Extraction of raw sewage sludge containing iron phosphate for phosphorus recovery

The objective of the present study was to establish an alkali extraction technology for FePO₄-containing sewage sludge obtained from a wastewater treatment system that includes phosphorous removal by iron electrolysis. By clarifying the extraction properties of phosphorous, organic matter, and inorganic matter, conditions for alkali extraction were optimized. As a result, it was suggested that unheated phosphorous extraction would be superior for FePO₄-containing sewage sludge. And, extraction methods and sewage sludge properties were also compared, and the noteworthy result that extraction of metals can be suppressed to extremely low amounts with alkali extraction as compared with acid extraction was obtained. A new insight was also gained that, as compared with the use of incinerated ash reported in previous studies, alkali extraction was more efficient when raw sewage sludge was used.     

Biofilm formation and microbial community analysis of the simulated river bioreactor for contaminated source water remediation

Background, aim, and scope

The start-up pattern of biofilm remediation system affects the biofilm characteristics and operating performances. The objective of this study was to evaluate the performances of the contaminated source water remediation systems with different start-up patterns in view of the pollutants removal performances and microbial community succession.

Methods

The operating performances of four lab-scale simulated river biofilm reactors were examined which employed different start-up methods (natural enrichment and artificial enhancement viadischarging sediment with influent velocity gradient increase) and different bio-fillers (Elastic filler and AquaMats? ecobase). At the same time, the microbial communities of the bioreactors in different phases were analyzed by polymerase chain reaction, denaturing gradient gel electrophoresis, and sequencing.

Results and discussion

The pollutants removal performances became stable in the four reactors after 2 months?? operation, with ammonia nitrogen and permanganate index (COD_Mn) removal efficiencies of 84.41?C94.21% and 69.66?C76.60%, respectively. The biomass of mature biofilm was higher in the bioreactors by artificial enhancement than that by natural enrichment. Microbial community analysis indicated that elastic filler could enrich mature biofilm faster than AquaMats?. The heterotrophic bacteria diversity of biofilm decreased by artificial enhancement, which favored the ammonia-oxidizing bacteria (AOB) developing on the bio-fillers. Furthermore, Nitrosomonas- and Nitrosospira-like AOB coexisted in the biofilm, and Pseudomonas sp., Sphaerotilus sp., Janthinobacterium sp., Corynebacterium aurimucosum were dominant in the oligotrophic niche.

Conclusion

Artificial enhancement via the combination of sediment discharging and influent velocity gradient increasing could enhance the biofilm formation and autotrophic AOB enrichment in oligotrophic niche.     

Can body-size patterns of ciliated zooplankton be used for assessing marine water quality? A case study on bioassessment in Jiaozhou Bay, northern Yellow Sea

Introduction

In order to reveal the potential relationships between body-size patterns of microzooplankton and environmental status, the spatial patterns in body-size spectra of ciliated zooplanktons were studied based on an annual dataset in a bay of the Yellow Sea, northern China.

Materials and methods

A total of 120 samples were collected at a depth of 1?m from each of five sampling sites with a spatial gradient of environmental stress from June 2007 to May 2008. A range of physico-chemical variables were measured synchronously for comparison with biotic parameters.

Results

The spatial body-size patterns of ciliated zooplankton represented significant differences among the five sites, and were significantly correlated with the changes of physico-chemical parameters, especially salinity, dissolved oxygen and nutrients. Two paired indices, the average body-size distinctness (AvBSD) and the variation in body-size distinctness (VarBSD), were proposed based on the trait resemblances among ciliate species in body-size pattern. The paired measures showed a clear decreasing trend of departure from the expected body-size spectra in response to water quality status.

Conclusion

These results suggest that the body-size pattern of ciliated zooplankton might be used as a potential indicator of marine water quality.     

Characteristics of precipitation chemistry at Lushan Mountain, East China: 1992–2009

Introduction

Trends in precipitation pH and conductivity during 1992?C2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35?C5.01 and showed a statistically very significant (P?P?Results and discussions Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO ₄ ^2? and NO ₃ ^? were the main anions, and NH ₄ ⁺ and Ca²⁺ the main cations. The anion to cation ratio was 0.8?C1.0, and that of [SO ₄ ^2? ] to [NO ₃ ^? ] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH ₄ ⁺ ] to [Ca²⁺] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl^?] to [Na⁺] was about 0.67, somewhat lower than that of natural precipitation.

Conclusions

Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry.     

Environmental lead pollution threatens the children living in the Pearl River Delta region, China

Introduction and purpose

The objective of this study is to determine children??s blood lead levels and identify sources of lead exposure. Childhood lead exposure constitutes a major pediatric health problem today in China. A blood lead screening survey program for children in the age group of 2?C12?years residing in Pearl River Delta region, south of China, was carried out from Dec 2007 to Jan 2008.

Methods

Blood lead levels and lead isotope ratios of a total of 761 participants were assessed by inductively coupled plasma mass spectroscopy. Measurements of urban environmental samples for source identification of children lead exposure were also performed.

Results and conclusions

The geometric mean value of the children??s blood lead levels was 57.05???g/L, and 9.6% of them were higher than 100???g/L. The blood lead levels were still much higher than those in developed countries. Based on the data of environmental lead source inventories, lead isotopic tracing revealed that there is about 6.7% past used gasoline Pb embedded in Shenzhen residential dust and about 15.6% in Guangzhou dust, respectively.     

Urban transformation of a metropolis and its environmental impacts

Purpose

The aim of this paper is to understand the sustainability of urban spatial transformation in the process of rapid urbanization, and calls for future research on the demographic and economic dimensions of climate change. Shanghai towards its transformation to a metropolis has experienced vast socioeconomic and ecological change and calls for future research on the impacts of demographic and economic dimensions on climate change. We look at the major questions (1) to explore economic and demographic growth, land use and land-cover changes in the context of rapid economic and city growth, and (2) to analyze how the demography and economic growth have been associated with the local air temperature and vegetation.

Method

We examine urban growth, land use and land-cover changes in the context of rapid economic development and urbanization. We assess the impact of urban expansion on local air temperature and vegetation. The analysis is based on time series data of land use, normalized difference vegetation index (NDVI), and meteorological, demographic and economic data.

Results and discussion

The results indicate that urban growth has been driven by mass immigration; as a consequence of economic growth and urban expansion, a large amount of farmland has been converted to paved road and residential buildings. Furthermore, the difference between air temperature in urban and exurban areas has increased rapidly. The decrease of high mean annual NDVI has mainly occurred around the dense urban areas.     

不同粒径零价铁（ZVI）对污水污泥H_2S和CH_4释放速率的影响

考察了不同粒径零价铁（ZVI）,包括200目普通铁粉（200m-ZVI）、800目超细铁粉（800m-ZVI）和纳米铁粉（nZVI,粒径=20 nm）,对污水污泥的硫化氢和甲烷释放速率的影响。研究发现：（1）在22 d内,添加0.1%的200m-ZVI使污泥的硫化氢释放速率提高48.0%,而添加0.1%的800-ZVI和nZVI,则使污泥的硫化氢释放速率分别降低33.1%和77.1%;（2）不同粒径ZVI均可以提高污泥沼气中的甲烷浓度,且依次为nZVI〉800m-ZVI〉200m-ZVI;（3）在23 d内,添加0.1%的200m-ZVI和nZVI使污泥的甲烷累计产生量分别提高了15.5%和40.6%,而添加0.1%800m-ZVI则使甲烷产生量降低了12.5%。nZVI可以有效控制污泥的硫化氢释放,并显著提升污泥在厌氧发酵过程的产甲烷速率。     

Determination of partition and diffusion coefficients of formaldehyde in selected building materials and impact of relative humidity

The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50%, and 70% RH). The "green" materials contained recycled materials and were friendly to environment. A dynamic dual-chamber test method was used. Results showed that a higher relative humidity led to a larger effective diffusion coefficient for two kinds of wallboards and carpet. The carpet was also found to be very permeable resulting in an effective diffusion coefficient at the same order of magnitude with the formaldehyde diffusion coefficient in air. The partition coefficient (K(ma)) of formaldehyde in conventional wallboard was 1.52 times larger at 50% RH than at 20% RH, whereas it decreased slightly from 50% to 70% RH, presumably due to the combined effects of water solubility of formaldehyde and micro-pore blocking by condensed moisture at the high RH level. The partition coefficient of formaldehyde increased slightly with the increase of relative humidity in "green" wallboard and "green" carpet. At the same relative humidity level, the "green" wallboard had larger partition coefficient and effective diffusion coefficient than the conventional wallboard, presumably due to the micro-pore structure differences between the two materials. The data generated could be used to assess the sorption effects of formaldehyde on building materials and to evaluate its impact on the formaldehyde concentration in buildings.     

人工湿地构筑根孔作用下土壤物质分布状况

嘉兴市石臼漾湿地应用人工构筑根孔技术,以玉米秸秆和油菜秸秆按比例混合埋植于土壤亚表层,作为湿地的基质/填料。在湿地运行一年半后,按照正交设计表,以埋植秸秆的种类(S)、填埋的土壤层次(L)、距离秸秆外环的远近(D)和秸秆周围土壤的表观颜色(C)作为实验因素,对秸秆周围养分物质浓度、土壤酶活性以及铁含量进行采样分析。实验结果显示:玉米秸秆和油菜秸秆腐烂较充分,分别形成较发达的粗根孔和细根孔;根孔周围土壤呈中度还原状态;粗根孔具有较强的优先流效应,其周围土壤具有较高的养分物质含量和较低的Fe2+/Fe3+比。粗根孔周围土壤具有较高的磷酸酶活性,而细根孔周围具有较高的β-葡糖苷酶活性和脲酶活性。综合比较,人工湿地构建初期,径级较大秸秆腐烂后形成的粗根孔发挥着更高的水分传导效率和更强的物质截留效应。     

UV-Fenton体系预处理四氢呋喃废水实验研究

采用UV-Fenton体系预处理四氢呋喃废水,实验结果表明,pH值、反应时间、Fe2+和H2O2投加量等因素对处理效果有较大的影响。实验确定的最佳反应条件为:原水pH=5,Fe2+投加量2.5 mmol/L,H2O2投加量12 mmol/L,反应时间90 min,连续曝气,在此条件下,COD去除率可达85%左右。经UV-Fenton体系处理后,废水的B/C值由0.16增至0.47,可生化性提高,可满足后续生化处理的要求。