Prediction of the amount of urban waste solids by applying a gray theoretical model

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An improved product-process for cleaner chrome tanning in leather processing

Severe restrictions imposed by the pollution control authorities on the disposal of chromium, total dissolved solids and chlorides in tannery effluents have forced the tanners to look for low-waste, high exhaust chrome tanning salts. An improved chrome syntan with more than 90% uptake of chrome has been developed. The new product serves both as tanning and retanning agent and can be applied directly to delimed pelts thus eliminating the conventional pickling stage in the leather processing. This modified process helps to reduce the chemical oxygen demand (COD), total dissolved solids (TDS) and chlorides in the spent tan liquor by 51, 81 and 99%, respectively. The product offers full, soft leathers having shrinkage temperature comparable to conventional chrome tanned skins. Since the developed product is highly reactive, it saves time and reduces the water requirement when compared to the conventional chrome tanning method. Thus the novel product/process developed not only has advantages in reducing pollution loads but also seems to be techno-economically viable.     

气浮工艺对矿井废水中悬浮物去除的实验研究

我国每年排放大量的矿井废水，其中含有大量的悬乳物，不加以处理直接排放会对环境造成严重污染。本实验采用汽浮工艺对矿井废水中悬浮物的去除进行实验研究，得出气浮工艺的最佳工艺参数，悬浮物去除率达98%以上，为生产性应用提供理论依据。     

太湖真光层深度谱的分布特征及其介质影响探究

基于2010年5月份全湖28个站点分层测量的水体下行辐照度以及各光学介质(有机悬浮物LOI、无机悬浮物ISS、叶绿素a Chl-a)浓度的实测数据,本文运用岭回归分析法,分析了不同湖区5月份真光层深度谱的分布特征及其影响因素.结果表明整个有效光合辐射范围内,3种因素对真光层深度的贡献均为负,ISS浓度是真光层深度的主要贡献因子,贡献率达0.48~0.62;其次为LOI浓度,贡献率为0.34~0.45;Chl-a浓度的贡献最小,贡献率为0.05~0.09.675 nm处,ISS的贡献具有谷值,Chl-a与LOI的贡献却为峰值;520~650 nm处Chl-a贡献值保持低值.此外,按各采样点的真光层深度谱分布的线型向量空间余弦相似度(cosine)进行分步聚类(Ascending Hierarchical),将全湖分为二类,梅梁湾、竺山湾、贡湖湾以及胥口湾以北区域为第一类,其余区域为第二类.结合全湖所有采样点的各介质浓度数据,发现第一类采样点LOI与Chl-a的相对浓度大于第二类,此两类介质浓度凸显了650 nm、675 nm处真光层深度谱分布曲线的波谷特征.     

操作条件对膜生物反应器运行经济性的影响

以运行费用作为膜生物反应器(MBR)运行经济性的考核指标,建立了MBR运行费用的计算模型,重点考察了膜通量、曝气强度、抽停时间、混合液悬浮固体质量浓度等操作条件对MBR运行经济性的影响.结果表明,膜通量在临界值5 L/(m2·h)时运行费用处于最低值;曝气强度过高或过低都会使系统运行费用增加,而经济曝气强度(气水比)为30:1;当抽吸时间≤12 min、停抽时间≥3 min时,运行费用变化缓慢,但抽吸时间或停抽时间超过临界值后,运行费用迅速上升;混合液悬浮固体质量浓度高于5.0 g/L时,运行费用随混合液悬浮固体质量浓度增加迅速递增.工程运行表明,运行费用模型预测值与实际值具有较好的一致性.     

Preventive control of odor emissions through manipulation of operational parameters during the active phase of composting

Better understanding of the effects of key operational parameters or environmental factors on odor emission is of critical importance for minimizing the generation of composting odors. A series of laboratory experiments was conducted to examine the effects of various operating conditions on odor emissions. The results revealed that airflow rates that were too high or too low could result in higher total odor emissions. An optimal flowrate for odor control would be approximately 0.6 L/min.kg dry matter with intermittent aeration and a duty cycle of 33%. Temperature setpoint at 60°C appeared to be a turning point for odor emission. Below this point, odor emissions increased with increasing temperature setpoint; conversely, odor emissions decreased with increasing temperature setpoint above this point. With regard to the composting material properties, odor emissions were greatly affected by the initial moisture content of feedstock. Both peak odor concentration and emission rate generally increased with higher initial moisture content. Odor emission was significant only at moisture levels higher than 65%. An initial moisture level below 45% is not recommended due to concern with the resulting lower degree of biodegradation. Biodegradable volatile solids content (BVS) of feedstock had pronounced effect on odor emissions. Peak odor concentration and emission rate increased dramatically as BVS increased from 45% to 65%, thus, total odor emission increased exponentially with BVS.     

湖泊沉积物短时间反复扰动下悬浮物上生物有效磷的动态变化

以太湖梅梁湾、月亮湾的沉积物和上覆水为材料,研究了较短时间尺度和沉积物反复扰动条件下,悬浮物中不同形态生物有效磷数量分布的变化特征.结果表明,随着扰动次数的增加,上覆水中藻类可利用磷(AAP)占溶解态总磷(DTP)的百分比均有所降低.试验期间,悬浮物中弱吸附态磷(NH4Cl-P)、可被生物利用颗粒态磷(BAPP)占总磷(Tot-P)的百分比平均值分别增加了3.5%、37.3%(梅梁湾)和2.0%、50.7%(月亮湾).梅梁湾悬浮物上AAP含量及其占Tot-P的百分比随扰动次数增加而增加,月亮湾则恰好相反.扰动期间,悬浮物上BAPP含量始终大于NH4Cl-P和AAP之和,表明BAPP的80%是由NH4Cl-P和AAP组成的.这也暗示了,仅仅以悬浮物中NH4Cl-P、AAP来估算BAPP存在一定的不合理性.     

Modeled Sources,Transport, and Accumulation of Dissolved Solids in Water Resources of the Southwestern United States1

Anning, David W., 2011. Modeled Sources, Transport, and Accumulation of Dissolved Solids in Water Resources of the Southwestern United States. Journal of the American Water Resources Association (JAWRA) 47(5):1087‐1109. DOI: 10.1111/j.1752‐1688.2011.00579.x Abstract: Information on important source areas for dissolved solids in streams of the southwestern United States, the relative share of deliveries of dissolved solids to streams from natural and human sources, and the potential for salt accumulation in soil or groundwater was developed using a SPAtially Referenced Regressions On Watershed attributes model. Predicted area‐normalized reach‐catchment delivery rates of dissolved solids to streams ranged from <10 (kg/year)/km² for catchments with little or no natural or human‐related solute sources in them to 563,000 (kg/year)/km² for catchments that were almost entirely cultivated land. For the region as a whole, geologic units contributed 44% of the dissolved‐solids deliveries to streams and the remaining 56% of the deliveries came from the release of solutes through irrigation of cultivated and pasture lands, which comprise only 2.5% of the land area. Dissolved‐solids accumulation is manifested as precipitated salts in the soil or underlying sediments, and (or) dissolved salts in soil‐pore or sediment‐pore water, or groundwater, and therefore represents a potential for aquifer contamination. Accumulation rates were <10,000 (kg/year)/km² for many hydrologic accounting units (large river basins), but were more than 40,000 (kg/year)/km² for the Middle Gila, Lower Gila‐Agua Fria, Lower Gila, Lower Bear, Great Salt Lake accounting units, and 247,000 (kg/year)/km² for the Salton Sea accounting unit.     

Long‐Term Trends of Specific Conductance in Waters Discharged by Coal‐Mine Valley Fills in Central Appalachia,USA

Anthropogenic salinization of freshwaters is a global concern. Coal surface mining causes release of dissolved sulfate, bicarbonate, calcium, magnesium, and other ions to surface waters in central Appalachia, USA, through practices that include mine rock disposal in valley fills (VFs). This region's surface waters naturally have low salinity, with specific conductance (SC, a salinity indicator) generally <200 μS/cm, and aquatic impacts have been found when SC exceeds the 300 to 500 μS/cm range. We analyzed SC in waters emerging from 137 VFs over periods of 1 to 23 years. Mean SCs for these VFs ranged from 227 to 2,866 μS/cm, generally rose during and immediately following construction, but often declined during latter portions of longer monitoring records. Seventy‐four of 103 VFs with postconstruction data had SC trends that fit negative quadratic forms. Of the 16 revegetated VFs with at least five years of SC data past the quadratic maximum, the mean quadratic maximum was 1,464 (±696) μS/cm and the model projected time required to approach natural conditions (by declining to <500 μS/cm) was 19.6 (±6.6) years after VF construction initiation, indicating long‐lasting but not permanent aquatic impacts due to elevated (>500 μS/cm) SC.     

矿化度对淡水浮游植物生长及群落结构的影响

以博斯腾湖原水为培养液,通过添加SO₄2-和Cl-调节培养液的矿化度分别为0.5、1.5、3.5、10.0g/L,考察不同矿化度对浮游植物生长及群落结构的影响. 结果表明:在对数生长期内,浮游植物生物量、比增长率及ρ(Chla)均随矿化度的增加而升高;生长后期高矿化度(10.0g/L)对浮游植物有抑制作用. 在各矿化度下的浮游植物优势门类均为硅藻门,其生物量占藻类总生物量的95%以上. 随着矿化度升高,蓝藻门有较好的适应性,能够生长,但绿藻门受到明显抑制. 试验显示,优势属为脆杆藻(Fragilaria)、针杆藻(Synedra)、舟形藻(Navicula)和羽纹藻(Pinnularia). 矿化度为0.5g/L时很少出现舟形藻,但随着矿化度的升高,舟形藻逐渐成为优势种,其生物量占18.51%~26.18%;羽纹藻生物量在矿化度为0.5和1.5g/L时所占比例分别达3.40%和4.94%,在高矿化度(3.5~10.0g/L)下则极少出现,不再具有优势. 研究表明,舟形藻和羽纹藻可作为博斯腾湖咸化过程的参考藻种.