (combining the former Xicheng and the former Xuanwu districts) and the new Dongcheng (combining the former Dongcheng and the former Chongwen districts) districts of Beijing. Based on the analysis of current MSW logistics system, transfer station's processing capacity and the terminal treatment facilities' conditions of the four former districts and other districts, a MSW logistics system was built by GIS methods considering transregional treatment. This article analyzes the MSW material balance of current and new logistics systems. Results show that the optimization scheme could reduce the MSW collection distance of the new Xicheng and the new Dongcheng by 9.3 x 10(5) km x a(-1), reduced by 10% compared with current logistics. Under the new logistics solution, considering transregional treatment, can reduce landfill treatment of untreated MSW about 28.3%. If the construction of three incineration plants finished based on the new logistics, the system's optimal ratio of incineration: biochemical treatment: landfill can reach 3.8 : 4.5 : 1.7 compared with 1 : 4.8 : 4.2, which is the ratio of current MSW logistics. The ratio of the amount of incineration: biochemical treatment: landfill approximately reach 4 : 3 : 3 which is the target for 2015. The research results are benefit in increasing MSW utilization and reduction rate of the new Dongcheng and Xicheng districts and nearby districts.

Effect of bulking agents on maturity and gaseous emissions during kitchen waste composting.

This study investigated the effect of bulking agents on the maturity and gaseous emissions of composting kitchen waste. Three different bulking agents (cornstalks, sawdust, and spent mushroom substrate) were used to compost kitchen waste under aerobic conditions in 60-L reactors for a 28-d period. A control treatment was also studied using kitchen waste without a bulking agent. During the experiment, maturity indexes such as temperature, pH value, C/N ratio, and germination index were determined, and continuous measurements of leachate and gaseous emissions (CH4, N2O, and NH3) were taken. The results showed that all of the composts with bulking agents reached the required maturity standard, and the addition of spent mushroom substrate gave the highest maturity (C/N ratio decreased from 23 to 16 and germination index increased from 53% to 111%). The bulking agents also reduced leachate production and CH4 and N2O emissions, but had little impact on NH3 emissions. Composting with sawdust as a bulking agent was found to emit less total greenhouse gas (33 kg CO2-eqt(-1) dry matter) than the other treatments.

Gaseous emission during the composting of pig feces from Chinese Ganqinfen system.

The Ganqinfen system - a process of manually cleaning animal feces by means of a shovel - is a widely used manure separating method in Chinese pig farms. Ganqinfen pig feces and chopped corn stalks were mixed at the ratio of 7:1, and composted in 1.5 m(3) rotting boxes for 70 d. Evolution of CH(4), N(2)O and NH(3) during composting, and the effects of turning and covering, were studied in this research. Results showed that 20-39% and 0.5-4% of total nitrogen were lost in the form of NH(3) and N(2)O respectively, and 0.1-0.9% of initial organic carbon was emitted as CH(4). Turning enhanced air exchange in the piles, thus decreasing CH(4) emission by 83-93% and shortening the maturing period. When trials were finished, all non-turned piles were separated to three layers by moisture content. This structure caused the N(2)O losses of non-turning treatments to be 6-12.7 times higher than that of turning treatments. Covering materials reduced air exchange at the surface of the pile, thus decreasing the O(2) supply and consequently increasing CH(4) production by 33-45%. Covering also reduced NH(3) emission by 4-34%. For the composting of Ganqinfen pig feces, we suggest that a program of turning twice weekly without covering will result in compost that is sufficiently matured after 6 wk with the lowest resultant greenhouse gas emission.

[Analysis of odor pollutants in kitchen waste composting].

Odor pollution has become a major environmental problem in municipal solid waste composting. The odor samples at different composting phases of kitchen waste were collected and analyzed by olfactometry and gas chromatography-mass spectrometry (GC-MS). The correlation between the odor concentration and the emission of odor compounds was also analyzed. The results showed that there were 43 kinds of volatile organic compounds (VOCs) in the composting process of kitchen waste, including 5 kinds of sulfur odor compounds, 22 kinds of hydrocarbon compounds, 11 kinds of aromatic compounds and 5 kinds of other odor compounds. The correlation analysis indicated that the odor concentration was very significantly correlated with the emission of hydrogen sulfide, methanethiol, 1,3-xylene and o-xylene (P < 0.01), and significantly correlated with the emission of dimethyl disulfide and p-xylene (P < 0.05). Therefore, those 6 kinds of odor compounds should be intensively monitored and controlled during the composting process of kitchen waste.

Chemical precipitation for controlling nitrogen loss during composting.

Aimed at controlling the nitrogen loss during composting, the mixture of magnesium hydroxide (Mg(OH)( 2)) and phosphoric acid (H(3)PO(4)) (molar ratio 1:2) were utilized as additives to avoid increasing total salinity. In trial TA, the additives were put into absorption bottles connecting with a gas outlet of fermentor (ex situ method); in trial TB, the additives were directly added to the composting materials (in situ method). During the 26 day composting period, the temperature, pH, total organic carbon (TOC), total nitrogen (TN), ammonium nitrogen (NH(4)(+)-N), total phosphorus (TP), available phosphorus (AP) and germination index (GI) were measured. The experimental results show that the additives reduced the pH, while NH( 4)(+)-N and TN were obviously improved. NH(4)( +)-N was 11.9 g kg(-1) and 3 g kg(- 1) in amended compost trial (TB) and unamended compost trial (TA), respectively; TN increased from 26.5 g kg(-1) to 40.3 g kg(-1) in TB and increased from 26.5 g kg( -1) to 26.8 g kg(-1) in TA. Analysis of the TOC and carbon mass revealed that absorbents accelerated the degradation of organic matter. The germination index test showed the maturity of TB (102%) was better than TA (82%) in final compost. Furthermore, TP and AP were also obviously improved. X-ray diffraction analysis of precipitation showed that the precipitation in absorption bottle of TA was newberyite (MgHPO( 4) 3H(2)O), however, the crystal in the TB compost was struvite (MgNH(4)PO(4) 6H(2)O: magnesium ammonium phosphate). These results indicated that Mg(OH)(2) and H(3)PO( 4) could reduce the ammonia emission by struvite crystallization reaction. Optimal conditions for struvite precipitation should be determined for different systems.

[Application of struvite crystallization on co-composting of swine manure and cornstalk].

Aimed at controlling the nitrogen loss caused by the ammonia gas emission during composting, the mixtures of magnesium hydroxide [Mg(OH)2] and phosphoric acid (H3PO4) were added into composting materials of swine manure and cornstalk. After 26 d composting, ammonical nitrogen and total nitrogen were improved obviously,which were 10.7 g x kg(-1) and 36.9 g x kg(-1) respectively in amended treatment (B), while they were 7.7 g x kg(-1) and 26.8 g x kg(-1) in un-amended trial. By analysis of the total organic carbon, t suggested that amendments accelerated the degradation of organic matter, germination index test showed the maturity of trial B(96%) was better than trial A(82%) in final compost. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis confirmed the existence of struvite (MgNH4PO4 x 6H2O). These results indicated that Mg (OH)2 and H3PO4 could accelerate the degradation of organic matter, and reduce the ammonia emission by struvite crystallization reaction.

Ambient air monitoring of Beijing MSW logistics facilities in 2006.

In China, "green" integrated waste management methods are being implemented in response to environmental concerns. We measured the air quality at several municipal solid waste (MSW) sites to provide information for the incorporation of logistics facilities within the current integrated waste management system. We monitored ambient air quality at eight MSW collecting stations, five transfer stations, one composting plant, and five disposal sites in Beijing during April 2006. Composite air samples were collected and analyzed for levels of odor, ammonia (NH3), hydrogen sulfide (H2S), total suspended particles (TSPs), carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen dioxide (NO2). The results of our atmospheric monitoring demonstrated that although CO and SO2 were within acceptable emission levels according to ambient standards, levels of H2S, TSP, and NO2 in the ambient air at most MSW logistics facilities far exceeded ambient limits established for China. The primary pollutants in the ambient air at Beijing MSW logistics facilities were H2S, TSPs, NO2, and odor. To improve current environmental conditions at MSW logistics facilities, the Chinese government encourages the separation of biogenic waste from MSW at the source.

[Fuzzy mathematics-based groundwater quality evaluation of six MSW landfills in Beijing].

The qualities of leachate and groundwater of six MSW landfills in wet period, water period and dry period in Beijing in 2006 were analyzed. The results demonstrated that: although BOD5 and suspended solids content in the leachate of Beishenshu landfill were within acceptable levels according to China standards, COD, ammonia, fecal coliform, BOD5 and suspended solids content in other landfills were greatly high above the permissible range of GB 16889-1997 standards. Ammonia and fecal coliform were mostly serious among assaying index. Using fuzzy mathematics, comprehensive evaluation was that: the underground water qualities of six MSW landfills are all substandard and 95% of groundwater quality was bad. The primary pollutants in groundwater of six MSW landfills were total hardness, followed by fecal coliform.

[Interaction between carbaryl and calf thymus DNA enhanced via Cu2+].

The interaction between carbaryl and calf thymus DNA with Cu2+ was studied using fluorescence spectroscopy (FS) and UV spectrum. The quenching process was proved to be single static quenching and the quenching constant decreases with temperature increasing. The experimental results showed that the carbaryl can be intercalated into the twin-screw structure of calf thymus DNA, forming ctDNA-carbaryl adducts. The UV spectrum showed that ctDNA can also result in the increasing color and red shift. In the presence of Cu2+, it was discovered that the apparent association constant (Kalpha) increases and the binding sites number (n) of carbaryl molecules on ctDNA obviously increases. The interaction of the carbaryl and ctDNA was driven mainly by electrostatic force which was enhanced by Cu2+, thus the contribution of deltaH to deltaG increased in the presence of Cu2+ So the interaction between carbaryl and calf thymus DNA was enhanced via Cu+.

[Effects of surfactants on adsorption of methyl parathion by neutral alumina].

The sorption of methyl parathion by neutral alumina which was modified by ionic surfactants such as SDS, SDBS and CTMAB was studied. It showed that the adsorbability of alumina to methyl parathion were related to the type and concentration of surfactant and pH of the system. The adsorbabilities of alumina on three kinds of surfactants were different. When pH = 7, the adsorbance of SDS was the largest, but the adsorbance of CTMAB was the smallest. When pH = 4, the adsorbance of SDS or SDBS was increased, while the adsorbance of CTMAB was decreased. The adsorbability of alumina was strengthened, not weakened, by the cooperation of pollutant and anionic surfactant, while the sorption of methyl parathion by alumina with cationic surfactant was weakened. These features had the practical value when neutral alumina is used to remove more than one contaminants from wastewater.

Influence of furfural concentration on growth and ethanol yield of Saccharomyces kluyveri.

Furfural is an important inhibitor in ethanol fermentation process using lignocellulosic hydrolysates as raw materials. In order to find out the furfural concentration range in which furfural inhibits the fermentation process, we used one strain Saccharomyces kluyveri selected from soil and cultured in several different furfural content media under low glucose concentration condition. Experiment results showed that microorganism growth was stimulated and dry cell weight decreased when furfural concentration in the medium was 0.25 mg/ml. Furfural had negative effect on cell growth when its concentration was above 1.00 mg/ml. At the same time, the strain growed better and had a higher glucose consumption rate in 5% original glucose concentration condition than in 3% original glucose concentration condition. The results showed that appropriate exaltation of original glucose concentration in stalk hydrolysates will increase the strain resistance to furfural.

[Construction and function of a high-efficient complex microbial system to degrade cellulose and lindane in compost].

A complex microbial system capable of degrading cellulose and lindane with high efficiency was isolated from four compost heaps. It was selected and domesticated through two methods and by combination of different microbial communities. The results show that the complex microbial system can decompose filter paper, absorbent cotton, rice straw powder and sawdust effectively, especially has high degrading activity for the materials with higher native cellulose such as filter paper and absorbent cotton. As for both of them, the CMC saccharification activity is more than 40U and the degradation efficiency is more than 95% on the 5th day of inoculation. The complex microbial system can also keep a higher degrading capability in a wider range of pH. Filter paper and lindane can be degraded effectively by the complex microbial system during pH 7.0 - 9.0, and the degradation rates are more than 90 % and 45% respectively. Under pH 6.0 - 9.0, there is a good consistency between the degradation of Lindane and the decomposition of filter paper.

[The mechanism of carbofuran interacts with calf thymus DNA].

Carbofuran is an insecticide used on a variety of corps. Acute and chronic occupational exposure of humans to carbofuran has been observed to cause cholinesterase inhibition, but little is known about the interaction of carbofuran with DNA. Using the technique of UV spectrum and fluorescence quenching respectively, the interaction between carbofuran and ct DNA was studied. The UV spectrum showed that ct DNA can lead to the hypochromic effect and red shift of the UV spectrum of carbofuran. The quenching process was proved to be the single static quenching and quenching constant decreases with temperature increasing. The basis of this specificity is intercalation of insecticide between base pairs to produce ct DNA-carbofuran adducts. Furthermore, ethanol can produce Franck-condon effect on the ct DNA-carbofuran adducts. At different sodium chloride concentrations, quenching constant had no significant change, which appeared that there was little electrostatic interaction between ct DNA and carbofuran and it was intercalation.

Clomazone dissipation, adsorption and translocation in four paddy topsoils.

Laboratory experiments about the dissipation, adsorption and translocation in four paddy topsoils were conducted in this paper. From the results it can be concluded as follows: the dissipation rate of clomazone differed greatly in different paddy soil derived from different parent materials. The half-lives for clomazone degradation in paddy soils ranged from 5.7 to 22.0 d. The order of clomazone dissipation rate was reddish yellow paddy soil > alluvial sandy paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Clomazone sorption quantity was significantly correlated with organic carbon (R2 = 0.62) and clay content(R2 = 0.67) in the tested paddy soils. Positive correlation was found between apparent Kd value and cation exchange content(CEC). The consequences for the adsorption of different soils were purple sandy paddy soil > yellow clayey paddy soil > reddish yellow paddy soil > alluvial sandy paddy soil. Under the simulated rainfall of 200 mm through four different unsaturated soil lysimeters over 24 h, clomazone was readily to be leached into lower surface soil and there was about 2.6%--4.2% of applied clomazone leached out of 20 cm cultivated soil layer. Translocation experiments showed that the order of clomazone leaching ability was: alluvial sandy paddy soil > reddish yellow paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Simple regression results manifested that factors like CEC, organic carbon, clay, and adsorption rate constant had been negatively correlated with the percentage of clomazone loss from soil lysimeters.

Assessment on the pollution of nitrogen and phosphorus of Beijing surface water based on GIS system and multivariate statistical approaches.

This paper presented the characteristics of nitrogen and phosphorus pollution in Beijing surface water during the survey. A significant difference was found out in concentration distribution of various parameters of nitrogen and phosphorus. Most water bodies in five water systems were polluted by total nitrogen with the content even up to 120 mg/L which was higher than exceeded the fifth class standard of national surface water quality standard GB3838-2002 except for several segments of Chaobaihe and Yongdinghe. Ammonia and phosphorus showed a similar tendency of distribution with higher content in Daqinghe, Beiyunhe and Jiyunhe water systems, but with relatively low concentrations in Chaobaihe and Yongdinghe water systems. Meanwhile, nitrate was found at comparatively low content (mostly less than 10 mg/L) and could fit for corresponding water quality requirements. Totally, the water quality of Daqinghe, Jiyunhe and Beiyunhe river systems as well as the lower reaches of Yongdinghe and Chaobaihe was contaminated seriously with high content of total nitrogen and phosphorus. Through multivariate statistical approaches, it can be concluded that total nitrogen, ammonia and total phosphorus was highly correlated to chemical oxygen demand, biochemical oxygen demand, dissolved oxygen and electrical conductivity, which explained the same pollution source from anthropogenic activities.