蒸汽爆破对污泥和餐厨垃圾联合厌氧消化的促进效果

鉴于蒸汽爆破（简称"汽爆"）预处理对污泥和餐厨垃圾联合厌氧消化的影响还鲜有报道,为探讨汽爆预处理对污泥和餐厨垃圾联合中温厌氧消化的促进效果及经济可行性,利用小型发酵罐在35℃下开展了未预处理污泥和餐厨垃圾联合消化、汽爆污泥单独消化、汽爆污泥和餐厨垃圾联合消化的试验,并进行能耗分析.结果表明,未预处理污泥与餐厨垃圾联合消化阶段,VS（挥发性固体）去除率为33.9%,沼气产率为311.0 mL/g（以投料VS计）;汽爆污泥单独消化阶段,VS去除率和沼气产率均略高于未预处理污泥与餐厨垃圾联合消化阶段,但反应器ρ（NH₄+-N）过高,影响产气稳定性,沼气φ（CH₄）较低.汽爆污泥与餐厨垃圾联合消化阶段,VS去除率和沼气产率分别达到49.5%和420.5 mL/g,显著优于未预处理联合消化阶段.能耗分析表明,预处理的升温过程使汽爆预处理整体能耗偏高,但若能有效回收70%的热量,则汽爆预处理可提高污泥-餐厨垃圾联合中温厌氧消化工艺3.34 kW·h/t（以污泥量计）的能量产率.研究显示,汽爆预处理可提高污泥和餐厨垃圾联合中温厌氧消化工艺35.2%的沼气产率,但由于预处理能耗较高,预处理过程中热能的有效回收是汽爆预处理应用于污泥和餐厨垃圾联合中温厌氧消化经济可行的关键.      

正确引导有机食品产业的发展

论述了有机食品开发中存在的问题，提出了发展有机食品产业的建议。     

The Role of the Concept of the Natural (Naturalness) in Organic Farming

Producers, traders, and consumers oforganic food regularly use the concept of thenatural (naturalness) to characterize organicagriculture and or organic food, in contrast tothe unnaturalness of conventional agriculture.Critics sometimes argue that such use lacks anyrational (scientific) basis and only refers tosentiment. In our project, we made an attemptto clarify the content and the use of theconcepts of nature and naturalness in organicagriculture, to relate this conception todiscussions within bioethical literature, andto draw the implications for agriculturalpractice and policy.Qualitative interviews were executed with arange of people in the field of organicagriculture and with consumers of organicproducts, on the basis of a list of statementsabout the meaning of the concept of naturalnessformulated by the authors. Based on the resultsof the interviews, we distinguished 3 aspectsof the concept of naturalness: natural as theorganic (life processes), natural as theecological, and natural as referring to thecharacteristic nature of an entity. We relatedthese conceptual aspects to three mainapproaches within the field of organicagriculture: the no chemicals approach, theagro-ecological approach, and the integrityapproach. It became clear that these approachescan also be recognized in the change ofattitude of farmers as they convert fromconventional to organic agriculture, and in theattitudes of consumers of organic foodproducts.We conclude that the idea of ``naturalness' canbe used to characterize organic agriculture andto distinguish it from conventionalagriculture, but only if naturalness not onlyrefers to not using chemicals but also toecological principles and respect for theintegrity of life. Thus perceived, theprinciple of naturalness can also serve as aguide to future developments in the field oforganic agriculture. As part of the holocentricethics of organic farming the value ofnaturalness has three dimensions: a cognitiveone, an emotive one, and a normative one.     

On vegetarianism,morality, and science: A counter reply

I recently took issue with Kathryn George's contention that vegetarianism cannot be a moral obligation for most human beings, even assuming that Tom Regan's stringent thesis about the equal inherent value of humans and many sentient nonhumans is correct. I argued that both Regan and George are incorrect in claiming that his view would permit moral agents to kill and eat innocent, non-threatening rights holders. An unequal rights view, by contrast, would permit such actions if a moral agent's health or life is at stake. I then argued that current nutritional research does not support Professor George's claim that some wealthy adult males (and many fewer wealthy women) are the only persons whose health does not require the consumption of nonhuman animals and their products. In her 1992 response to my critique, George did not address my moral argumentation. She concentrated her entire paper on a wholesale rejection of my discussion of nutrition. Although she now takes a somewhat more moderate position on who can safely contemplate strict vegetarianism, she still believes that most people are not in a position to follow such a diet. In my counter-reply, I argue that her rejection is based upon numerous distortions, omissions, and false charges of fallacy. She even devotes a substantial section of her paper to criticizing me for saying the opposite of what I actually wrote. As I did in my earlier paper, I cite current research, including George's own preferred source on the topic of vegetarianism, to support my view. I conclude that Professor George has still not shown that for most human beings it is dangerous to follow a diet that omits nonhuman animals and their products. Moral agents who take the rights of humansand nonhumans seriously will find vegetarianism well worth considering.     

Effects of mixture ratio on anaerobic co-digestion with fruit and vegetable waste and food waste of China

The biochemical methane potentials for typical fruit and vegetable waste (FVW) and food waste (FW) from a northern China city were investigated, which were 0.30, 0.56 m3 CH4/kgVS (volatile solids) with biodegradabilities of 59.3% and 83.6%, respectively. Individual anaerobic digestion testes of FVW and FW were conducted at the organic loading rate (OLR) of 3 kg VS/(m3 day) using a lab-scale continuous stirred-tank reactor at 35°C. FVW could be digested stably with the biogas production rate of 2.17 m3/(m3 day) and methane production yield of 0.42 m3 CH4/kg VS. However, anaerobic digestion process for FW was failed due to acids accumulation. The effects of FVW: FW ratio on co-digestion stability and performance were further investigated at the same OLR. At FVW and FW mixing ratios of 2:1 and 1:1, the performance and operation of the digester were maintained stable, with no accumulation of volatile fatty acids (VFA) and ammonia. Changing the feed to a higher FW content in a ratio of FVW to FW 1:2, resulted in an increase in VFAs concentration to 1100–1200 mg/L, and the methanogenesis was slightly inhibited. At the optimum mixture ratio 1:1 for co-digestion of FVW with FW, the methane production yield was 0.49 m3 CH4/kg VS, and the volatile solids and soluble chemical oxygen demand (sCOD) removal efficiencies were 74.9% and 96.1%, respectively.     

餐厨垃圾好氧生物处理菌株的选育

文章以枯草芽孢杆菌、巨大芽孢杆菌等10株细菌为出发菌株,以耐高温、生长速度快、生物安全性、生物拮抗性以及产酶能力为筛选原则,从中筛选得到4株细菌,分别为:地衣芽孢杆菌(Bacillus licheniformis,TKFW1003)、巨大芽孢杆菌(Bacillus megaterium,TKFW1005)、纳豆芽孢杆菌(Bacillus natto,TKFW1102)、枯草芽孢杆菌(Bacillus subtilis,TKFW1108)。然后将筛选得到的4株细菌按10%的比例添加到30 L固态发酵罐中,再添加10%的麸皮和50%的水为辅料,对餐厨垃圾进行固态发酵处理。最后将固态发酵结束后得到的产品取出烘干粉碎,经检测:经好氧微生物处理后得到的产品,其有效活菌数、有机质含量、水分含量及蛔虫卵死亡率等指标均达到了农业部农用有机肥标准,此法实现了餐厨垃圾的无害化、资源化、减量化处理,具有生产成本低、无二次污染、可操作性强等优点。     

大连沿海常见海产品PFOS和PFOA的暴露水平调查

文章应用液相色谱-质谱分析方法,对2009年春季大连沿海常见海产品体内PFOS和PFOA的暴露水平进行了调查。鱼、蟹、乌贼和海胆肌肉中PFOS的平均暴露水平分别为0.40 ng/g,0.07 ng/g,0.09 ng/g及0.12 ng/g(湿重),而PFOA的平均暴露水平分别为0.06ng/g,0.01 ng/g,0.06 ng/g及0.10 ng/g(湿重)。鱼类肝脏中PFOS和PFOA的平均暴露水平分别为0.90 ng/g和0.24 ng/g。调查结果表明,大连沿岸常见海产品体内普遍检测到PFOS和PFOA,并且肝脏中PFOS和PFOA暴露水平均高于肌肉组织。通过比较发现,大连沿岸鱼类样品中PFOS的暴露水平低于美、日等国家的沿岸海域鱼类的暴露水平。     

厦门快速城市化中居民食物C、N、P消费动态

随着城市化进程的不断推进以及城市人口的快速增长,城市人类活动对生态系统的元素循环影响越来越显著,不可持续的家庭消费已成为造成全球环境问题的主要原因,食物元素消费的研究也成为可持续消费的重要研究内容。以厦门市为例,分析了1988-2010年居民食物C、N、P元素消费的变化趋势及特点,探讨与其变化相关的经济、社会因子。研究结果表明:1988-2010年全市食物消费总量不断增加,由49.33万t增长至106.36万t。但是人均食物消费量由321.28 kg/(人.a)降至301.32 kg/(人.a)。厦门市食物C、N、P消费总量均在上升,1988年食物C、N、P消费量分别为10.14、0.64、0.05万t,到2010年食物C、N、P消费量分别为17.29、1.21、0.11万t,分别增长了70.45%、88.91%、117.11%,与此同时人均食物C、N、P消费量却在降低,其变化趋势与人均食物消费量的变化趋势接近,但并不完全一致,其中下降幅度最大的为人均食物C消费量,下降了24.92%,其次是人均食物N消费量下降了16.79%,下降幅度最小的为人均食物P消费量降低了4.37%。这主要是由于食物消费结构发生变化所致,粮食在食物C、N、P消费总量中所占比例持续下降,禽畜肉、瓜果、鲜蛋、奶制品等在食物C、N、P消费总量中所占比例分别有不同程度的增长,城市家庭食物消费模式由"以粮食为主"向"以粮食和肉类、蔬菜为主"转变。通过将相关经济、社会因子与居民食物C、N、P消费量进行相关性分析表明,人均GDP、恩格尔系数、人均可支配收入、食物消费支出、食物价格指数、大学人口比重、平均家庭人口数,与食物C、N消费量均相关,与食物P消费量相关性不显著。     

食品垃圾好氧降解过程中挥发性有机物(VOCs)排放特征

采用实验室模拟方法,研究了混合食品垃圾(FW)及以橙子、生菜、土豆和西红柿为代表的4种植物性易降解有机垃圾组分好氧降解过程中排放出来的117种挥发性有机物(VOCs)的排放量和组成特征.结果表明,混合食品垃圾好氧降解过程中VOCs总排放量为951.80mg·kg-1,主要为有机硫、含氧化合物和萜烯,分别占VOCs总排放量的43.1%、53.3%和2.1%.橙子、生菜、土豆和西红柿4种植物性易降解有机垃圾好氧降解过程中VOCs的总排放量分别为12736.72、118.67、57.40和228.08mg·kg-1,主要成分均为含氧化合物和萜烯;含氧化合物分别占橙子、生菜、土豆和西红柿4种植物性易降解有机垃圾VOCs总排放量的13.5%、80.9%、85.9%和79.5%,萜烯分别占4种植物性易降解有机垃圾VOCs总排放量的86.5%、16.6%、8.2%和15.6%.     

造纸污泥和餐厨垃圾混合发酵联产氢气和甲烷试验

采用联产氢气和甲烷复合工艺,对造纸污泥和餐厨垃圾进行中温-高温混合厌氧消化,通过设计两种物料的不同配比(质量比,以VS计),研究了不同比例混合的物料联产氢气和甲烷的性能.试验结果表明,造纸污泥和餐厨垃圾混合比例为2:2的反应器总气体产率最高,达496.78mL·g-1(其中,氢气64.48mL·g-1,甲烷432.3mL·g-1,均以VSfed计,下同),其VS去除率也最高,达41.33%,在反应30h后和产甲烷18d后分别完成了80%的氢气产量和甲烷产量,而单纯造纸污泥总气体产率为144.99mL·g-1,单纯餐厨垃圾总气体产率为80.4mL·g-1.综合氢气和甲烷产率、产气速率、VS去除率等指标发现,造纸污泥和餐厨垃圾混合发酵联产氢气和甲烷的最佳配比为2:2.