A comparative evaluation of wet digestion and dry ashing methods for the determination of some major and minor nutrients in composted manure

The analytical results of 53 manure samples determined by wet digestion and dry ashing procedures were compared in order to evaluate their relative suitability for recovering different nutrient elements in manure and manure compost. Wet digestion recovered greater amounts of phosphorus (P), potassium (K), calcium (Ca), manganese (Mn), and zinc (Zn) in more samples than dry ashing. Nutrient contents in the samples were highly variable, with coefficients of variation (CV) ranging from 38% for magnesium (Mg) to 161% for copper (Cu) analyzed by the wet digestion procedure, and from 47% to 138% for Mg and Cu analyzed by the dry ashing procedure. The mean values of P, K, Ca, Mn, and Zn averaged for the 53 samples were significantly higher using wet digestion than dry ashing procedure, but both procedures recovered comparable amounts of iorn (Fe), Mg, and Cu. Correlations analysis between both procedures for each element showed reasonable to fair agreements for Ca (R ²?=?0.93), K (R ²?=?0.93), P (R ²?=?0.90), Mg (R ²?=?0.84), Fe (R ²?=?0.87), Mn (R ²?=?0.73), and Cu (R ²?=?0.66), but poor agreement for Zn (R ²?=?0.44). The low agreement between procedures for Zn suggests that wet digestion, which gave a higher recovery, should be a preferred procedure for analyzing Zn in manures.     

九龙江流域规模化养猪场砷污染状况调查

对九龙江流域规模化养猪场猪饲料、沼气出液和猪粪中砷的含量进行了测定。猪饲料中砷的含量范围为0.50～7.72mg·kg-1,平均值为3.49mg·kg-1;沼气出液中砷的含量范围为0.47～56.13μg·L-1,平均值为13.45μg·L-1;猪粪中砷的含量范围为0.32～114.46mg·kg-1,平均值为13.45mg·kg-1。同一养猪场,小猪猪粪中的砷含量一般高于大猪和母猪猪粪;沼气出液和猪粪中的砷含量具有一定的相关性。由估算知,养猪场向九龙江流域年排放的砷总量约为821kg。9家养猪场中有2家猪粪和1家沼气出液中砷的含量相对较高,生态风险等级较高,已超过国家相应标准。总之,应该加强养猪业的管理,以防止养猪场对九龙江流域造成砷污染。     

碳酸盐岩山地土壤施用有机肥的溶蚀作用探讨

选择碳酸盐岩山地常见耕植、未耕植土层,通过概化制作为系列模拟柱试验土层,按当地正常施肥方法,向土层定量施入有机肥并浇灌及控制其它相关条件变化,再定期观测预埋土层不同深度碳酸岩石片的溶蚀量和土层其它指标的变化,作了施用有机肥的土中碳酸岩石溶蚀变化研究。结果揭示,在未耕植红黏土表层施用有机肥,大大减弱了土中碳酸岩石的溶蚀作用,且减弱程度随土深加大而降低。但对其下伏碱性岩粉层而言,施肥又引起了溶蚀量的微小增加变化;另在耕植土表层施用有机肥,对其土中碳酸岩石的溶蚀作用改变不大,且无论施肥与否溶蚀作用随土深加大又略显增大变化。而其下部红黏土中碳酸岩石的溶蚀量要远大于耕植土中的溶蚀量,并受施肥的影响较小。表明,农业施肥对未耕植土土中包被、包裹的碳酸岩石溶蚀影响较大,对下伏碱性岩粉层的层中、层下碳酸岩石的溶蚀影响较小。同时,施肥对耕植土土中、土下碳酸岩石的溶蚀影响不大。人类可采取禁令开垦较薄土层措施,来有效规避耕作施肥对土中碳酸岩石溶蚀作用的抑制,减少反石漠化的不利因素。此将为丰富碳酸盐岩山地成土演化理论和石漠化灾害的防治提供依据。     

高浓度有机牧场养牛废水处理工程的设计与运行

针对南昌某有机牧场的养牛废水悬浮物、有机物、氨氮浓度高等特点,采用厌氧消化-UASB-SBR组合处理工艺,进水COD为18～20 g/L、NH3-N为410～510 mg/L、SS为4～6 g/L,通过工程调试和运行后,出水COD、NH3-N和SS去除率分别为98.1%、76.1%、97.5%,各指标均达到了《畜禽养殖业污染物排放标准》(GB 18596—2001)的要求。对南方地区的养殖场废水处理工程具有一定的参考价值。     

Effects of adding biochar on tetracycline removal during anaerobic composting of swine manure

Residual antibiotics in manure pose a potential threat to public and ecological health when the manure is released to the environment via land application of manure as fertiliser. Anaerobic composting has the potential to decrease antibiotic concentrations prior to land application. We therefore investigated the degradation of the antibiotics tetracycline (TC) and oxytetracycline (OTC) during anaerobic composting under different conditions. All composting treatment conditions were able to effect significant decreases in the antibiotic concentrations, though without biochar antibiotic residues remained. TC and OTC were removed more efficiently when the compost was treated at 55°C than treatments at 35°C or 25°C. Adding biochar significantly and rapidly decreased the antibiotic concentrations in the compost samples. After 15 days of treatment with biochar at 55°C, 100% of TC and OTC had been removed from the manure. The marked ability of biochar to remove the antibiotics was primarily attributed to adsorption of TC and OTC by the biochar. However, the addition of biochar may also have altered the microbial community structures within the compost and accelerated microbial degradation of the antibiotics.     

Short term effects of copper, sulfadiazine and difloxacin on the anaerobic digestion of pig manure at low organic loading rates

Antibiotics of inorganic and organic origin in pig manure can inhibit the anaerobic process in biogas plants. The influence of three frequently used antibiotics, copper dosed as CuSO₄, sulfadiazine (SDZ), and difloxacin (DIF), on the anaerobic digestion process of pig manure was studied in semi-continuous experiments. Biogas production recovered after every Cu dosage up to a sum of 12.94 g Cu kg⁻¹ organic dry matter (ODM), probably due to Cu precipitation following the formation of sulphide from sulphate. Complete inhibition was found at the very high Cu concentration of 19.40 g Cu kg⁻¹ ODM. Inhibitory effect of SDZ and DIF was observed at concentrations as high as 2.70 g kg⁻¹ ODM and 0.54 g kg⁻¹ ODM, respectively. It seems very unlikely that the antibiotics tested would inhibit the anaerobic process in a full-scale biogas plant.     

Anaerobic digestion of chicken feather with swine manure or slaughterhouse sludge for biogas production

Biogas production from anaerobic digestion of chicken feathers with swine manure or slaughterhouse sludge was assessed in two separate experiments. Ground feathers without any pre-treatment were added to 42-L digesters inoculated with swine manure or slaughterhouse sludge, representing 37% and 23% of total solids, respectively and incubated at 25 °C in batch mode. Compared to the control without feather addition, total CH₄ production increased by 130% (P < 0.001) and 110% (P = 0.09) in the swine manure and the slaughterhouse sludge digesters, respectively. Mixed liquor NH₄N concentration increased (P < 0.001) from 4.8 and 3.1 g/L at the beginning of the digestion to 6.9 and 3.5 g/L at the end of digestion in the swine manure and the slaughterhouse sludge digesters, respectively. The fraction of proteolytic microorganisms increased (P < 0.001) during the digestion from 12.5% to 14.5% and 11.3% to 13.0% in the swine manure and the slaughterhouse sludge digesters with feather addition, respectively, but decreased in the controls. These results are reflective of feather digestion. Feather addition did not affect CH₄ yields of the swine manure digesters (P = 0.082) and the slaughterhouse sludge digesters (P = 0.21), indicating that feathers can be digested together with swine manure or slaughterhouse sludge without negatively affecting the digestion of swine manure and slaughterhouse sludge.     

混合堆肥过程中自由空域(FAS)的层次效应及动态变化

城市污泥、猪粪混合堆肥试验表明:升温期和高温期FAS分别为42.3%、26.2%,在这2个堆肥期内堆体上部的FAS明显高于下部,堆体内的空气能满足微生物的需求;降温期FAS为52.4%,堆体上部的FAS高于中部,中部高于下部,FAS呈明显的层次效应;腐熟期FAS为54.7%,FAS的层次效应减弱,堆体上部和中部的通气性明显好于下部.不同堆肥期剖面上下部FAS的差异由大到小分别为:降温期>高温期>后熟期>升温期;堆体内FAS由高到低为:上部>中部>下部.FAS随时间的变化满足二级反应动力学方程.     

韩国绿色种养循环农业发展概况与经验启示

联合国将碳中和视为当今世界最为紧迫的任务,而农业是温室气体排放最多的产业之一,各国相继出台政策积极开展农业农村减排工作。韩国自2012年开始逐渐减少海洋粪污排泄量,并大力实行绿色种养循环农业,解决本国内畜禽粪污问题。韩国作为中国的重要海上邻国,不论是从研究借鉴角度抑或生态系统共享角度,了解其环境保护政策都是十分必要的。本文从韩国实施的主要政策、各地区农地养分收支现状、代表性运营模式案例、政策关注焦点等方面介绍韩国绿色种养循环农业的发展概况,结合中国绿色种养循环农业现状开展研究。提出三点政策建议：第一,进一步完善畜禽粪污资源化利用机具补贴辅助管理系统,提高系统在农户中的普及率;第二,提高全民环保意识的同时,政府的角色不应局限自上而下的引导型,应该积极促进种植户和养殖户间的自发组织,并大力提倡吸纳社会资本,集结社会各方力量;第三,促进绿色种养循环农业产品的商品化和品牌化,从而调动农户参与绿色种养循环农业的积极性。     

阻碍我国有机肥推广的经济成因分析

对有机肥施用领域的各个环节进行了梳理和分析,认为有机肥经济正外部性未能内部化和监管体系薄弱是影响有机肥推广的两个主要原因,其中经济正外部性未能内部化增加了农户和企业在有机肥使用或生产上的投入成本,从根本上遏制了使用或生产有机肥的积极性,而监管体系的薄弱进一步缩减了有机肥的利润空间,因此阻碍有机肥推广的根本成因在于有机肥经济正外部性未能内部化,即经济激励的缺失。并据此提出了相应的解决措施。