Consumption Of Organic Matter Research Articles

Microbial processes and factors controlling their activities in alkaline lakes of the Mongolian plateau

A striking feature of the Mongolian plateau is the wide range of air temperatures during a year, -30 to 30°C. High summer temperatures, atmospheric weathering and the arid climate lead to formation of numerous alkaline soda lakes that are covered by ice during 6–7 months per year. During the study period, the lakes had pH values between 8.1 to 10.4 and salinity between 1.8 and 360 g/L. According to chemical composition, the lakes belong to sodium carbonate, sodium chloride-carbonate and sodium sulfate-carbonate types. This paper presents the data on the water chemical composition, results of the determination of the rates of microbial processes in microbial mats and sediments in the lakes studied, and the results of a Principal Component Analysis of environmental variables and microbial activity data. Temperature was the most important factor that influenced both chemical composition and microbial activity. pH and salinity are also important factors for the microbial processes. Dark CO2 fixation is impacted mostly by salinity and the chemical composition of the lake water. Total photosynthesis and sulfate-reduction are impacted mostly by pH. Photosynthesis is the dominant process of primary production, but the highest rate (386 mg C/(L∙d)) determined in the lakes studied were 2–3 times lower than in microbial mats of lakes located in tropical zones. This can be explained by the relatively short warm period that lasts only 3–4 months per year. The highest measured rate of dark CO2 assimilation (59.8 mg C/(L∙d)) was much lower than photosynthesis. The highest rate of sulfate reduction was 60 mg S/(L∙d), while that of methanogenesis was 75.6 μL СН4/(L∙d) in the alkaline lakes of Mongolian plateau. The rate of organic matter consumption during sulfate reduction was 3–4 orders of magnitude higher than that associated with methanogenesis.

Sand aggradation alters biofilm standing crop and metabolism in a low-gradient Lake Superior tributary

Sediment deposition changes the physical characteristics of river beds, and may alter the production and/or processing of allochthonous and autochthonous organic matter, with potential consequences for stream food webs. We conducted a comparative study of biofilm standing crop and metabolism in the Salmon Trout River, a tributary of Lake Superior where watershed disturbances have led to 3-fold increases in streambed fine sediments, predominately sand, in the past decade. We compared biofilm standing crop and metabolism rates using light–dark chambers in reaches where substrate consisted of predominately exposed rock or sand substrates. Biofilm chlorophyll a was 4.2-fold greater on rock substrates, but ash-free dry mass was 8-fold greater on sand substrates. Rates of gross primary production were 2 to 25-fold greater on rock versus sand substrates, and differences persisted whether rates were scaled for area or biofilm standing crop. In contrast, rates of respiration were similar on rock and sand substrates when scaled per unit area but 7–13 times lower on sand when scaled for biofilm standing crop. Together, these results suggest that sand aggradation in this river alters organic matter processing during the summer from net production to net consumption and storage of organic matter. Sand aggradation may alter the availability and processing of both allochthonous and autochthonous food resources in this forested river, with potential far-reaching impacts on the food web.

Effect of fermentation liquid from food waste as a carbon source for enhancing denitrification in wastewater treatment.

Food wastes were used for anaerobic fermentation to prepare carbon sources for enhancing nitrogen removal in wastewater treatment. Under anaerobic conditions without pH adjustment, the fermentation liquid from food wastes (FLFW) with a high organic acid content was produced at room temperature (25 °C) and initial solid concentration of 13%. Using FLFW as the sole carbon source of artificial wastewater for biological treatment by sequence batch operation, maximized denitrification (with a denitrification rate of V(DN) = 12.89 mg/gVSS h and a denitrification potential of P(DN) = 0.174 gN/gCOD) could be achieved at a COD/TN ratio of 6. The readily biodegradable fraction in the FLFW was evaluated as 58.35%. By comparing FLFW with glucose and sodium acetate, two commonly used chemical carbon sources, FLFW showed a denitrification result similar to sodium acetate but much better than glucose in terms of total nitrogen removal, V(DN), P(DN), organic matter consumption rate (V(COD)) and heterotrophy anoxic yield coefficient (Y(H)).

A stable isotopic study of the diet of <i>Potamonautes sidneyi</i> (Brachyura: Potamonautidae) in two coastal lakes of the iSimangaliso Wetland Park, South Africa

Potamonautes sidneyi Rathbun 1904, is a dominant freshwater crab in KwaZulu-Natal, South Africa. Recent flood events in the iSimangaliso Wetland Park have allowed a substantial range expansion of this species, including previously hypersaline and desiccated areas. A stable isotope study was conducted to examine the feeding habits of the populations from Lake Sibaya and Mpophomeni Stream, two contrasting sites in the iSimangaliso Wetland Park. Juveniles from Mpophomeni Stream were more depleted in δ 13 C and more enriched in δ 15 N compared to adults, indicating a more carnivorous diet and higher trophic position. A general shift in diet was observed at both sites, with consumption of aquatic invertebrates and sedimentary organic matter more prevalent in the wet summer months, while greater proportions of detritus and microphytobenthos were consumed in autumn/winter. No significant difference was observed between adults from the two sites despite the abiotic variations. The species appears to play a complex role in the trophic web, by acting as an intermediate consumer facilitating the flow of nutrients across levels and by breaking down decomposing organic matter, allowing for rapid recycling of nutrients within its ecosystem. Keywords : diet, trophic role, stable isotopes, freshwater, brachyurans, opportunistic feeders

Combining asymmetrical flow field-flow fractionation with on- and off-line fluorescence detection to examine biodegradation of riverine dissolved and particulate organic matter

This study demonstrated that asymmetrical flow field-flow fractionation (AF4) coupled with on-line UV and fluorescence detection (FLD) and off-line excitation-emission matrix (EEM) fluorescence spectroscopy can be employed to analyze the influence of microbial metabolic activity on the consumption and production of freshwater organic matter. With the AF4 system, organic matter is on-line enriched during a focusing/relaxation period, which is an essential process prior to separation. Size-fractionated chromophoric and fluorophoric organic materials were simultaneously monitored during the 30-min AF4 separation process. Two fractions of different sizes (dissolved organic matter (DOM) and particulate organic matter (POM)) of freshwater samples from three locations (up-, mid-, and downstream) along the Han River basin of Korea were incubated with the same inoculum for 14 days to analyze fraction-specific alterations in optical properties using AF4-UV-FLD. A comparison of AF4 fractograms obtained from pre- and post-incubation samples revealed that POM-derived DOM were more susceptible to microbial metabolic activity than was DOM. Preferential microbial consumption of protein-like DOM components concurred with enhanced peaks of chromophoric and humic-like fluorescent components, presumably formed as by-products of microbial processing. AF4-UV-FLD combined with off-line identification of microbially processed components using EEM fluorescence spectroscopy provides a powerful tool to study the relationship between microbial activity and composition as well as biodegradability of DOM and POM-derived DOM from different origins, especially for the analysis of chromophoric and fluorophoric organic matter that are consumed and produced by microbial metabolic activity. The proposed AF4 system can be applied to organic matter in freshwater samples having low concentration range (0.3–2.5ppm of total organic carbon) without a pre-concentration procedure.

Cold-water coral reefs and adjacent sponge grounds: hotspots of benthic respiration and organic carbon cycling in the deep sea

Cold-water coral reefs and adjacent sponge grounds are distributed widely in the deep ocean, where only a small fraction of the surface productivity reaches the seafloor as detritus. It remains elusive how these hotspots of biodiversity can thrive in such a food-limited environment, as data on energy flow and organic carbon utilization are critically lacking. Here we report in situ community respiration rates for cold-water coral and sponge ecosystems obtained by the non-invasive aquatic Eddy Correlation technique. Oxygen uptake rates over coral reefs and adjacent sponge grounds in the Traena Coral Field (Norway) were 9-20 times higher than those of the surrounding soft sediments. These high respiration rates indicate strong organic matter consumption, and hence suggest a local focusing onto these ecosystems of the downward flux of organic matter that is exported from the surface ocean. Overall, our results show that coral reefs and adjacent sponge grounds are hotspots of carbon processing in the food-limited deep ocean, and that these deep-sea ecosystems play a more prominent role in marine biogeochemical cycles than previously recognized.

Soil Penetration by Earthworms and Plant Roots--Mechanical Energetics of Bioturbation of Compacted Soils.

We quantify mechanical processes common to soil penetration by earthworms and growing plant roots, including the energetic requirements for soil plastic displacement. The basic mechanical model considers cavity expansion into a plastic wet soil involving wedging by root tips or earthworms via cone-like penetration followed by cavity expansion due to pressurized earthworm hydroskeleton or root radial growth. The mechanical stresses and resulting soil strains determine the mechanical energy required for bioturbation under different soil hydro-mechanical conditions for a realistic range of root/earthworm geometries. Modeling results suggest that higher soil water content and reduced clay content reduce the strain energy required for soil penetration. The critical earthworm or root pressure increases with increased diameter of root or earthworm, however, results are insensitive to the cone apex (shape of the tip). The invested mechanical energy per unit length increase with increasing earthworm and plant root diameters, whereas mechanical energy per unit of displaced soil volume decreases with larger diameters. The study provides a quantitative framework for estimating energy requirements for soil penetration work done by earthworms and plant roots, and delineates intrinsic and external mechanical limits for bioturbation processes. Estimated energy requirements for earthworm biopore networks are linked to consumption of soil organic matter and suggest that earthworm populations are likely to consume a significant fraction of ecosystem net primary production to sustain their subterranean activities.

Hydrogen production in a microbial electrolysis cell fed with a dark fermentation effluent

The organic matter consumption and hydrogen production rate were evaluated in a two-chamber microbial electrolysis cell (MEC). Three chemical oxygen demand (COD) concentration levels (400, 600 and 1200 mg/L) were tested. The COD was composed of a mixture of volatile fatty acids (VFAs) present in the effluent of a dark fermentation process. The two levels of voltage studied were 350 and 550 mV. The performance of the MEC was evaluated using either an anionic (AEM) or cationic exchange membrane (CEM). The robustness of the MEC was tested using two dark fermentation effluents, one with VFAs and another containing 1100 mg/L glucose. The highest production rates (81 mL/L/day) were obtained with 550 mV, and 85 % COD consumption was attained. No considerable differences in the hydrogen production rate were observed when the COD was increased from 400 to 1200 mg/L using 550 mV. However, maximal hydrogen production rates were obtained with the lower COD concentration using 350 mV. Neither the employment of AEM and CEM nor the change from synthetic substrate to real substrate resulted in remarkable changes in MEC performance. The substrate containing glucose was more slowly degraded because glucose was first transformed into VFAs, and then the VFAs were consumed to produce hydrogen. In this case, methane and carbon dioxide were detected.

Simultaneous pollutant removal and electricity generation in denitrifying microbial fuel cell with boric acid-borate buffer solution.

A double-chamber denitrifying microbial fuel cell (MFC), using boric acid-borate buffer solution as an alternative to phosphate buffer solution, was set up to investigate the influence of buffer solution concentration, temperature and external resistance on electricity generation and pollutant removal efficiency. The result revealed that the denitrifying MFC with boric acid-borate buffer solution was successfully started up in 51 days, with a stable cell voltage of 205.1 ± 1.96 mV at an external resistance of 50 Ω. Higher concentration of buffer solution favored nitrogen removal and electricity generation. The maximum power density of 8.27 W/m(3) net cathodic chamber was obtained at a buffer solution concentration of 100 mmol/L. An increase in temperature benefitted electricity generation and nitrogen removal. A suitable temperature for this denitrifying MFC was suggested to be 25 °C. Decreasing the external resistance favored nitrogen removal and organic matter consumption by exoelectrogens.

The role of lipids in activated sludge floc formation

Activated sludge is widely used to treat municipal and industrial wastewater globally and the formation of activated sludge flocculates (flocs) underpins the ability to separate sludge from treated water. Despite the importance of activated sludge flocs to human civilization there have been precious few attempts to rationally design fit for purpose flocs using a bottom-up approach based on a solid scientific foundation. Recently we have been developing experimental models for activated sludge floc formation based on the colonization and consumption of particulate organic matter (chitin and cellulose). In this study we lay the foundation for investigation of activated sludge floc formation based on biofilm formation around spheres of the lipid glycerol trioleate (GT) that form spontaneously when GT is introduced into activated sludge incubations. Sludge biomass was observed to associate tightly with the lipid spheres. An increase in extracellular lipase activity was associated with a decrease in size of the colonized lipid spheres over a 25 day incubation. Bacterial community composition shifted from predominantly Betaproteobacteria to Alphaproteobacteria in GT treated sludge. Four activated sludge bacteria were isolated from lipid spheres and two of them were shown to produce AHL like quorum sensing signal activity, suggesting quorum sensing may play a role in lipid spheres colonization and biodegradation in activated sludge. The development of this experimental model of activated sludge floc formation lays the foundation for rational production of flocs for wastewater treatment using lipids as floc nuclei and further development of the flocculate life-cycle concept.

Assessing the O2 budget under sea ice: An experimental and modelling approach

Abstract The objective of this study was to assess the O2 budget in the water under sea ice combining observations and modelling. Modelling was used to discriminate between physical processes, gas-specific transport (i.e., ice-atmosphere gas fluxes and gas bubble buoyancy) and bacterial respiration (BR) and to constrain bacterial growth efficiency (BGE). A module describing the changes of the under-ice water properties, due to brine rejection and temperature-dependent BR, was implemented in the one-dimensional halo-thermodynamic sea ice model LIM1D. Our results show that BR was the dominant biogeochemical driver of O2 concentration in the water under ice (in a system without primary producers), followed by gas specific transport. The model suggests that the actual contribution of BR and gas specific transport to the change in seawater O2 concentration was 37% during ice growth and 48% during melt. BGE in the water under sea ice, as retrieved from the simulated O2 budget, was found to be between 0.4 and 0.5, which is in line with published BGE values for cold marine waters. Given the importance of BR to seawater O2 in the present study, it can be assumed that bacteria contribute substantially to organic matter consumption and gas fluxes in ice-covered polar oceans. In addition, we propose a parameterization of polar marine bacterial respiration, based on the strong temperature dependence of bacterial respiration and the high growth efficiency observed here, for further biogeochemical ocean modelling applications, such as regional or large-scale Earth System models.

Impact of Exotic Earthworms on Organic Carbon Sorption on Mineral Surfaces and Soil Carbon Inventories in a Northern Hardwood Forest

Exotic earthworms are invading forests in North America where native earthworms have been absent since the last glaciation. These earthworms bioturbate soils and may enhance physical interactions between minerals and organic matter (OM), thus affecting mineral sorption of carbon (C) which may affect C cycling. We quantitatively show how OM-mineral sorption and soil C inventories respond to exotic earthworms along an earthworm invasion chronosequence in a sugar maple forest in northern Minnesota. We hypothesized that mineral surface area in A horizons would increase as burrowing earthworms incorporated clay minerals from the B horizons and that enhanced contacts between OM and minerals would increase the OM sorption on mineral surfaces and mineral-associated C inventories in A horizons. Contrary to our hypotheses, mineral surface areas within A horizons were lowered because earthworm burrows only extended into the silt-rich loess that separated the A and clay-rich B horizons. Furthermore, where endogeic earthworms were present, a smaller fraction of mineral surface area was covered with OM. OM sorption on minerals in the A horizons shifted from a limitation of mineral surface availability to a limitation of OM availability within a decade after the arrival of endogeic earthworms. C-mineral sorption depends on earthworm consumption of OM as well as the composition and vertical distribution of minerals. This finding may thus explain the contradictory results reported in earlier investigations. Our results highlight the rapid and drastic effects of exotic earthworms on key ecosystem processes in deciduous forests in post-glacial settings.

Quantifying fire‐wide carbon emissions in interior Alaska using field measurements and Landsat imagery

Carbon emissions from boreal forest fires are projected to increase with continued warming and constitute a potentially significant positive feedback to climate change. The highest consistent combustion levels are reported in interior Alaska and can be highly variable depending on the consumption of soil organic matter. Here we present an approach for quantifying emissions within a fire perimeter using remote sensing of fire severity. Combustion from belowground and aboveground pools was quantified at 22 sites (17 black spruce and five white spruce-aspen) within the 2010 Gilles Creek burn in interior Alaska, constrained by data from eight unburned sites. We applied allometric equations and estimates of consumption to calculate carbon losses from aboveground vegetation. The position of adventitious spruce roots within the soil column, together with estimated prefire bulk density and carbon concentrations, was used to quantify belowground combustion. The differenced Normalized Burn Ratio (dNBR) exhibited a clear but nonlinear relationship with combustion that differed by forest type. We used a multiple regression model based on transformed dNBR and deciduous fraction to scale carbon emissions to the fire perimeter, and a Monte Carlo framework to assess uncertainty. Because of low-severity and unburned patches, mean combustion across the fire perimeter (1.98 ± 0.34 kg C m−2) was considerably less than within a defined core burn area (2.67 ± 0.40 kg C m−2) and the mean at field sites (2.88 ± 0.23 kg C m−2). These areas constitute a significant fraction of burn perimeters in Alaska but are generally not accounted for in regional-scale estimates. Although total combustion in black spruce was slightly lower than in white spruce-aspen forests, black spruce covered most of the fire perimeter (62%) and contributed the majority (67 ± 16%) of total emissions. Increases in spring albedo were found to be a viable alternative to dNBR for modeling emissions.

An approach to mechanistic event recognition applied on monitoring organic matter depletion in SBRs

A fundamental practice in process engineering is monitoring the state dynamics of a system. Unfortunately, observability of some states is related to high costs, time, and efforts. The mechanistic event recognition (MER) aims to detect an event (defined as a change of the system with specific significance to the operation of the process) that cannot be directly observed but has some predictable effect on the dynamics of the systems. MER attempts to apply fault diagnosis techniques using mechanistic “recognition” models to describe the process. A systematic method for building recognition models using optimal experimental design tools is presented. As proof of concept, the MER approach to detect organic matter depletion in sequencing batch reactors, measuring only ammonia, dissolved oxygen, and nitroxides is applied. The event, that is, consumption of organic matter to a level below 50 gCOD/m3, was successfully detected even though microbial activity is known to continue after organic matter depletion. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3460–3472, 2014

Responses of young rams to level of hydrolised feather meal subtitution in ration

Feather meal contains more than 90% protein that most of this protein (70%) are ruminally undegradable, therefore it is a potential source of by pass protein. The study was done to evaluate the response of young rams to hydrolised feather meal (HBA) substitution in ration. Twenty five young rams aged 7-8 months, with average body weight of 21.16 ± 2.47 kg were used in this study. This study was conducted based on ramdomized block design and the rams were grouped into 5 groups based on body weight. The ration consisted of 30% grass and 70% feed supplement on dry matter basis. Feed supplement of the control diet (R0) contained 72% of total digestible nutrient (TDN) and 15% of total crude protein (CP), whereas R1-R4 were the improved rations that contained 75% of TDN and 18% of CP. HBA was used to substitute feed protein and as by pass protein source. The HBA substitution was done in 5 levels, namely: R0 = grass + feed supplement with 0% HBA; R1 = grass + feed supplement with 1.1% HBA; R2 = grass + feed supplement with 2.2% HBA; R3 = grass + feed supplement with 4.4% HBA and R4 = grass + feed supplement with 8.5% HBA. The study was conducted for 12 weeks. The results showed that the increase of CP in ration and HBA substitution did not affect dry matter (DM), organic matter (OM) consumption, as well as DM, OM and CP digestibility. The substitution of HBA in ration significantly increased CP consumption of ram fed R1, R2, R3 and R4 compared to R0 (143.86; 142.58; 147.46; 134.43 vs 109.98 g/head). The level of NH 3 -N in rumen fluid was significantly (P<0.01) affected by CP in the ration and HBA substitution. On the other hand total VFA and molar volatile fatty acids were not different except for molar isobutirat. The value of N retention and average daily gain (ADG) were affected (P<0.05) by level of CP and subtitution HBA in ration. The highest ADG value was resulted by rams received R2 diet (133.77 g/head). It was concluded that 2.2% HBA substitution in ration gave the best response on consumption, digestion, rumen fermentation, N retention and ADG. Key Words : Hydrolised Feather Meal, Substitution, Ram

Enhanced Input of Terrestrial Particulate Organic Matter Reduces the Resilience of the Clear-Water State of Shallow Lakes: A Model Study

The amount of terrestrial particulate organic matter (t-POM) entering lakes is predicted to increase as a result of climate change. This may especially alter the structure and functioning of ecosystems in small, shallow lakes which can rapidly shift from a clear-water, macrophyte-dominated into a turbid, phytoplankton-dominated state. We used the integrative ecosystem model PCLake to predict how rising t-POM inputs affect the resilience of the clear-water state. PCLake links a pelagic and benthic food chain with abiotic components by a number of direct and indirect effects. We focused on three pathways (zoobenthos, zooplankton, light availability) by which elevated t-POM inputs (with and without additional nutrients) may modify the critical nutrient loading thresholds at which a clear-water lake becomes turbid and vice versa. Our model results show that (1) increased zoobenthos biomass due to the enhanced food availability results in more benthivorous fish which reduce light availability due to bioturbation, (2) zooplankton biomass does not change, but suspended t-POM reduces the consumption of autochthonous particulate organic matter which increases the turbidity, and (3) the suspended t-POM reduces the light availability for submerged macrophytes. Therefore, light availability is the key process that is indirectly or directly changed by t-POM input. This strikingly resembles the deteriorating effect of terrestrial dissolved organic matter on the light climate of lakes. In all scenarios, the resilience of the clear-water state is reduced thus making the turbid state more likely at a given nutrient loading. Therefore, our study suggests that rising t-POM input can add to the effects of climate warming making reductions in nutrient loadings even more urgent.

Contrasting displacement of the sea cucumber Holothuria arguinensis between adjacent nearshore habitats

Many sea cucumber species are subjected to exponentially increasing fisheries worldwide; management of their populations should take into account their behavior. Yet, studies relating feeding rates and displacement of sea cucumbers are, to date, scarce. The abundance, particulate organic matter (POM) consumption and displacement of the sea cucumber Holothuria arguinensis were compared between two adjacent, vegetated, habitats: a macroalgal dominated bed and a seagrass meadow formed by Cymodocea nodosa, at the island of Gran Canaria (eastern Atlantic). Abundances of H. arguinensis did not differ between the macroalgal bed and the seagrass meadow. No differences were found neither in POM consumption nor POM content between habitats. Movement of H. arguinensis occurred continuously during the day and nighttime, i.e. without resting periods. No sheltering behavior was observed. Faster and longer displacements were detected on the seagrass meadow than in the macroalgal bed, probably as a result of the different topography between habitats, independently of the daily period (day vs. night) and the moon phase. As a result, differences in locomotion of H. arguinensis between the two habitats are not connected with differences in POM consumption rates between habitats. These results could be useful for managing current and future fisheries of this species in the Mediterranean Sea and the Atlantic Ocean.

The Use of Earthworm Eudrilus eugeniae in the Breakdown and Management of Poultry Waste

Abstract: Pot culture experiments were done to process poultry waste mixed with bedding materials (Eichhornia crassipes and cow dung) in the ratio of 1:1:2, 1:2:1 and 2:1:1 using earthworm Eudrilus eugeniae. Totally there were three treatments (T 1 , T 2 and T 3 ) with three replicates for each. The raw poultry waste, predigested poultry waste and vermicompost were separately subjected to chemical nutrients composition analysis. The vermicompost had increased levels of total N, P, K and Ca when compared to raw poultry waste and pre-digested poultry waste. The results of the present study suggest that the vermicomposted poultry waste with Eichhornia crassipes and cow dung at 2:1:1 proportion can very well be used as organic manure. Keywords: Earthworm, Poultry waste, Eichhornia crassipes , Vermicompost, Biomass. I. Introduction Poultry litter is usually applied as a fertilizer. Excessive land application of poultry litter can lead to surface water runoff of plant nutrients, which in turn can cause eutrophication of water reservoirs. Transportation of poultry litter out of the affected areas may decrease the negative environmental effects related to its land application; however, high transportation costs require adding value to poultry litter. Vermicomposting can potentially add value to poultry litter. Vermicomposting involves consumption and stabilization of organic matter by earthworms. Vermicomposting of poultry litter can not only produce value added fertilizer but it can also produce worms which could be sold as fish bait and a protein source. Although several studies have been conducted on vermicomposting, limited available data presents numerous challenges while vermicomposting poultry litter. High ammoniacal-nitrogen concentration, auto heating, and high bulk density are some of the major concerns that need to be addressed while vermicomposting poultry litter. Eichhornia is the free floating invasive aquatic macrophytes that are known to cause severe damage to the aquatic habitat. Literature revealed that the noxious weeds like Eichhornia are resisted to the all physical, chemical, biological as well as hybrid methods that have been applied to eradicate it [1]. Eichhornia is commonly found in India and it is a problematic weed in a number of districts. It has choked hundred of water bodies in India. Ecologically devastating properties of Eichhornia can be profitably used as compost after as conversion by vermicompost [2]. The vermicomposting process is a result of the combined action of the earthworms and microflora living in earthworm intestines and in the growth medium. Vermicompost improve the soil structure, increasing the water holding capacity and porosity which facilitate the root respiration and growth [3, 4].

Enhanced nitrogen removal from ammonium-rich wastewater containing high organic contents by coupling with novel high-rate ANAMMOX granules addition

The ANAMMOX process with sequential biocatalyst addition (SBA-ANAMMOX process) was developed in sequencing batch reactor (SBR) to enhance nitrogen removal from ammonium-rich wastewater containing glucose content up to 800mgCOD/L. The nitrogen removal performance of the SBR operated with 800mgCOD/L was significantly enhanced after sequential adding 0.5gVSS/d of high-rate ANAMMOX granules (HASGs). Kinetics analyses showed that the HASGs possessed high nitrite affinity and strong resistance to organic matter, both of which contributed to the enhancement of autotrophic nitrogen removal. Consequently, ANAMMOX became the dominant reaction to metabolize nitrite under organic conditions; denitrification was limited due to the lack of electron acceptors (nitrite and nitrate); while sulfate reduction emerged as an important process for consumption of organic matter in the SBA-ANAMMOX system. It is suggested that employing the SBA-ANAMMOX process for treatment of organic ammonium-rich wastewater, the simultaneous removal of nitrogenous compounds as well as organic matter was quite possible.

Identifying the microbial communities and operational conditions for optimized wastewater treatment in microbial fuel cells

Microbial fuel cells (MFCs) are devices that exploit microorganisms as “biocatalysts” to recover energy from organic matter in the form of electricity. MFCs have been explored as possible energy neutral wastewater treatment systems; however, fundamental knowledge is still required about how MFC-associated microbial communities are affected by different operational conditions and can be optimized for accelerated wastewater treatment rates. In this study, we explored how electricity-generating microbial biofilms were established at MFC anodes and responded to three different operational conditions during wastewater treatment: 1) MFC operation using a 750 Ω external resistor (0.3 mA current production); 2) set-potential (SP) operation with the anode electrode potentiostatically controlled to +100 mV vs SHE (4.0 mA current production); and 3) open circuit (OC) operation (zero current generation). For all reactors, primary clarifier effluent collected from a municipal wastewater plant was used as the sole carbon and microbial source. Batch operation demonstrated nearly complete organic matter consumption after a residence time of 8–12 days for the MFC condition, 4–6 days for the SP condition, and 15–20 days for the OC condition. These results indicate that higher current generation accelerates organic matter degradation during MFC wastewater treatment. The microbial community analysis was conducted for the three reactors using 16S rRNA gene sequencing. Although the inoculated wastewater was dominated by members of Epsilonproteobacteria, Gammaproteobacteria, and Bacteroidetes species, the electricity-generating biofilms in MFC and SP reactors were dominated by Deltaproteobacteria and Bacteroidetes. Within Deltaproteobacteria, phylotypes classified to family Desulfobulbaceae and Geobacteraceae increased significantly under the SP condition with higher current generation; however those phylotypes were not found in the OC reactor. These analyses suggest that species related to family Desulfobulbaceae and Geobacteraceae are correlated with the electricity generation in the biofilm and may be key players for optimizing wastewater treatment rates and energy recovery in applied MFC systems.