Nitrogen availability of anaerobic swine lagoon sludge: sludge source effects

Increased numbers of swine producers will be removing sludge from their anaerobic waste treatment lagoons in the next few years, due to sludge exceeding designed storage capacity. Information on availability of nitrogen (N) in the sludge is needed to improve application recommendations for crops. The objective of this study was to investigate possible effects of different companies and types of swine operations on the availability of N in sludge from their associated lagoons. A laboratory incubation study was conducted to quantify the availability of N (i.e. initial inorganic N plus the potentially mineralizable organic N) in the sludge. Nine sludge sources from lagoons of sow, nursery and finishing operations of three different swine companies were mixed with a loamy sand soil (200 mg total Kjeldahl N kg(-1) soil) and incubated at a water content of 0.19 g. water g(-1) dry soil and 25+/-2 degrees C for 12 weeks. Samples were taken at eight times over the 12-week period and analyzed for inorganic N (i.e. NH(4)-N and NO(3)-N) to determine mineralization of organic N in the sludge. Company and type of swine operation had no significant effects (P < 0.05) on the pattern of inorganic N accumulation over time. Thus, inorganic N accumulation from all sludge sources was fit to a first order equation [Nt = Ni + No (1-e(-kt)]. This relationship indicated that of the 200 mg of total sludge N added per kg soil, 23.5% was in the form of potentially mineralizable organic N (No) and 17.5% was in the form of inorganic N (Ni). The sum of these two pools (41%) represents an estimate of the proportion of total N in the applied sludge in plant available form after the 12 week incubation. While plant N availability coefficients were not measured in this study, the lack of significant company or type of swine operation effects on sludge N mineralization suggests that use of the same plant N availability coefficient for sludge from different types of lagoons is justifiable. The validity of this interpretation depends on the assumption that variation in other components of different sludge sources such as Cu and Zn does not differentially alter N uptake by the receiver crops.     

Bacterial and archaeal phylogenetic diversity associated with swine sludge from an anaerobic treatment lagoon

Over the last decades, the demand for pork products has increased significantly, along with concern about suitable waste management. Anaerobic-lagoon fermentation for swine-sludge stabilization is a good strategy, although little is known about the microbial communities in the lagoons. Here, we employed a cloning- and sequencing-based analysis of the 16S rRNA gene to characterize and quantify the prokaryotic community composition in a swine-waste-sludge anaerobic lagoon (SAL). DNA sequence analysis revealed that the SAL library harbored 15 bacterial phyla: Bacteroidetes, Cloroflexi, Proteobacteria, Firmicutes, Deinococcus-Thermus, Synergystetes, Gemmatimonadetes, Chlorobi, Fibrobacteres, Verrucomicrobia and candidates division OP5, OP8, WWE1, KSB1, WS6. The SAL library was generally dominated by carbohydrate-oxidizing bacteria. The archaeal sequences were related to the Crenarchaeota and Euryarchaeota phyla. Crenarchaeota predominated in the library, demonstrating that it is not restricted to high-temperature environments, being also responsible for ammonium oxidation in the anaerobic lagoon. Euryarchaeota sequences were associated with the hydrogenotrophic methanogens (Methanomicrobiales and Methanobacteriales). Quantitative PCR analysis revealed that the number of bacterial cells was at least three orders of magnitude higher than the number of archaeal cells in the SAL. The identified prokaryotic diversity was ecologically significant, particularly the archaeal community of hydrogenotrophic methanogens, which was responsible for methane production in the anaerobic lagoon. This study provided insight into the archaeal involvement in the overall oxidation of organic matter and the production of methane. Therefore, the treatment of swine waste in the sludge anaerobic lagoon could represent a potential inoculum for the start-up of municipal solid-waste digesters.     

Biodiversity of constructed wetlands for wastewater treatment

Constructed wetlands are often built for wastewater treatment to mitigate the adverse effects of organic pollution in streams and rivers caused by inputs of municipal wastewater. However, there has been little analysis of biodiversity and related factors influencing the ecosystem functioning of constructed wetlands. The purpose of this study was to evaluate the biodiversity of two free-water-surface integrated constructed wetlands in subtropical Taiwan by analyzing the water quality, habitat characteristics, and biotic communities of algae, macrophytes, birds, fish, and aquatic macroinvertebrates in the treatment cells. Our results indicated that the two integrated constructed wetlands (Hsin-Hai II and Daniaopi Constructed Wetlands) achieved good performance in reducing the concentrations of total nitrogen (TN) and total phosphorus (TP), and loadings of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) from municipal sewage. In total, 58 bird species, 7 fish species, and 34 aquatic macroinvertebrate taxa were recorded in the two wetlands. The results of stepwise multiple regressions showed that the richness, abundance, and diversity of birds increased with wetland area. Fish richness and abundance respectively increased with wetland area and dissolved oxygen, while the diversity decreased with increases in TP concentrations. The richness and density of aquatic macroinvertebrates increased with the cover of aquatic macrophytes, while the diversity increased with wetland area. Ordination analyses indicated that variations in the community structures of birds, fishes, and aquatic macroinvertebrates were respectively best explained by water temperature, wetland area, and species richness of fish. Our results suggest that wetland area, cover of aquatic macrophytes, and water quality were the most important factors governing the diversity in the constructed wetlands, and that the factors influencing community structures varied among different taxonomic groups. In addition to improving water quality, this study implied that the biodiversity of constructed wetlands for wastewater treatment can be enhanced through proper design and management.     

Denitrification of high nitrate wastewater in a cloth strip bioreactor with immobilized sludge

Denitrification of synthetic high nitrate wastewater containing 40,000?ppm NO₃ (9,032?ppm NO₃-N) was achieved using immobilized activated sludge in a column reactor. Active anoxic sludge adsorbed onto Terry cloth was used in the denitrification of high nitrate wastewater. The operational stability of the immobilized sludge system was studied both in a batch reactor and in a continuous reactor. The immobilized sludge showed complete degradation of different concentrations of NO₃-N (1,129, 1,693, 3,387, 6,774, and 9,032?ppm) in a batch process. The reactors were successfully run for 90?days without any loss in activity. The immobilized cell process has yielded promising results in attaining high denitrifying efficiency.     

Anaerobic ammonium oxidation in sediments of surface flow constructed wetlands treating swine wastewater

Applied Microbiology and Biotechnology - Anaerobic ammonium oxidation (anammox) was suggested to be involved in the nitrogen (N) removal process in constructed wetlands (CWs). Nevertheless, its...     

污水处理厂污泥膨胀和污泥发泡的比较分析

活性污泥法由于操作简单、处理效果好被广泛应用于市政污水和工业废水的处理。污泥膨胀和污泥发泡现象影响二次沉淀池的泥水分离过程和生物反应池的微生物量稳定,严重困扰着污水处理厂的正常运行,被称为污水处理厂的"癌症"。本文从污泥膨胀和污泥发泡的定义及分类出发,全面地比较了表征污泥膨胀和污泥发泡的方法、引起污泥膨胀和污泥发泡的丝状细菌种类及控制污泥膨胀和污泥发泡方法的异同,并探讨了污泥膨胀和污泥发泡问题的未来研究方向和控制策略,期望能够为今后污泥膨胀和污泥发泡问题的研究和调控提供有价值的参考。     

Hybrid constructed wetlands for wastewater treatment and reuse in the Canary Islands

The performance of two substrates commonly available in the zone, gravel and lapilli, was tested for their use in hybrid constructed wetland pilot plants for the treatment and reuse of urban wastewater in Gran Canaria, Canary Islands, Spain. The first stage of the systems was a vertical subsurface-flow constructed wetland and the second stage was a horizontal subsurface-flow constructed wetland. Parallel experiments were carried out with one system containing only crushed stone basaltic gravel as substrate and the other with only lapilli, a very porous volcanic sediment. The comparative effect of substrate type, hydraulic loading rate and planting was studied.Tracer studies indicated that the experimental TRHs were significantly lower than the theoretical ones, particularly for the vertical flow with gravel. Though the vertical flow with lapilli performed better than the one with gravel, the hybrids showed quite similar removals.Planting or varying the hydraulic loading rate introduced little differences between the vertical flows or the hybrids. Average removals for the gravel-based hybrid constructed wetland were 86% for BOD, 80% for COD, 88% for ammonia-N, 96% for SS and turbidity, 24% for phosphate-P, and 99.5% for faecal coliforms and 99.7% for faecal enterococci. Thus, it can be concluded that hybrid constructed wetlands proved to be robust configurations for wastewater treatment in the Canary Islands.     

Spatial and temporal changes in the microbial community in an anaerobic swine waste treatment lagoon

Microorganisms are central to both the beneficial (organic degradation, nutrient removal, biogas production) and detrimental (odor production, pathogen contamination) effects of swine waste storage systems. In this study, both quantitative (real-time polymerase chain reaction) and qualitative (denaturing gradient gel electrophoresis, cloning, sequence analysis) molecular analyses were used to track spatial and temporal changes in the microbial community of swine slurry from a 0.4 ha anaerobic lagoon. The lagoon, located in a region of western Kentucky which has a humid, subtropical environment, was sampled on a monthly basis (n = 10) over a period of one year at four different depths (top, 51 cm from the top, 152 cm from the top, and bottom >198 cm). The concentration and diversity of Bacteroides sp. was seasonal (up to 90% decrease between March and June). Hespellia sp. and other clostridial species, on the other hand, were endemic in the slurry (concentrations up to 1.0 × 10⁷ cells mL^?1 slurry) regardless of time of the year or lagoon depth. Results suggest that there were seasonal effects on the microbial community in the swine lagoon, while the effect of depth was not as pronounced. Seasonal changes in the microbial community in stored wastes may be (directly or indirectly) correlated with changes in malodor emissions from lagoons.     

Effects of plants and microorganisms in constructed wetlands for wastewater treatment

Constructed wetlands are a natural alternative to technical methods of wastewater treatment. However, our understanding of the complex processes caused by the plants, microorganisms, soil matrix and substances in the wastewater, and how they all interact with each other, is still rather incomplete. In this article, a closer look will be taken at the mechanisms of both plants in constructed wetlands and the microorganisms in the root zone which come into play when they remove contaminants from wastewater. The supply of oxygen plays a crucial role in the activity and type of metabolism performed by microorganisms in the root zone. Plants' involvement in the input of oxygen into the root zone, in the uptake of nutrients and in the direct degradation of pollutants as well as the role of microorganisms are all examined in more detail. The ways in which these processes act to treat wastewater are dealt with in the following order: Technological aspects; The effect of root growth on the soil matrix; Gas transport in helophytes and the release of oxygen into the rhizosphere; The uptake of inorganic compounds by plants; The uptake of organic pollutants by plants and their metabolism; The release of carbon compounds by plants; Factors affecting the elimination of pathogenic germs.     

Modeling of activated sludge wastewater treatment processes

The performance of an activated sludge wastewater treatment process consisting of an aeration tank and a secondary settler has been studied. A tanks-in-series model with backflow was used for mathematical modeling of the activated sludge wastewater treatment process. Non-linear algebraic equations obtained from the material balances of MLSS (mixed liquor suspended solids or activated sludge), BOD (biological oxygen demand) and DO (dissolved oxygen) for the aeration tank and the settler and from the behavior of the settler were solved simultaneously using the modified Newton-Raphson technique. The concentration profiles of MLSS, BOD and DO in the aeration tank were obtained. The simulation results were examined from the viewpoints of mixing in the aeration tank and flow in the secondary settling tank. The relationships between the overall performance of the activated sludge process and the operating and design parameters such as hydraulic residence time, influent BOD, recycle ratio and waste sludge ratio were obtained.     

Heavy metal fractionation and organic matter stabilization in sewage sludge treatment wetlands

The presence of heavy metals in sludge stabilized in a reed bed system may affect its use for agricultural purposes. However, the environmental impact of sludge depends on the availability and phytotoxicity of these heavy metals.The aim of this research was to determine the effectiveness of a reed bed (Phragmites australis) sludge treatment system in two urban wastewater treatment plants in Italy after a three-year period of operation: (i) by estimating the process of sludge stabilization, following conventional and nonconventional parameters related to the evolution of organic matter quality (water soluble carbon, dehydrogenase activity, pyrolytic fragments); (ii) by following the heavy metal bioavailability in the sludge through their fractionation. For heavy metal fractionation, the Community Bureau of Reference (BCR) was followed.The results showed that there was mineralization and stabilization of sludge over time, suggested by the decrease of about 35% in water soluble carbon and of about 60-80% of dehydrogenase activity. Moreover, significant values of benzene (17%), toluene (31%) and phenol (9%) were found at the end of experimentation in both treatment wetlands, highlighting the re-synthesis of humic-like matter.The results also showed that the content of heavy metals after 30 months was associated with the less mobile fractions of the sludge (more than 60% of total heavy metal content for almost metal), in particular, the fraction linked to the organic matter.     

Rehabilitation by constructed wetlands of available wastewater treatment plant in Sakhnin

In rural areas, insufficient wastewater treatment often causes serious environmental problems, especially for human health. Due to this problem, new wastewater treatment plants (WWTP) should be constructed or upgraded. When considering economic and maintenance factors, constructed wetlands (CWs) are more desirable processes. The available WWTP located in the Northern Israeli town of Sakhnin was redesigned and upgraded. To rehabilitate the WWTP, six new CWs having different operating conditions were constructed as a pilot project. The most appropriate place of construction of the CWs was thought to be at the end of the WWTP. From the beginning of the system, inlet and outlet pollution parameters such as chemical oxygen demand (COD), ammonia (NH₄-N⁺), total suspended solids (TSS), and phosphorus (PO₄-P³⁻) were monitored in the CWs from August 2005 to February 2006. As a result the most appropriate CWs were found having Phragmites as plant and volcanic tufa as media material. The maximum removal efficiencies were 71.8% on COD, 92.9% on TSS, 63.8% on ammonia for CW5 tank. Adversely, phosphorus removal was not so high in CW5. Phosphorus removal was negligible in the study.     

Activated sludge treatment of synthetic wastewater containing pentachlorophenol

Activated sludge treatment of a pentachlorophenol (PCP)-containing synthetic waste was examined. With a waste containing some sugars, and 40-120 mg/L PCP, laboratory activated sludge required about seven days for acclimation. However, the prior addition of a quasipure culture of PCP-metabolizing Arthrobacter resulted in immediate acclimation. Even with acclimated sludge, however, the system was upset for two days by a simple step change from 40 to 120 mg/L of PCP. The stability of the system to such a shock load was considerably improved when a chemostat culture of the PCP-metabolizing Arthrobacter was fed slowly into the mixed liquor. Kinetic models were developed to describe the dynamic response of the system in terms of growth parameters, hydraulic detention time, sludge age, and bleed-in rate from the chemostat.     

人工湿地污水处理技术问题及改进措施研究进展

人工湿地作为一种绿色生态、低成本的污水处理技术,其应用日渐广泛。随着应用和机理研究的深入,传统湿地在运行过程中也涌现出各种问题。本文总结了近几年来人工湿地污水处理所出现的堵塞、脱氮效率低、污染负荷小、受温度影响大等问题,综述了国内外学者针对这些问题采取的内部系统强化、工艺改进以及与其他工艺类型组合等措施,并对今后人工湿地技术的发展方向进行探讨。     

Performances of constructed wetlands for municipal wastewater treatment in rural mountainous area

A global performance evaluation of an experimental Horizontal SubSurface Flow Constructed Wetlands (HSSF) was made after 6 years of functioning. This wetland is situated in French prealpine mountain, at 720 m elevation. The HSSF process treatment consists in a three-stage system dimensioned for 350 People Equivalent. Different helophytes were planted such as Typha latifolia, Phragmites australis and Scirpus maritimus. The mean hydraulic residence time for sewage was closed to 4–5 days, but in summer the mean pollutant residence time increases to 6 days due to an important evapotranspiration. There is no clogging of the gravel matrix and the hydraulic conductivity was very good and stabilized. Removal pollutant efficiency was determinate at each stages. There was a high removal of total suspended solids (TSS) all year around with an average of 95.6% (±3.6). More than 80% of removal occurred in the first stage. Physical processes (decantation, filtration) associated with biological oxidation were the principal factors of this removal. For COD and BOD₅, removal efficiency in the first stage were close to 60% on average and more than 90% at the outlet of the wetland. These results are similar to those observed with SSFW in many cases. Influence of temperature seems very weak because there were no significant seasonal variations of the process efficiency. Minimum effluent quality standards (30 mg l^–1 TSS; 120 mg l^–1 COD; 40 mg l^–1 BOD₅) were always respected. In cold periods, nutrients uptake was reduced but remained up to 60% in average. Mean bacterial removal efficiency was about two order of magnitude (99%) but can reach up to five order of magnitude in summer. These cyclic variations follow a sinusoidal variation around an annual mean. Pollutants removals were correlated to their respective loadings and no limits has been observed except for nitrogen. These results confirm that SSFW, an ecotechnology, should be considered as an alternative to conventional treatment methods (activated sludge, fixed biofilm) for small communities even in mountainous area.     

Coagulant selection and sludge conditioning in a slaughterhouse wastewater treatment plant

Attempts were made in this study to examine the effectiveness of polymer addition to the aeration tank effluent prior to sludge flotation as practiced in a slaughterhouse wastewater treatment plant. The plant currently uses 10 mg/l of polymer prior to sludge flotation, but alternative, less-expensive, chemicals such as alum could be equally effective. Therefore, experiments were conducted using the Standard Jar test to determine the performance of both alum (Al2SO4.6H2O) and organic polymer. The dosages used for alum ranged between 0 and 1000 mg/l, whereas polymer dosages varied between 0 and 90 mg/l. The (optimal) removal efficiency for suspended solids in the mixed liquor was obtained at 400 mg/l for alum and 30 mg/l for polymer. It is evident that addition of alum or polymer results in significant removal of suspended solids reaching up to 99% for alum and 96% for polymer but alum produced a more compacted sludge. Removal of filterable COD was much lower in both cases since the chemicals used target the colloidal and suspended portion of the COD rather than the soluble (filterable) part of the COD.     

Microbial composition of the activated sludge of Moscow wastewater treatment plants

The contribution of the major technologically important microbial groups (ammonium- and nitrite-oxidizing, phosphate-accumulating, foam-inducing, and anammox bacteria, as well as planctomycetes and methanogenic archaea) was characterized for the aeration tanks of the Moscow wastewater treatment facilities. FISH investigation revealed that aerobic sludge were eubacterial communities; the metabolically active archaea contributed insignificantly. Stage II nitrifying microorganisms and planctomycetes were significant constituents of the bacterial component of activated sludges, with Nitrobacter spp. being the dominant nitrifiers. No metabolically active anammox bacteria were revealed in the sludge from aeration tanks. The sludge from the aeration tanks using different wastewater treatment technologies were found to have differing characteristics. Abundance of the nitrifying and phosphate-accumulating bacteria in the sludge generally correlated with microbial activity in microcosms and with efficiency of nitrogen and phosphorus removal from wastewater. The highest microbial numbers and activity were found in the sludge of the tanks operating according to the technologies developed in the universities of Hannover and Cape Town. The activated sludge from the Novokur’yanovo facilities, where abundant growth of filamentous bacteria resulted in foam formation, exhibited the lowest activity. The group of foaming bacteria included Gordonia spp. and Acinetobacter spp utilizing petroleum and motor oils, Sphaerotilus spp. utilizing unsaturated fatty acids, and Candidatus ‘Microthrix parvicella’. Thus, the data on abundance and composition of metabolically active microorganisms obtained by FISH may be used for the technological control of wastewater treatment.     

The effect of stratification and seasonal variability on the profile of an anaerobic swine waste treatment lagoon

In this study, the characterization of an anaerobic swine waste treatment lagoon from a farrowing operation (approximately 2000 sows) was carried out to examine the dynamics of the system due to stratification and seasonal variability. Swine waste samples were taken at different depths with a pulley system equipped with a special sampler that allows for sampling exclusively at certain depth. Chemicals and microbial dynamics were monitored throughout a one-year-period. Results showed that nutrient (C, N, P, S) concentrations varied according to stratified lagoon layers and season. Trace minerals (Al, Ca, Fe, and Mg), on the other hand, appeared to be affected more by stratification than seasonal variability. Molecular analysis also showed that microbial community structure appeared to be affected by the stratification and seasonal variability. Based on these data, it is important to consider the effect of stratification and seasonal variability in managing these open lagoons.     

Diversity and dynamics of Archaea in an activated sludge wastewater treatment plant

ABSTRACT: BACKGROUND: The activated sludge process is one of the most widely used methods for treatment of wastewater and the microbial community composition in the sludge is important for the process operation. While the bacterial communities have been characterized in various activated sludge systems little is known about archaeal communities in activated sludge. The diversity and dynamics of the Archaea community in a full-scale activated sludge wastewater treatment plant were investigated by fluorescence in situ hybridization, terminal restriction fragment length polymorphism analysis and cloning and sequencing of 16S rRNA genes. RESULTS: The Archaea community was specialized and dominated by Methanosaeta-like species. During a 15 month period major changes in the community composition were only observed twice despite seasonal variations in environmental and operating conditions. Water temperature appeared to be the process parameter that affected the community composition the most. Several terminal restriction fragments also showed strong correlations with sludge properties and effluent water properties. The Archaea were estimated to make up 1.6-% of total cell numbers in the activated sludge and were present both as single cells and colonies of varying sizes. CONCLUSIONS: The results presented here show that Archaea can constitute a constant and integral part of the activated sludge and that it can therefore be useful to include Archaea in future studies of microbial communities in activated sludge.