Effects of multiple antibiotics on greenhouse gas and ammonia emissions during swine manure composting

Environmental Science and Pollution Research - Antibiotics are commonly used in intensive farming, leading to multiple antibiotic residue in livestock waste. However, the effects of multiple...     

硝态氮及碳源浓度对A-AAO工艺厌氧释磷影响的研究

为进一步提高A-AAO工艺的厌氧释磷效率,本文以稳定运行A-AAO工艺的污泥为研究对象,考察碳源浓度和污泥回流液硝态氮浓度对厌氧释磷速率的影响。研究结果表明:污泥回流液硝氮浓度越高,厌氧释磷速率越缓慢,且最大释磷量也较低,硝氮浓度从0 mg/L增加到20 mg/L时,释磷速率从0.150 mg TP/(gMLVSS·min)降低到0.103 mgTP/(gMLVSS·min),最大释磷量也从23.95 mg/L减少到15.97 mg/L。碳源浓度显著影响了厌氧区最大释磷量,进水碳源浓度(以乙酸钠投加计算)分别为100,200和300 mg/L,最大释磷总量分别为10.59 mg/L,19.62 mg/L及25.48 mg/L。     

Fate of pathogenic microorganisms and indicators in secondary activated sludge wastewater treatment plants

This study was undertaken to investigate the removal of pathogenic microorganisms and their indicators in a laboratory scale biological treatment system that simulated the secondary treatment process of a wastewater treatment plant (WWTP). Four groups of microorganisms including bacteria, viruses, protozoa and helminths as well as the selected indicators were employed in the investigation. The results demonstrated that approximately 2-3 log10 removal of the microbial indicators was achieved in the treatment process. The log removal of Clostridium perfringens spores was low due to their irreversible adsorption to sludge flocs. The laboratory treatment system demonstrated a similar removal capability for Escherichia coli and the bacterial indicators (total coliforms, enterococci and particles <2.73 microm/L). The MS-2 bacteriophage, measured as a viral indicator, showed a lower removal than poliovirus, which may be considered as a worst case scenario for virus removal. The results of using particle profiling as an indicator for protozoa and helminths appeared to be inaccurate. The removal performance for bacterial and protozoan pathogens and their indicators in a full scale WWTP and the laboratory treatment system was compared.     

通风控制方式对动物粪便堆肥过程中氮、磷变化的影响

以动物园内的动物粪便和水杉落叶为原料,分别采用时间-温度联合控制(Ⅰ号堆体)、时间控制(Ⅱ号堆体)的强制通风控制方式进行堆肥试验,考察了2种强制通风控制方式对动物粪便堆肥过程中氮、磷元素变化的影响.研究结果表明,经过51d的堆肥化以后,Ⅰ、Ⅱ号堆体的NH4 -N平均含量分别从0.95 g·kg-1和0.78 g·kg-1下降到0.36 g·kg-1和0.62 g·kg-1,NO3--N平均含量分别从152mg·kg-1和120mg·kg-1增加到351 mg·kg-1和243 mg·kg-1.由于"浓缩效应",堆肥过程中TN、TP、速效磷的含量均有所增加,Ⅰ、Ⅱ号堆体的TN平均含量分别从16.05 g·kg-1和15.71 g·kg-1增加到19.70 g·kg-1和21.41 g·kg-1,TP平均含量分别从8.17 g·kg-1和8.23 g·kg-1增加到9.38 g·kg-1和9.62 g·kg-1,速效磷平均含量分别从1.83 g·kg-1和1.99 g·kg-1增加到2.81 g·kg-1和3.57 g·kg-1.统计分析结果表明,这2种强制通风控制方式对堆肥过程中速效磷含量变化有着显著的影响(p=0.002),但对其它指标(C/N比、NH4 -N、TN、NO3--N、TP)含量变化的影响却不显著(p＞0.05).     

Effects of phosphorus and nitrogen limitation on PHA production in activated sludge

The e ects of phosphorus and nitrogen limitation on polyhydroxyalkanoate (PHA) production and accumulation by activated sludge biomass with acetate as a carbon source were investigated. Pre-selected influent carbon-phosphorus (C:P, W/W) of 100, 160, 250, 500 and 750, and carbon-nitrogen (C:N, W/W) of 20, 60, 100, 125 and 180 were applied in the phosphorus limitation experiments and the nitrogen limitation experiments, respectively. The maximum PHA accumulation up to 59% of the cell dry weight with a PHA productivity of 1.61 mg PHA/mg COD consumed was observed at the C:N 125 in the nitrogen limitation experiment. This value was much higher than that obtained in previous studies with a normal substrate feeding. The study showed that activated sludge biomass would produce more polyhydroxybutyrate than polyhydroxyvalerate under the stress of nutrient limitation, especially under phosphorus limitation conditions. The experimental result also indicated that both phosphorus and nitrogen limitation may cause sludge bulking.     

Bulking sludge for PHA production:Energy saving and comparative storage capacity with well-settled sludge

Two acetate-fed sequencing batch reactors (SBR) were operated under an aerobic dynamic feeding (ADF) model (SBR #2) and with anaerobic phase before aerobic phase (SBR #1) to select mixed cultures with a high polyhydroxyalkanoates (PHA) storage response. Although kinetic selection based on storage response should bring about a predominance of floc-formers, a bulking sludge with storage response comparable to well-settled sludge was steadily established. An anaerobic phase was introduced before the aerobic phase in the ADF model to improve the sludge settleability (SBR #1), however, due to the consequent increased feast/famine ratio, the performance of SBR #1, in terms of both the maximum PHB (polyhydroxybutyrate) cell content and ΔPHB, was lower than that of SBR #2. SBR #2 gradually reached a steady state while SBR #1 failed suddenly after 50 days of operation. The maximum specific substrate uptake rate and storage rate for the selected bulking sludge were 0.4 Cmol Ac/(Cmol X.hr) and 0.18 Cmol Ac/(Cmol PHB.hr), respectively, resulting a yield of 0.45 Cmol PHB/(Cmol Ac) in SBR #2 in the culture enrichment phase. A maximum PHB content of 53% of total suspended solids and PHB storage rate of 1.36 Cmol Ac/(Cmol PHB.hr) was achieved at 10.2 hr in batch accumulation tests under nitrogen starvation. The results indicated that it was feasible to utilize filamentous bacteria to accumulate PHA with a rate comparable to well-settled sludge. Furthermore, the lower dissolved oxygen demand of filamentous bacteria would save energy required for aeration in the culture enrichment stage.     

人类活动对黄土高原生态环境及现代气候变化的影响

本文简要阐明人类活动对黄土高原生态环境和现代气候变化的影响。重点分析了黄土高原69个气象台站40年来(1951-1969年)气温、降水变化趋势。结果表明:黄土高原的平均气温从50年代以来不断升高,降水持续减少。升温幅度较大的地区多在干旱区的新兴大、中工业城市。并找出了人口增减对气温影响的关系。     

生物膜微环境和传质现象研究进展

生物膜法污水处理工艺对污染物的降解去除主要依赖活性生物膜,研究生物膜的结构和传质特性是揭示反应机理和提高反应器处理效率的重要手段.综述了近年来国外在生物膜微环境和微观传质过程中的研究进展,包括对生物膜微观结构的解析、膜内不同菌系的分布特征及其功能以及生物膜的传质现象和数学模型.在此基础上,提出了生物膜研究领域今后应开展的研究方向.     

Biosynthesis of polyhydroxyalkanoate by Gamma proteobacterium WD-3 from volatile fatty acids

The production of copolymers of poly-β-hydroxyalkanoates (PHA) is generally a high cost process. To reduce the production costs, inexpensive carbon sources such as volatile fatty acids (VFAs) from acidified wastewater can be used. Therefore, isolation of bacterial strains that can produce PHA copolymers using VFAs as a sole carbon source would be a beneficial alternative. In this study, a strain of PHA accumulating bacterium was isolated from the wastewater treatment plant of a soybean processing facility in Harbin. The strain was identified as γ-proteobacterium according to its 16S rDNA information and was originally named as strain WD-3. The strain accumulated a mass of PHA up to 45% of its dry cell weight when it was cultured under the optimum fermentation condition in this study when butyrate was used as the carbon source. In addition, WD-3 could synthesize PHA copolymers of poly-hydroxybutyrate and poly-hydroxyvalerate (PHV) either from C-even substrates or from C-odd substrates, and one-third of the copolymer was PHV. Results from this study demonstrated that small molecule organic acids can be used by the strain of WD-3 as the carbon source for growth and PHA production. The maximum PHA yield in the study was 0.45 g g⁻¹ dry cell.     

物化强化预处理对化工园区废水中典型污染物转化的影响

以江苏省某化工园区污水处理厂的原水为研究对象,分别采用臭氧氧化、铁碳微电解、Fenton氧化3种物化法对其进行强化预处理,并运用GC-MS技术对典型污染物进行了分析。实验结果表明:臭氧氧化、Fenton氧化、铁碳微电解3种物化法在最佳条件下对COD的去除率分别为8.0%,51.3%,45.6%;在提高可生化性方面,臭氧氧化法效果最好,使废水的BOD_5/COD从0.112提高到0.184,Fenton氧化法和铁碳微电解法的BOD_5/COD分别为0.150和0.123;经物化预处理后,废水中的环状物质会出现开环,同时直链物质增多,但苯环、脂类及杂环等难生物降解物质依然存在;若要单纯提高废水的可生化性,建议选用臭氧氧化法;若对去除COD及提高可生化性皆有要求,建议选用铁碳微电解法。