Overview of on-farm bioremediation systems to reduce the occurrence of point source contamination

Contamination of ground and surface water puts pressure on the use of pesticides. Pesticide contamination of water can often be linked to point sources rather than to diffuse sources. Examples of such point sources are areas on farms where pesticides are handled and filled into sprayers, and where sprayers are cleaned. To reduce contamination from these point sources, different kinds of bioremediation system are being researched in various member states of the EU. Bioremediation is the use of living organisms, primarily microorganisms, to degrade the environmental contaminants into less toxic forms. The systems available for biocleaning of pesticides vary according to their shape and design. Up till now, three systems have been extensively described and reported: the biobed, the Phytobac and the biofilter. Most of these constructions are excavations or different sizes of container filled with biological material. Typical overall clean-up efficiency exceeds 95%, realising even more than 99% in many cases. This paper provides an overview of the state of the art of these bioremediation systems and discusses their construction, efficiency and drawbacks.     

Degradation of isoproturon and bentazone in peat- and compost-based biomixtures

BACKGROUND: The composition and properties of a biomixture used in a biobed are decisive for pesticide sorption and degradation. This study was performed to investigate the capability of compost‐based substrates in mixtures with citrus peel and vine branch straw and peat‐based substrates in mixtures with soil and vine branch straw at different levels in order to degrade isoproturon and bentazone. RESULTS: Dissipation and mineralisation rates of both pesticides were determined, and metabolic activity was followed as respiration. Compost‐based substrates showed faster pesticide dissipation in the presence of lignocellulosic materials, as in garden compost and vine branch straw. The increasing content of vine branch straw in peat‐based substrates does not seem to affect dissipation of the parent compounds. Low mineralisation rate was observed in all treatments. CONCLUSION: Higher pesticide degradation was observed in the lignocellulosic substrates, probably because of the development of lignin‐degrading microorganisms which have shown to be robust and are able to degrade recalcitrant pesticides. Copyright © 2010 Society of Chemical Industry     

发酵床养猪过程中垫料P素和K素物质流分析

选取3种垫料(40%稻壳+60%菌糠、40%稻壳+60%锯木屑、40%稻壳+60%酒糟)为研究对象,分别在育肥猪进栏前和出栏后对垫料和表层土壤进行采样分析,采用物质流分析的方法分析了一个养猪周期内3种垫料TP和TK的损失途径。结果表明:P素在发酵床养殖过程中主要的损失途径为猪采食与淋溶损失,总损失量分别为(FJ:40%稻壳+60%菌糠组合)15.69 kg、(FD:40%稻壳+60%锯木屑组合)16.61 kg、(FW:40%稻壳+60%酒糟组合)14.37 kg;而3种发酵床分别有(FJ)80.74 kg、(FD)52.48 kg、(FW)84.65 kg的总P库存在垫料中,75%~85%的P素会滞留在垫料中,损失率均超过14%。K素的主要损失途径也为猪采食与淋溶损失,总损失量分别为(FJ)45.95 kg、(FD)33.95 kg、(FW)63.95 kg;总库存的K素分别为(FJ)158 kg、(FD)107 kg、(FW)136 kg,68%~78%的K素会留存在垫料中,损失率均超过22%。养殖过后发酵床下部表层土壤会出现P素和K素累积现象,为了防止元素通过淋溶作用渗漏损失,建议发酵床垫料厚度要超过50 cm。     

日粮添加地衣芽孢杆菌对仔猪发酵床垫料理化性质及微生物群落的影响

试验旨在研究发酵床饲养模式下,猪日粮中添加地衣芽孢杆菌对发酵床的理化性质和微生物群落的影响。分别饲喂基础饲粮(对照组)、基础饲粮+杆菌肽锌+硫酸黏杆菌素(抗生素组)和基础日粮+地衣芽孢杆菌(益生菌组)的试验日粮。结果表明:饲粮中添加地衣芽孢杆菌能显著提高发酵床垫料蛋白酶活性(P0.05),对垫料脲酶活性和铵态氮含量无显著影响(P0.05);试验第15 d时,抗生素组的垫料放线菌数量显著低于对照组(P0.05);第35 d时,益生菌组的芽孢杆菌数量显著高于其他组(P0.05);第49 d时,益生菌组的芽孢杆菌数量显著高于抗生素组(P0.05),抗生素组的葡萄球菌数量比对照组显著降低(P0.05);益生菌组、抗生素组的大肠杆菌低于对照组,抗生素组的细菌总数、芽孢杆菌数量低于对照组,但差异均不显著(P0.05),饲粮抗生素一定程度上减少了垫料益生菌,但能有效减少垫料病原菌;各处理组间,垫料微生物DGGE的香农-威纳指数、均匀度均无显著差异(P0.05)。饲用地衣芽孢杆菌显著增加垫料中芽孢杆菌分布数量,提高垫料中垫料蛋白酶活,没有显著影响垫料细菌多样性指数,一定程度上提高粪便原位降解效率。     

Atrazine dissipation in a biobed system inoculated with immobilized white-rot fungi

Due to environmental concerns about accumulation of the herbicide atrazine in food products and water reservoirs, there is a need to develop safe and economical methods for its dissipation. The main aim of this study was to evaluate atrazine dissipation in a biobed system inoculated with immobilized white-rot fungi in a pelletized support (PS). All fungal isolates evaluated were efficient in colonizing the surface and inner parts of the PS, with no differences observed in the colonization over the assay. The highest atrazine dissipation (93%) was observed for Stereum hirsutum Ru-104 after 60 days of incubation. In contrast, the lowest atrazine dissipation (78%) was observed for the non-inoculated biobed over an identical period. Trametes versicolor HL01 was involved in the highest phenoloxidase activity. This activity indicates that inoculated and non-inoculated biobeds were biologically active over the incubation period. A high respiration rate in the biobed was observed when it was inoculated with S. hirsutum Ru-104. Inoculation of fungi on PS systems may be a coadjutant in the increase of fungal efficiency in enzymatic production.     

Capacity of model biobeds to retain and degrade mecoprop and isoproturon

Biobeds are used to increase the adsorption and degradation of pesticide spillage on sites used for mixing and loading and for cleaning of sprayers. The adsorption and the rate of degradation of 14C-labelled isoproturon and mecoprop (MCPP) at concentrations from 0.0005 to 25 000 mgkg(-1) were determined in biobed soil. Further leaching of the two herbicides was determined in a model biobed with a surface area of 2 m2. The biobed material showed enhanced ability to adsorb the two herbicides. Kd was 5.2 litre kg(-1) for isoproturon and 1.6 litre kg(-1) for MCPP in biobed material, which is higher than in natural soil. In different experiments with natural soil, Kd ranges from 0.07 to 0.6 litrekg(-1) for MCPP and from 1.5 to 4.6 litre kg(-1) for isoproturon in soils with varying organic carbon content. Degradation of MCPP was rapid at concentrations from 0.0005 to 500 mg kg(-1), delayed at 5000 mg kg(-1), and very slow at 25 000 mg kg(-1). For isoproturon, the relative degradation was most rapid at the lowest concentration and decreasing with increasing concentrations. After 120 days, between 55% and 8% 14C was evolved as 14CO2 at concentrations between 0.0005 and 25 000 mg kg(-1). The rate of evolution of 14CO2 indicated that degradation rates at low concentrations were of first-order and at higher concentrations of zero-order. Leaching of MCPP and isoproturon was determined in a newly established model biobed during a 2-year period. About 13% of applied MCPP and 1.4% of applied isoproturon leached out during the winter following the first autumn application (worst-case scenario). Leaching was completely prevented when the biobed had a well-developed grass cover and was covered during the winter.     

不同垫料组成对猪用发酵床细菌群落的影响

为了解垫料基质中细菌的群落结构多样性,应用PCR-DGGE技术对发酵床7种不同垫料(锯木屑、稻壳、酒糟、菌糠、醋糟、稻草、稻壳炭)的细菌群落结构进行了研究,根据DGGE指纹图谱,对它们的细菌群落多样性和优势条带进行了分析。结果表明,垫料样品的细菌多样性指数、丰富度均有所不同,酒糟垫料组细菌多样性指数最高,稻草垫料组细菌多样性指数最低。全锯木屑与50%稻壳相似性较高而聚为一类,与50%菌糠次之,与50%稻草的相似性最低。在垫料基质中检测到的菌群主要是节杆菌属(Arthrobacter sp.)、Amaricoccu sp.、马杜拉放线菌属(Actinomadura sp.)、芽孢杆菌属(Bacillales sp.)、梭菌属(Clostridium sp.)、肠杆菌属(Escherichia sp.)、细杆菌属(Microbacterium sp.)、假单胞菌属(Pseudomonas sp.)、红球菌属(Rhodococcus sp.)、葡萄球菌属(Staphylococcus sp.),以及一些未知的菌群。垫料组成是影响发酵床垫料微生物构成的重要因素,稻壳、菌糠作为垫料可部分替代锯木屑,而对发酵床垫料的微生物区系影响较小。     

养猪舍不同发酵床垫料碳素流向及二氧化碳与甲烷排放初探

为了探明发酵床养猪过程碳素流向及二氧化碳与甲烷排放特征,分别选取3种不同原料的发酵床:稻壳+锯木屑(FD)、稻壳+菌糠(FJ)、稻壳+酒糟(FW)作为研究对象,通过垫料采集和静态箱法收集气体,对一个养殖周期内的碳素变化和二氧化碳、甲烷排放量进行测定。结果表明,一个养殖周期结束后,3种发酵床二氧化碳与甲烷的排放总量占碳素总损失的比例分别为41.21%(FJ)、54.12%(FD)、48.27%(FW),是碳素转化的主要形式。3种垫料的二氧化碳排放特点呈现一定的相似性,均在养殖前期与后期各出现1个排放高峰期,后期排放量大于前期;其二氧化碳排放总量具有显著性差异,FD在整个养殖周期内二氧化碳排放量最大,其次是FJ。FJ与FW的甲烷排放特点与二氧化碳相似,均在养殖前期与后期出现两个排放高峰期且排放量大小相近,而FD的甲烷排放集中在前期,后期仅有微弱回升;3种发酵床的甲烷排放总量同样具有显著性差异,一个饲养周期内FW的甲烷排放总量最大,其次是FJ。通过相关性分析发现,3种发酵床二氧化碳与甲烷的排放呈负相关关系,初步表明发酵床存在甲烷氧化成二氧化碳的生物途径。