Batch culture enrichment of ANAMMOX populations from anaerobic and aerobic seed cultures

Discharge of nitrate and ammonia rich wastewaters into the natural waters encourage eutrophication, and contribute to aquatic toxicity. Anaerobic ammonium oxidation process (ANAMMOX) is a novel biological nitrogen removal alternative to nitrification-denitrification, that removes ammonia using nitrite as the electron acceptor. The feasibility of enriching the ANAMMOX bacteria from the anaerobic digester sludge of a biomethanation plant treating vegetable waste and aerobic sludge from an activated sludge process treating domestic sewage is reported in this paper. ANAMMOX bacterial activity was monitored and established in terms of nitrogen transformations to ammonia, nitrite and nitrate along with formation of hydrazine and hydroxylamine.     

Modeling a granule‐based anaerobic ammonium oxidizing (ANAMMOX) process

A mathematical model was developed to describe the anaerobic ammonium oxidation (ANAMMOX) process in a granular upflow anaerobic sludge blanket (UASB) reactor. ANAMMOX granules were cultivated in the UASB reactor by seeding aerobic granules. The granule‐based reactor had a great N‐loading resistant capacity. The model simulation results on the 1‐year reactor performance matched the experimental data well. The yield coefficient for the growth and the decay rate coefficient of the ANAMMOX granules were estimated to be 0.164 g COD g^?1 N and 0.00016 h^?1, respectively. With this model, the effects of process parameters on the reactor performance were evaluated. Results showed that the optimum granule diameter for the maximum N‐removal should be between 1.0 and 1.3 mm and that the optimum N loading rate should be 0.8 kg N m^?3 d^?1. In addition, the substrate micro‐profiles in the ANAMMOX granules were measured with a microelectrode to explore the diffusion dynamics within the granules, and the measured profiles matched the predicted results well. Biotechnol. Bioeng. 2009;103: 490–499. © 2009 Wiley Periodicals, Inc.     

Anaerobic ammonium oxidation in constructed wetlands with bio-contact oxidation as pretreatment

Anaerobic ammonium oxidation (ANAMMOX) may provide an effective nitrogen removal pathway for constructed wetlands with low C/N influent. In a study of domestic sewage treatment, anaerobic ammonium oxidation process was identified in the pilot-scale constructed wetland of a bio-ecological process which was composed of a bio-contact oxidation reactor and a horizontal subsurface flow constructed wetland (CW). To investigate the ANAMMOX establishment in the bio-ecological process, two new CWs (planted and unplanted) were developed to be a control for the pre-existing CW. Under operational conditions of DO 2-3 mg/l, HRT 3.5 h for the bio-contact oxidation reactor, HRT 3 days for CWs, and domestic sewage as influent, the process achieved more than 90% TN removal rate after the ANAMMOX was established. The ANAMMOX bacteria on the media of the constructed wetlands were analyzed by specific polymerase chain reaction (PCR) with ANAMMOX specific primer set AMX818F-AMX1066R. The result of the genetic sequencing showed that the PCR product was related to Candidatus B. anammoxidans (AF375994.1) with 98% sequence similarity. Copy numbers of 16S rRNA gene of ANAMMOX bacteria in the pre-existing CW, the new planted CW and new unplanted CW were 3.47 × 10⁵, 3.02 × 10⁵ and 1.30 × 10⁵, respectively. These results demonstrated that the ANAMMOX process was successfully established and operated consistently in the constructed wetlands with a bio-contact oxidation reactor as a pretreatment, and that vegetation positively affected the growth and enrichment of ANAMMOX bacteria.     

利用生物反应器培养植物细胞的研究进展（Ⅱ）

介绍了当前用于植物细胞培养的生物反应器类型（搅拌式、气升式、转鼓式和鼓泡式生物反应器）及其特点,对各种类型的反应器进行了比较与选择;并进一步介绍了植物细胞固定化培养,提出今后利用反应器大规模培养植物细胞的发展研究方向。     

PVA-alginate immobilized cells for anaerobic ammonium oxidation (anammox) process

The feasibility of an anaerobic ammonium oxidation (anammox) process combined with a cell-immobilization technique for autotrophic nitrogen removal was investigated. Anammox biomass was cultivated from local activated sludge and achieved significant anammox activity in 6 months. The development of a mature anammox biomass was confirmed by fluorescence in situ hybridization (FISH) analysis and off-line activity measurements. The abundance fraction of the anammox bacteria determined by FISH analysis was estimated by software. The anaerobic ammonia oxidizers occupied almost half of the total cells. Additionally, the anammox biomass was granulated as spherical gel beads of 3-4 mm in diameter by using a cell-immobilization technique. The nitrogen removal activity was proved to be successfully retained in the beads, with about 80% of nitrogenous compounds (NH(4) (+), NO(2) (- )and total nitrogen) removed after 48 h. These results offer a promising technique for the preservation of anammox microorganisms, the protection of them against the unfavorable surroundings, and the prevention of biomass washout towards the implementation of sustainable nitrogen elimination biotechnology. This is the first report on the immobilization of anammox biomass as gel beads.     

植物细胞生物反应器培养的研究进展(I)

利用植物细胞大规模悬浮培养生产植物有用代谢产物在近些年来取得了很大发展,但植物细胞悬浮培养的工业化应用受到来自生物及工程技术上的限制.本文针对植物细胞培养的基本特点,详细讨论了与大规模生产有关的工程技术方面的问题,如植物细胞聚集、溶氧及气体成分、流体性能、剪切力对植物细胞培养产生的影响.     

The anaerobic utilisation of cyanide in the presence of sugars by microbial cultures can involve an abiotic process

The degradation of cyanide under anaerobic conditions in the presence of a growing culture of a strain of Klebsiella planticola has been shown to be due to a chemical process dependent upon the presence of a reducing sugar in the medium. The conversion of cyanide to ammonia was independent of any biological factors under these conditions.     

Enhanced denitrifying phosphorous removal in a novel anaerobic/aerobic/anoxic (AOA) process with the diversion of internal carbon source

A novel anaerobic/aerobic/anoxic (AOA) process is proposed to realize denitrifying phosphorous removal in this study, and the characteristic of the AOA process is transferring part of the anaerobic mixed liquor to the post-anoxic zone for providing the carbon source needed for denitrification. The AOA process was operated for 3 months, and the average removal efficiencies of NH4+-N, TN and PO4(3-)-P were 93.0±3.1%, 70.3±2.9% and 87.3±11.8%, respectively. A mass balance analysis indicated that 0.49±0.02 g VSS(-1) d(-1) of PO4(3-)-P and 0.23±0.04 g VSS(-1) d(-1) of NO3--N were simultaneously removed in the anoxic zone, and it is speculated that denitrifying phosphorous removal occurred in the AOA process. Furthermore, 0.24±0.06 g VSS(-1) d(-1) of TN was removed in the aerobic zone via simultaneous nitrification and denitrification (SND). The results demonstrate that the multi-zone structure of the AOA process favors the enhancement of denitrifying phosphorous removal and SND for municipal wastewater treatment.     

Performance of sulfidogenic anaerobic baffled reactor (ABR) treating acidic and zinc-containing wastewater

The applicability of anaerobic baffled reactor (ABR) was investigated for the treatment of acidic (pH 4.5–7.0) wastewater containing sulfate (1000–2000 mg/L) and Zn (65–200 mg/L) at 35 °C. The ABR consisted of four equal stages and lactate was supplemented (COD/SO₄²⁻ = 0.67) as carbon and energy source for sulfate reducing bacteria (SRB). The robustness of the system was studied by decreasing pH and increasing Zn, COD, and sulfate loadings. Sulfate-reduction efficiency quickly increased during the startup period and reached 80% within 45 days. Decreasing feed pH, increasing feed sulfate and Zn concentrations did not adversely affect system performance as sulfate reduction and COD removal efficiencies were within 62–90% and 80–95%, respectively. Although feed pH was steadily decreased from 7.0 to 4.5, effluent pH was always within 6.8–7.5. Over 99% Zn removal was attained throughout the study due to formation of Zn-sulfide precipitate.     

斑块生境中啮齿类和蚁类动物对南方红豆杉地面种子的搬运

南方红豆杉(Taxus chinensis)在我国南方地区多分布在村落附近的斑块生境中,成熟后的种子直接落在母树下或被鸟类等动物搬运至其他斑块中。林下地面种子会被地面活动的动物搬运,继而影响种子命运及种群更新。于2016年、2017年南方红豆杉果期,在浙江天目山一个红豆杉种群分布地(临安市桐坑村),采用野外种子摆放实验的方法研究了动物对地面种子的搬运情况。结果表明:啮齿类动物取食是南方红豆杉地面种子消失的主要原因,但种子消失率在斑块间及边缘生境中的差异较大。母树林和竹林是啮齿类动物的主要觅食生境,两种生境的动物取食率明显高于山核桃种植园。边缘生境成为啮齿类斑块间移动的通道,而非觅食场所。4种啮齿类动物中,淡腹松鼠(Callosciurus pygerythrus)在母树林斑块以外的生境中出现频率最高,而其他地面搬运者回避利用山核桃种植园,仅在母树林和竹林斑块中搬运南方红豆杉地面种子。可见,斑块生境中动物改变了南方红豆杉地面种子的空间沉积格局,进而影响植物种群的更新。     

The bacterial diversity in an anaerobic ammonium-oxidizing (anammox) reactor community

An anaerobic ammonium-oxidation (anammox) reactor was operated for more than 500 days and the anammox activity of the biomass in the reactor reached 0.58 kg N_total/kg VSS d. The removal ratios of NO₂⁻-N to NH₄⁺-N in both reactor and activity tests were nearly 1.1. The bacterial diversity in the reactor was investigated by analysis of 16S rRNA gene clone libraries and quantitative real-time PCR (qPCR). The analysis showed that more than half of the clones in the library were affiliated to recognized filamentous bacteria. The previously recognized anammox bacterium (AnAOB) Candidatus Kuenenia stuttgartiensis was only detected by using a Planctomycetes-specific 16S rRNA gene primer set. However, at least two different types of AnAOB were detected by the primer set targeting the hydrazine-oxidizing enzyme gene (hzo). The aerobic ammonium-oxidizing bacteria (AAOB) Nitrosomonas europaea–eutropha group, which is widely detected in oxygen-limited environments, was also found in this reactor. The result of qPCR indicated that AnAOB comprised 16% of the community population while AAOB comprised less than 1% in the reactor.     

2-bromoethanesulfonate (BES) Enhances Sulfate-reducing Bacterial Population and Dichlorodiphenyltrichloroethane (DDT) Dechlorination in an Anaerobic Paddy Soil

2-bromoethanesulfonate (BES) is a structural analogue of 2-mercaptoethanesulfonic acid (coenzyme M) and often used to specifically inhibit methanogenesis. The role of BES and sulfate on the reductive dechlorination of dichlorodiphenyltrichloroethane (DDT) was compared in an anaerobic soil slurry reactor of sulfate-reducing system in this study. The population of soil sulfate-reducing bacteria (SRB) was markedly decreased under DDT condition compared to DDT-free reactor, while greatly increased by sulfate and slightly increased by BES. However, the dechlorination rate of DDT was the highest in the DDT+BES treatment, followed in order by DDT+Sulfate and the control condition. In the DDT+BES treatment, more than 60% of DDT-Cl was cleaved within 16 weeks, which was about 124% and 369% greater than that in the DDT+Sulfate treatment and under the control condition, respectively. The results suggested that the inhibition of methanogenesis by BES was another pathway to improve sulfate-reducing activity and the related dechlorination rate of DDT in waterlogged soils.     

Digestion of sand-laden manure slurry in an upflow anaerobic solids removal (UASR) digester

Studies on the performance of a laboratory scale upflow anaerobic solids removal (UASR) digester were carried out using sand-laden cow manure slurries having total solids (TS) concentration as 50 and 100 g/l. Hydraulic retention time (HRT) was maintained as 32.4 days, which resulted in the volatile solids (VS) loading rates of 1 and 1.64 g/l d. The UASR system was designed to remove sand from the manure slurry, while anaerobically digesting biodegradable solids inside a single reactor. To enhance the contact of microorganisms and substrate, the liquor from the top of the digester was recirculated through the bed of settled solids at its bottom. Volatile solids reduction through this process was observed to be 62% and 68% in the case of feed slurries having TS concentration as 50 and 100 g/l (referred in the text as 5% and 10% feed slurries), respectively. The methane production rates were observed to be 0.22 and 0.38 l/l d, while methane yield was 0.21 and 0.27 l CH₄/g VS loaded, for 5% and 10% feed slurries, respectively. This indicates that the increase in the VS loading had a positive impact on methane production rate and methane yield. It would be of interest to study the performance of a UASR digester at higher solids loadings and with longer solids retention times. Nonetheless, the presented study showed that sand-laden manure slurries can be successfully digested in a UASR digester producing methane energy equivalent to 4 kW h per m³ of digester volume per day.     

EPS and SMP dynamics at different heights of a submerged anaerobic membrane bioreactor (SAMBR)

Membrane bioreactors (MBR) technology for wastewater offers many advantages over conventional technologies such as high effluent quality, less footprint and others. The main disadvantage of membrane bioreactors (MBR) is related to membrane fouling, which is mainly caused by extracellular polymeric substance (EPS) and soluble microbial products (SMP). This research studied EPS and SMP dynamics at different heights of a submerged anaerobic membrane bioreactor (SAMBR). The SAMBR was operated under two organic loading rates (OLR) (0.79 and 1.56 kg/m³ d) and was fed with synthetic wastewater with glucose as the carbon source. The results showed percentages of chemical oxygen demand (COD) removal above 95% and the highest COD removal rates were observed at the bottom of the reactor (>83%) for both OLR. The EPS showed a stratification with highest quantities in the supernatant. For the SMP the highest concentration was in the bottom of SAMBR where utilization predominated associated products whereas in the SAMBR supernatant predominated biomass associated products. The OLR change led to a significant increase in SMP accumulation but not in EPS. These facts showed that EPS and SMP dynamic in the SAMBR seemed to be mainly influenced by biological activity, total suspended solids concentration and substrate composition.     

Anaerobic methanethiol degradation and methanogenic community analysis in an alkaline (pH 10) biological process for liquefied petroleum gas desulfurization

Anaerobic methanethiol (MT) degradation by mesophilic (30 degrees C) alkaliphilic (pH 10) communities was studied in a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor inoculated with a mixture of sediments from the Wadden Sea (The Netherlands), Soap Lake (Central Washington), and Russian soda lakes. MT degradation started after 32 days of incubation. During the first 252 days, complete degradation was achieved till a volumetric loading rate of 7.5 mmol MT/L/day, and sulfide, methane, and carbon dioxide were the main reaction products. Temporary inhibition of MT degradation occurred after MT peak loads and in the presence of dimethyl disulfide (DMDS), which is the autooxidation product of MT. From day 252 onwards, methanol was dosed to the reactor as co-substrate at a loading rate of 3-6 mmol/L/day to stimulate growth of methylotrophic methanogens. Methanol was completely degraded and also a complete MT degradation was achieved till a volumetric loading rate of 13 mmol MT/L/day (0.77 mmol MT/gVSS/day). However, from day 354 till the end of the experimental run (day 365), acetate was formed and MT was not completely degraded anymore, indicating that methanol-degrading homoacetogenic bacteria had partially outcompeted the methanogenic MT-degrading archea. The archeal community in the reactor sludge was analyzed by DGGE and sequencing of 16S rRNA genes. The methanogenic archea responsible for the degradation of MT in the reactor were related to Methanolobus oregonensis. A pure culture, named strain SODA, was obtained by serial dilutions in medium containing both trimethyl amine and dimethyl sulfide (DMS). Strain SODA degraded MT, DMS, trimethyl amine, and methanol. Flow sheet simulations revealed that for sufficient MT removal from liquefied petroleum gas, the extraction and biological degradation process should be operated above pH 9.     

On-field study of anaerobic digestion full-scale plants (Part II): new approaches in monitoring and evaluating process efficiency

Biogas plants need easy and practical tools for monitoring and evaluating their biological process efficiency. As soon as, in many cases, biomass supply present considerable costs, full-scale anaerobic digestion (AD) processes must approach, as much as possible, the potential biogas yield of the organic mixture fed to the biodigesters. In this paper, a new indicator is proposed (the bio-methane yield, BMY), for measuring the efficiency in full-scale AD processes, based on a balance between the biochemical methane potential (BMP) of the input biomass and the residual BMP of the output materials (digestate). For this purpose, a one-year survey was performed on three different full-scale biogas plants, in the Italian agro-industrial context, and the bio-chemical processes were fully described in order to calculate their efficiencies (BMY = 87-93%) and to validate the new indicator proposed, as useful and easily applicable tool for full-scale AD plants operators.     

Effect of plant cover on seed removal by rodents in the Monte Desert (Mendoza,Argentina)

Abstract In desert areas, predation risk is one of the highest costs of foraging and is a major influence on animal behaviour. Several strategies are used by foragers for surviving and reproducing in desert areas. The foraging strategies of the small mammals of South American deserts are still poorly known. In this study, we investigated the foraging strategies of rodents of the Monte Desert in response to distance from seed sources to sheltered sites (i.e. shrubs) during two different seasons (wet and dry). We evaluated the relative rates of removal of two species of seeds (millet and sunflower) by rodents at two sites by establishing 80 seed sources, 40 in unsheltered microhabitats and 40 in sheltered microhabitats. We recorded both the number of caches and seed consumption for each source. We found that plant cover affected the foraging activity of rodents of the sand dunes in the Monte Desert because both consumption and numbers of caches constructed from sheltered seed sources were higher than those from unsheltered ones. Consumption of sunflower was higher in the wet season than it was in the dry season, when millet consumption increased. Sunflower was the preferred seed both from sheltered or unsheltered sources. We discuss the possible causes of the different foraging strategies used by rodents of the Monte Desert.     

Anaerobic digestion of food waste in a hybrid anaerobic solid–liquid system with leachate recirculation in an acidogenic reactor

Recirculation of the leachate in the acidogenic reactor was proposed to enhance anaerobic digestion of food waste in the hybrid anaerobic solid–liquid (HASL) system. Recirculation of the leachate in the acidogenic reactor provided better conditions for extraction of organic matter from the treated food waste and buffering capacity to prevent excessive acidification in the acidogenic reactor. It ensured faster supply of nutrients in the methanogenic reactor in experiment. The highest dissolved COD and VFA concentrations in the leachate from the acidogenic reactor were reached for shorter time and were 16,670 mg/l and 9450 mg/l in control and 18,614 mg/l and 11,094 mg/l in experiment, respectively. Recycling of the leachate in the acidogenic reactor intensified anaerobic digestion of food waste and diminished time needed to produce the same quantity of methane by 40% in comparison with anaerobic digestion of food waste without recirculation.