生活垃圾焚烧废气中二噁英监测采样研究

对当前国内生活垃圾焚烧废气中二噁英监测相关标准和技术规范的解读和实践操作后,认识到生活垃圾焚烧废气中二噁英监测采样的现状及不足.针对不同类型烟道,不同采样时间和不同采样时间间隔分别进行了研究.实验结果表明,同一稳定气流的排放源中,水平烟道和垂直烟道测试二噁英毒性当量排放浓度水平相当;满足监测采样量要求下,不同采样时间和采样时间间隔对二噁英监测结果并无显著差异,对此给出几点相应采样建议.     

碳源对厌氧氨氧化脱氮性能影响的试验研究

分别研究了无机碳源和有机碳源对厌氧氨氧化反应脱氮性能的影响。接种稳定运行的复合式UASB厌氧氨氧化反应器污泥至ASBR反应器进行批式试验,考察不同碳酸氢钠浓度及COD浓度条件下的氮素转化情况,研究碳源对厌氧氨氧化脱氮效果的影响。厌氧氨氧化反应适宜的进水碳酸氢钠浓度为1.5～2.0 mg/L,超过30 mg/L时有机碳源的存在对厌氧氨氧化反应产生抑制作用,COD浓度超过60 mg/L时反应器表现出反硝化特性。无机碳源对厌氧氨氧化反应的影响表现在提供充足碳源和调节反应器pH的综合作用,较高浓度的COD对厌氧氨氧化反应具有抑制作用。     

Investigation of acetylated kapok fibers on the sorption of oil in water

Kapok fibers have been acetylated for oil spill cleanup in the aqueous environment. The structures of raw and acetylated kapok fiber were characterized using Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Without severe damage to the lumen structures, the kapok fibers were successfully acetylated and the resulting fibers exhibited a better oil sorption capacity than raw fibers for diesel and soybean oil. Compared with high viscosity soybean oil, low viscosity diesel shows a better affinity to the surface of acetylated fibers. Sorption kinetics is fitted well by the pseudo second-order model, and the equilibrium data can be described by the Freundlich isotherm model. The results implied that acetylated kapok fiber can be used as the substitute for non-biodegradable oil sorption materials.     

Investigation of low-molecular weight organic acids and their spatiotemporal variation characteristics in Hongfeng Lake, China

The identities and concentrations of low-molecular-weight organic acids (LMWOAs) were determined by ion chromatography throughout a 20-m water column in Hongfeng Lake, China. The spatiotemporal variations of LMWOAs and their contributions to dissolved organic matter (DOM) in a research period of 24 hr were also investigated. The results demonstrated that five LMWOAs (lactic, acetic, pyruvic, sorbic, oxalic acid) were detected, and their total concentration and proportion in DOC were 6.55 μmol/L and 7.47%. Their average levels were 2.50, 0.65, 2.35, 0.96 and 0.09 μmol/L, respectively. LMWOAs were higher during daytime (10:00-18:00 on Jun 13, 2008) than nighttime (21:00-6:00 the next morning), in particular 4.99 μmol/L high in the epilimnion ( 1 m water depth), reflecting the fact that direct import from terrigenous sources and photochemical production from humic materials were dominant during LMWOAs’ origin and accumulation. The same factors caused LMWOAs to be 0.63 μmol/L in the epilimnion higher than in the hypolimnion. The rapid decrease of total organic acid (TOA) up until 18:00 mainly resulted from bio-uptake and mineralization in the hypolimnion (>1 m water depth). Pyruvic acid increased with time in the epilimnion and decreased in the hypolimnion, largely related to the two contrary processes of continuous degradation and synthesis of macromolecular organic matter during life materials’ cycle mediated by organisms. Simultaneously, plankton behavior and thermal stratification played a pivotal role in LMWOAs’ behavior in the water column, causing decreasing and increasing profiles. The distribution of LMWOAs represents an interesting resource for biogeochemical research of DOM in aquatic ecosystems.     

Factors influencing the contents of metals and As in soils around the watershed of Guanting Reservoir, China

Topsoil samples from 61 sites around the Guanting Reservoir,China,were measured for Cu,Zn,Cr,Ni,Cd,Pb and As concentrations.The mean concentrations of Cu,Zn,Cr,Ni,Cd,Pb and As were 16.8,59.4,37.8,18.3,0.32,20.1 and 8.67 mg/kg dry weight,respectively.Factors that influence the dynamics of these metals in soils around the watersheds of Beijing reservoirs were examined.The influence of atmospheric deposition,land use,soil texture,soil type and soil chemical parameters on metal contents in soils was investigated.Atmospheric deposition,land use and soil texture were the important factors affecting heavy metal residues.Soil type and soil chemical parameters were also involved in heavy metal retention in soils.The data provided in this study are considered crucial for reservoir remediation,especially since the Guanting Reservoir will serve as one of the main drinking water sources for Beijing in the foreseeable future.     

Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China

The concentrations and geographical distribution of hexabromocyclododecane (HBCD) were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection (LOD) to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of HBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that γ-HBCD dominated in most of the sediment samples, followed by α- and β-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm 2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.     

Removal and transformation of organic matters in domestic wastewater during lab-scale chemically enhanced primary treatment and a trickling filter treatment

To find a simple and economical way for treating the domestic wastewater in small counties and towns, a process combining chemically enhanced primary treatment and a trickling filter (CEPT-TF, representing the physical and biological effects) was constructed and operated in laboratory conditions. The characteristic behaviors of dissolved organic matter in raw wastewater and effluents were examined during steady-state operation. Experimental results showed that the process of CEPT and TF in series was beneficial for the removal of hydrophobic and hydrophilic organics. Specially, the hydrophobic and aromatic materials could be preferentially removed in the CEPT unit, and the hydrophilic fraction in the TF. Structural changes of the organic fractions during the operation of the different units were also characterized via spectrum analysis.     

Cost-performance analysis of nutrient removal in a full-scale oxidation ditch process based on kinetic modeling

A full-scale oxidation ditch process for treating sewage was simulated with the ASM2d model and optimized for minimal cost with acceptable performance in terms of ammonium and phosphorus removal. A unified index was introduced by integrating operational costs (aeration energy and sludge production) with effluent violations for performance evaluation. Scenario analysis showed that,in comparison with the baseline (all of the 9 aerators activated), the strategy of activating 5 aerators could save aeration energy significantly with an ammonium violation below 10%. Sludge discharge scenario analysis showed that a sludge discharge flow of 250–300 m3/day (solid retention time (SRT), 13–15 days) was appropriate for the enhancement of phosphorus removal without excessive sludge production. The proposed optimal control strategy was: activating 5 rotating disks operated with a mode of "111100100" ( "1"represents activation and "0" represents inactivation) for aeration and sludge discharge flow of 200 m3/day (SRT, 19 days). Compared with the baseline, this strategy could achieve ammonium violation below 10% and TP violation below 30% with substantial reduction of aeration energy cost (46%) and minimal increment of sludge production (< 2%). This study provides a useful approach for the optimization of process operation and control.     

短程硝化颗粒污泥的快速培养与硝化特性研究

以城市污水处理厂剩余污泥为种泥,以2 min沉淀时间为选择压,在序批式反应器(SBR)中快速培养出好氧颗粒污泥。经过60个周期(20 d),反应器内出现砂粒状颗粒,并持续稳定运行120 d。成熟的颗粒污泥平均粒径856.56μm,具有良好的硝化性能。SBR反应器以固定曝气时间方式运行,亚硝酸盐积累率达80%以上,实现了稳定短程硝化。试验结果表明:絮体污泥(即接种污泥)与颗粒污泥的硝化过程相似但略有差异。二者差别在于,氨氮氧化结束后,继续曝气120 min,絮体污泥将亚硝酸盐完全转化为硝酸盐,而颗粒污泥仅将部分亚硝酸盐转化且过程比较缓慢。     

餐厨垃圾与污水污泥共消化产酸试验研究

研究了餐厨垃圾与污水污泥在不同混合比例、不同污泥停留时间条件下的共消化产酸效果。试验结果表明:当餐厨垃圾与污水污泥TS比为1∶3时,SRT=1 d的反应器酸化效率最高,且乙酸含量占优,产酸效果较佳;当TS之比为1∶1时,各反应器产酸量普遍高于1∶3时,其中SRT=5 d产酸反应器,最高酸化效率达5.94,产酸量最大,且乙酸含量占优,运行效果最佳。