Treatment of dye-rich wastewater by an immobilized thermophilic cyanobacterial strain: Phormidium sp.

The removal of Remazol Blue and Reactive Black B by the immobilized thermophilic cyanobacterial strain Phormidium sp. was investigated under thermophilic conditions in a batch system, in order to determine the optimal conditions required for the highest dye removal. In the experiments, performed at pH 8.5, with different initial dye concentrations between 9.1 mg l⁻¹ and 82.1 mg l⁻¹ and at 45 °C, calcium alginate immobilized Phormidium sp. showed high dye decolorization, with maximum uptake yields ranging from 50% to 88% at all dye concentrations tested. When the effects of high dye concentrations on dye removal were investigated, the highest uptake yield in the beads was 50.3% for 82.1 mg l⁻¹ Remazol Blue and 60.0% for 79.5 mg l⁻¹ Reactive Black B. The highest color removal was detected at 45 °C and 50 °C incubation temperatures for all dye concentrations. As the temperature decreased, the removal yield of immobilized Phormidium sp. also decreased. At about 75 mg l⁻¹ initial dye concentrations, the highest specific dye uptake measured was 41.29–41.17 mg g⁻¹ for Remazol Blue and 47.69–43.82 mg g⁻¹ for Reactive Black B at 45 °C and 50 °C incubation temperatures, respectively, after 8 days incubation.     

Relationship between microbial activity and microbial community structure in six full-scale anaerobic digesters

High activity levels and balanced anaerobic microbial communities are necessary to attain proper anaerobic digestion performance. Therefore, this work was focused on the kinetic performance and the microbial community structure of six full-scale anaerobic digesters and one lab-scale co-digester. Hydrolytic (0.6–3.5 g COD g^?1 VSS d^?1) and methanogenic (0.01–0.84 g COD g^?1 VSS d^?1) activities depended on the type of biomass, whereas no significant differences were observed among the acidogenic activities (1.5–2.2 g COD g^?1 VSS d^?1). In most cases, the higher the hydrolytic and the methanogenic activity, the higher the Bacteroidetes and Archaea percentages, respectively, in the biomasses. Hydrogenotrophic methanogenic activity was always higher than acetoclastic methanogenic activity, and the highest values were achieved in those biomasses with lower percentages of Methanosaeta. In sum, the combination of molecular tools with activity tests seems to be essential for a better characterization of anaerobic biomasses.     

Aerobic granulation in sequencing batch reactors with different reactor height/diameter ratios

Effects of reactor height/diameter ratios ranged from 24 to 4 corresponding to reactor settling velocities from 12 to 2 m h^?1 on aerobic granulation were investigated. It was found that granules appeared after 1-week operation and granule volume percentages exceeded 50% after 2–3 weeks in four reactors. In addition, similar granule fraction of 94–96% was found at steady state in all four reactors. Sludge volume index (SVI), average sludge size, biomass density and granule settling velocity at steady state were around 50 ml g^?1, 1800 μm, 53 g l^?1 and 40 m h^?1, respectively, in four reactors. Extracellular polymeric substances (EPS) and specific oxygen uptake rate (SOUR) were around 38 mg g^?1 VSS and 40 mg O₂ g^?1 VSS h^?1, respectively. Denaturing gradient gel electrophoresis (DGGE) fingerprint of sludge in four reactors showed the same microbial population shift during the start-up period and same microbial community structure during steady-state period. These results recommended strongly that reactor height/diameter ratio or reactor setting velocity in the used range in this study did not affect granule formation, physical characteristics, microbial community structure of granules and stable operation of granular sludge reactor. Reactor height/diameter ratio thus can be very flexible in the practice, which is important for the application of aerobic granule technology.     

Volatile fatty acids accumulation and rhamnolipid generation in situ from waste activated sludge fermentation stimulated by external rhamnolipid addition

The solubilization and acidification of waste activated sludge (WAS) were apparently enhanced by external rhamnolipid (RL) addition. The maximum solute carbohydrate concentrations increased linearly from 48 ± 5 mg COD L⁻¹ in the un-pretreated WAS (blank) to 566 ± 19 mg COD L⁻¹, and protein increased from 1050 ± 8 to 3493 ± 16 mg COD L⁻¹ at RL dosage of 0.10 g g⁻¹ TSS. The highest VFAs concentration peaked at 3840 mg COD L⁻¹ at RL dosage of 0.04 g g⁻¹ TSS, which was 4.24-fold higher than the blank test. RL was generated in situ during WAS fermentation when external RL was added. It was detected that RL concentration was increased from initial 880 ± 92 mg L⁻¹ to 1312 ± 7 mg L⁻¹ at the end of 96 h with RL dosage of 0.04 g g⁻¹ TSS, which was increased to 1.49-fold. Meanwhile, methane production was notably reduced to a quite low level of 2.0 mL CH₄ g⁻¹ VSS, showing effective inhibition of methanogens by RL (58.8 mL CH₄ g⁻¹ VSS in the blank). In addition, the activity of hydrolytic enzymes (protease and α-glucosidase) was enhanced accordingly. VFAs accumulation and RL generation in situ demonstrated that the additional RL substantially performed enhanced biological effects for waste activated sludge fermentation.     

Freeze tolerance and accumulation of cryoprotectants in the enchytraeid Enchytraeus albidus (Oligochaeta) from Greenland and Europe

The freeze tolerance and accumulation of cryoprotectants was investigated in three geographically different populations of the enchytraeid Enchytraeus albidus (Oligochaeta). E. albidus is widely distributed from the high Arctic to temperate Western Europe. Our results show that E. albidus is freeze tolerant, with freeze tolerance varying extensively between Greenlandic and European populations. Two populations from sub Arctic (Nuuk) and high Arctic Greenland (Zackenberg) survived freezing at −15 °C, whereas only 30% of a German population survived this temperature. When frozen, E. albidus responded by catabolising glycogen to glucose, which likely acted as a cryoprotectant. The average glucose concentrations were similar in the three populations when worms were frozen at −2 °C, approximately 50 μg glucose mg⁻¹ tissue dry weight (DW). At −14 °C the glucose concentrations increased to between 110 and 170 μg mg⁻¹ DW in worms from Greenland. The average glycogen content of worms from Zackenberg and Nuuk were about 300 μg mg⁻¹ DW, but only 230 μg mg⁻¹ DW in worms from Germany showing that not all glycogen was catabolised during the experiment. Nuclear magnetic resonance spectrometry (NMR) was used to screen for other putative cryoprotectants. Proline, glutamine and alanine were up regulated in frozen worms at −2 °C but only in relatively small concentrations suggesting that they were of little significance for freeze survival. The present study confirms earlier reports that freeze tolerant enchytraeids, like other freeze tolerant oligochaete earthworms, accumulate high concentrations of glucose as a primary cryoprotectant.     

Effect of sulfate and iron on physico-chemical characteristics of anaerobic granular sludge

This research investigated the effect of the substrate composition (no substrate, glucose, glucose + sulfate or glucose + sulfate + iron) on the physico-chemical characteristics of two different anaerobic granular sludges as a function of time. The sludges were fed batch wise (pH 7, 30 °C) at an organic loading rate of 1.2 g COD l⁻¹ d⁻¹ (0.04 g COD g VSS⁻¹ day⁻¹) for 30 days. The presence of sulfate (COD/sulfate ratio = 1) in the feed of glucose fed anaerobic sludges did not change the physico-chemical characteristics throughout the incubation. In contrast, the presence of iron in the feed (in addition to glucose and sulfate, COD/iron ratio = 1) reduced the protein and carbohydrate content in the SMP and EPS with about 50% after 30 days incubation compared to the other feeding conditions. The sludge grown on glucose + sulfate + iron contained much more iron (+300–500%) and sulfur (+200–350%) than the other incubated sludges both after 14 and 30 days. The higher mineral content (lower VSS content) and the decrease of the EPS content contributed to the disintegration of iron fed granules, as shown by their lower size particles. However, the iron fed sludge displayed a higher granule strength than the other incubated sludges. Although an appreciable variation in the granule strength was noticed between the sludges investigated, it was not possible to relate these differences to their inorganic composition, the chemical composition of the extracted polymers or to the physical characteristics investigated.     

Operation of an Anammox SBR in the presence of two broad-spectrum antibiotics

The feasibility of the anaerobic ammonium oxidation (Anammox) process to treat wastewaters containing antibiotics was studied in this work. Concentrations ranging from 100 to 1000 mg L^?1 for tetracycline hydrochloride and from 250 to 1000 mg L^?1 for chloramphenicol were tested in batch assays. A strong inhibitory effect was observed for both antibiotics.A concentration of 20 mg L^?1 of chloramphenicol was continuously added to an Anammox Sequential Batch Reactor (SBR) system, causing a decrease of the nitrogen removal efficiency of 25%. The Specific Anammox Activity (SAA) of the biomass also decreased from 0.25 to 0.05 g N (g VSS d)^?1. Similar effects were observed when 50 mg L^?1 of tetracycline hydrochloride were continuously fed. Both antibiotics did not cause any changes in the physical properties of the biomass. A previous degradation step could be necessary in order to treat wastewaters containing inhibitory concentrations of antibiotics by the Anammox process.     

Simultaneous decrease in ammonia and hydrogen sulfide inhibition during the thermophilic anaerobic digestion of protein-rich stillage by biogas recirculation and air supply at 60 °C

We had proposed a novel method to reduce ammonia inhibition during thermophilic anaerobic digestion via recirculation of water-washed biogas into the headspace (R1 system) or liquid phase (R2 system) of reactors. The feasibility of reducing the ratio of recirculated biogas to biogas produced (called the biogas recirculation ratio) was investigated in the present study. Thermophilic anaerobic digestion at 53 °C and 60 °C with a biogas recirculation ratio of 150 facilitated stable digestion performance and biogas production at a higher organic loading rate of 7 g/L/d in the R1 system, while the ammonia removal efficiency increased 1.23-fold when the temperature increased from 53 °C to 60 °C. At 60 °C, the biogas recirculation ratios in the R1 and R2 systems decreased to 50 and 10, and the ammonia absorption rates were 6.1 and 8.3 mmol/L/d, respectively, without decreasing the anaerobic digestion performance. The ammonia absorption rate of 8.3 mmol/L/d in the R2 system was higher than the rate of 7.8 mmol/L/d at the biogas recirculation ratio of 150 in the R1 system. The hydrogen sulfide content in the biogas was reduced to less than 50 ppm by supplying air at 3% of the amount of biogas produced into the reactor.     

Biofilm and granular systems to improve Anammox biomass retention

Appropriate biomass retention in reactors is a crucial factor for the accurate operation of the anaerobic ammonium oxidation (Anammox) process due to the slow growth rate of this bacterial population. In the present work two different approaches were studied and compared to improve Anammox biomass retention minimizing wash-out events: (1) formation of granular biomass using influents with high inorganic salts concentrations by production of saline precipitates acting as promoters for biomass aggregation (reactor SBR1); (2) use of zeolite particles as carrier material for Anammox biofilm formation (reactor SBR2). Both alternatives allowed the reduction of biomass wash-out in the effluent to values as low as 18 mg VSS L⁻¹ (SBR1) and 3 mg VSS L⁻¹ (SBR2). As a consequence the biomass concentration increased significantly inside each reactor. In the case of the SBR2 the specific Anammox activity (SAA) of the biomass was also enhanced increasing from 0.35 up to 0.5 g N (g VSS d)⁻¹. Both approaches allow the improvement of the biomass retention, the first option indicating the suitability of the Anammox process to treat wastewaters with high salt content. The second one with zeolite particles could be a good strategy to apply the Anammox process to low salinity wastewaters.     

Phosphorus removal in a closed recirculating aquaculture system using the cyanobacterium Synechocystis sp. PCC 6803 strain lacking the SphU regulator of the Pho regulon

Phosphorus (P) accumulation in a closed recirculating aquaculture system (RAS) was studied using a goldfish tank as a model. It was found that the accumulated P in this system was soluble inorganic phosphates (Pi) and the highest concentration was up to 8 mg P/L after 40 days of fish cultivation. Phosphorus in the water was increased linearly with the rate of 0.19 mg P/L/day. A mutant strain of the cyanobacterium Synechocystis sp. PCC 6803 (ΔSphU) that lacks the SphU regulator of the Pho regulon could decrease Pi in the wastewater of RAS to the concentration below the P detection limit of 0.01 mg P/L at the rate of 2.07 ± 0.33 mg P/h g DW. This was corroborated by the increase of cellular polyphosphate and P content in the ΔSphU strain as revealed by fluorescence microscopy. After the first cycle of P removal, the cyanobacterial cells were recovered from wastewater by cell flocculation using chitosan. The flocculated cells could be reused for efficient P removal for the next 3 cycles.     

Solids hydrolysis and accumulation in a hybrid anaerobic digester-constructed wetlands system

The properties and behaviour of solids retained in a pilot plant constituted of an up-flow anaerobic sludge blanket (UASB) reactor and two constructed wetlands (CWs) were monitored over a 3-year period. The UASB (25.5 m³) was fed with raw municipal wastewater at a flow rate of 61–112 m³ d^?1 and a volumetric loading rate (VLR) of 0.75–1.70 kg TCOD m^?3 d^?1. The CWs (75 m² each) were operated in series and received a fraction (17–20 m³ d^?1) of the UASB effluent. The applied surface loading rates (SLR) were in the range of 3800–8700 g TCOD m^?2 d^?1 (UASB) and 11–15 g BOD₅ m^?2 d^?1 (CWs). The overall system removed 95% TSS, 85% TCOD and 87% BOD₅ on average. For influent VSS, the UASB removed 72.1% and gave a hydrolysis of 63.5%, while the average surplus sludge generation was 8.7%. Over the 3-year period, TSS and VSS accumulated in the CWs at rates of 1.07 and 0.56 kg m^?2 year^?1, respectively. The aerobic biodegradability of the accumulated solids ranged from 23 to 92 mg O₂ g VSS^?1 d^?1 and increased downstream in the CWs. About 59% of the VSS that entered the CWs was removed by hydrolysis, while 24% accumulated on granular media. These low solids accumulation rates were especially remarkable considering the high COD and BOD₅ loading rates applied. The system lay-out appear to be promising in terms of preventing clogging.     

In vivo temperature limitations of photosynthesis in Phaseolus vulgaris L

The purpose of this study was to evaluate the temperature response of photosynthesis in two common bean genotypes differing in crop yield when grown under warm conditions. The cultivar Nobre is sensitive to high temperatures, whereas Diplomata shows better crop yield under high temperatures. Plants were grown in a greenhouse prior to transferring to a controlled environment cabinet for the temperature treatments. In a first experiment, 30 days-old plants were subjected to a short exposure (1 day) at temperatures that varied from 9 °C to 39 °C. Diplomata had lower net CO₂ assimilation rate (A) at 15 °C and 21 °C, but higher from 27 °C to 39 °C. Photosynthetic parameters calculated from modeling the response of A to the intercellular CO₂ concentration suggested that the different temperature responses of the two genotypes are caused by different rates of diffusion of CO₂ to the assimilation site, not by differences in biochemical limitations of photosynthesis. While stomatal conductance (g_s) did not differ between the genotypes, mesophyll conductance (g_m) was slightly greater for Nobre at 15 °C, but much higher in Diplomata from 21 °C to 39 °C. In a second experiment, no difference was observed in biomass accumulation between the two genotypes after growth for 24 days under a 35/20 °C (day/night) regime. Hence, the differences in photosynthesis did not cause variation in plant growth at the vegetative stage. The differential genotypic response of g_m to temperature suggests that g_m might be an important limitation to photosynthesis in Nobre, the common bean genotype sensitive to elevated temperature. However, more studies are needed employing other methods for g_m evaluation to validate these results.     

Synthesis of thermo-sensitive copolymer with affinity butyl ligand and its application in lipase purification

In this study, thermo-sensitive N-alkyl substituted polyacrylamide polymer P_NNB was synthesized by using N-hydroxymethyl acrylamide(NHAM), N-isopropyl acrylamide (NIPA) and butyl acrylate (BA) as monomers, and its low critical solution temperature (LCST) was controlled to be 28 °C. The recovery of the thermo-sensitive polymer was over 98%. Butanol as a hydrophobic ligand was covalently attached onto polymer P_NNB and butyl ligand density was 80 μmol g^?1 polymer. The affinity polymer was used for purification of lipase from crude material. Optimized condition was pH 7.0, 35 °C adsorption temperature, 120 min adsorption time and 0.5 mg ml^?1 initial concentration of lipase. The adsorption isotherm accords with a typical Langmuir isotherm. The maximum adsorption capacity (Q_m) of the affinity polymer for lipase was 24.8 mg g^?1polymer. The affinity copolymer could be recycled by temperature-inducing precipitation and there was only about 6% loss of adsorption capacity after five recyclings. Specific activity of lipase was improved from 14 IU mg^?1 to 506 IU mg^?1 protein, and its recovery achieved 82%. The affinity polymer is suitable for the purification of target proteins from the crude material with large volume and dilute solution.     

Does UV-B influence biomass growth in lichens deficient in sun-screening pigments?

This study aimed to assess biomass growth as a response variable in lichens during short-term laboratory experiments. To do this, we studied the influence of UV-B and temperature on lichen performance including the synthesis of solar radiation screening cortical compounds. The pioneer lichen Xanthoria aureola from exposed sea cliffs and the old forest lichen Lobaria pulmonaria were cultivated for 15 days in the laboratory in a factorial experiments with temperature (12 and 21 °C) and UV-B (0, 0.1, 0.3 and 1.0 W m^?2) as treatments. Prior to the experiment, the cortical pigment parietin was non-destructively extracted from X. aureola, whereas the sampled shade-adapted thalli of L. pulmonaria lacked cortical melanic compounds. Therefore both lichens were deficient in cortical sun-screening compounds when the UV-B exposure started. At 12 °C, the relative growth rate was 7.2 ± 0.6 and 3.0 ± 0.8 mg g^?1 day^?1 in L. pulmonaria and X. aureola, respectively, reduced to 1.8 ± 0.5 and ?2.6 ± 0.9 mg g^?1 day^?1, at 21 °C. These figures showed that lichen growth is a useful response variable in short-term laboratory experiments. Growth was not influenced by UV-B alone in these pigment-deficient transplants, suggesting that UV-B had little adverse effects on either of the lichen bionts. The cortical sun screens (parietin and melanic compounds) were synthesized in the presence of UV-B, and increased statistically significantly with increasing UV-B at both cultivation temperatures. However, in X. aureola the synthesis was highest at the lowest temperature (12 °C). At 12 °C, changes in chlorophylls, F_v/F_m and NPQ during cultivation were consistent with a substantial level of acclimation to the growth chamber conditions for both species, whereas strong reductions in photosynthetic pigments, F_v/F_m and Ф_II at 21 °C indicated serious damage and chlorophyll degradation at high temperature. In conclusion, lichen growth and the synthesis of protective compounds are highly responsive lichen processes in short-term experiments.     

Optimization of a biotransformation process to produce 4-(2,3,5,6-tetramethylpyrazine-1)-4′-demethylepipodophyllotoxin

The developed tandem biotransformation process for the directional biosynthesis of a designed compound 4-(2,3,5,6-tetramethylpyrazine-1)-4′-demethylepipodophyllotoxin (4-TMP-DMEP) by Alternaria alternata S-f6 was systematically optimized. 28 °C of culture temperature and 120 rpm of rotary shaker speed were suitable for the accumulation of 4-TMP-DMEP. The production (i.e., 11.1 ± 1.4 mg/L) of 4-TMP-DMEP was remarkably improved by using an initial yeast extract concentration of 2.5 g/L. 2.0 g/L of Span 80 was beneficial for the 4-TMP-DMEP production (i.e., 25.0 ± 1.5 mg/L). Furthermore, the 4-TMP-DMEP production was remarkably improved by one pulse feeding of 50 mg/L of DMEP on day 6 and two pulse feedings of 40 mg/L of TMP on days 8 and 14 when its residual level was below 50 mg/L and 10 mg/L, respectively. The 4-TMP-DMEP production of 45.1 ± 1.6 mg/L was obtained in the fed-batch biotransformation process, which was enhanced by 726% and 256%, comparing to that (i.e., 5.4 ± 0.4 mg/L and 0.9 mg/L/day) obtained in the batch biotransformation before optimization.     

Chemical compositions and characteristics of organic compounds in propolis from Yemen

Propolis is a gummy material made by honeybees for protecting their hives from bacteria and fungi. The main objective of this study is to determine the chemical compositions and concentrations of organic compounds in the extractable organic matter (EOM) of propolis samples collected from four different regions in Yemen. The propolis samples were extracted with a mixture of dichloromethane and methanol and analyzed by gas chromatography–mass spectrometry (GC–MS). The results showed that the total extract yields ranged from 34% to 67% (mean = 55.5 ± 12.4%). The major compounds were triterpenoids (254 ± 188 mg g⁻¹, mainly α-, β-amyryl and dammaradienyl acetates), n-alkenes (145 ± 89 mg g⁻¹), n-alkanes (65 ± 29 mg g⁻¹), n-alkanoic acids (40 ± 26 mg g⁻¹), long chain wax esters (38 ± 25 mg g⁻¹), n-alkanols (8 ± 3 mg g⁻¹) and methyl n-alkanoates (6 ± 4 mg g⁻¹). The variation in the propolis chemical compositions is apparently related to the different plant sources. The compounds of these propolis samples indicate that they are potential sources of natural bio-active compounds for biological and pharmacological applications.     

Dual purpose system that treats anaerobic effluents from pig waste and produce Neochloris oleoabundans as lipid rich biomass

Dual purpose systems that treat wastewater and produce lipid rich microalgae biomass have been indicated as an option with great potential for production of biodiesel at a competitive cost. The aim of the present work was to develop a dual purpose system for the treatment of the anaerobic effluents from pig waste utilizing Neochloris oleoabundans and to evaluate its growth, lipid content and lipid profile of the harvested biomass and the removal of nutrients from the media. Cultures of N. oleoabundans were established in 4 L flat plate photobioreactors using diluted effluents from two different types of anaerobic filters, one packed with ceramic material (D1) and another one packed with volcanic gravel (D2). Maximum biomass concentration in D1 was 0.63 g L⁻¹ which was significantly higher than the one found in D2 (0.55 g L⁻¹). Cultures were very efficient at nutrient removal: 98% for NNH₄⁺ and 98% for PO₄³⁻. Regarding total lipid content, diluted eflluents from D2 promoted a biomass containing 27.4% (dry weight) and D1 a biomass containing 22.4% (dry weight). Maximum lipid productivity was also higher in D2 compared to D1 (6.27 ± 0.62 mg L⁻¹ d⁻¹ vs. 5.12 ± 0.12 mg L⁻¹ d⁻¹). Concerning the FAMEs profile in diluted effluents, the most abundant one was C18:1, followed by C18:2 and C16:0. The profile in D2 contained less C18:3 (linolenic acid) than the one in D1 (4.37% vs. 5.55%). In conclusion, this is the first report demonstrating that cultures of N. oleoabundans treating anaerobic effluents from pig waste are very efficient at nutrient removal and a biomass rich in lipids can be recovered. The maximum total lipid content and the most convenient FAMEs profile were obtained using effluents from a digester packed with volcanic gravel.     

Partial nitrification under limited dissolved oxygen conditions

Partial nitrification to nitrite is technically feasible and economically favourable, especially when wastewaters contained high ammonium concentrations or low C/N ratios. Partial nitrification can be obtained by selectively inhibiting nitrite-oxidizing bacteria (NOB) through appropriate regulation of the pH, temperature and dissolved oxygen (DO) concentrations. The effect of pH, DO levels and temperature on ammonia oxidation rate and nitrite accumulation was investigated in order to determine the optimal conditions for partial nitrification of synthetic wastewater with high ammonia concentration. The experiments performed at low DO levels to lower the total oxygen needed in the nitrification step, which means great saving in aeration. During the start-up stage pH and DO were set at 7.0–7.4 and 0.5 mg/l, respectively. The reactor was operated until complete partial nitrification was achieved. The effect of pH, DO on partial nitrification was studied, as pH was kept at 6.5, 7.5, 8.5, 9.5 and DO at 0.5±0.2, 1.5±0.2 and 2.5±0.2 mg/l, and temperature at 30 °C. The influence of temperature on k_a value was studied by keeping pH=7.5, DO=1.5 mg/l and temperature was controlled at 12, 20 and 30 °C, respectively. The results showed that partial nitrification to nitrite was steadily obtained and the optimal operational parameters were pH=7.5, DO=1.5 mg/l, T=30 °C based on ammonia oxidation rate and nitrite accumulation rate. The maximum k_a was achieved and to be 115.1×10⁻³ mg NH₄⁺–N (mg VSS h)⁻¹ under this condition.     

Performance of an UASB reactor treating synthetic wastewater at low-temperature using cold-adapted seed slurry

The present study is an attempt to investigate if a long-term acclimation of digester contents to low-temperatures would improve wastewater treatment at low-temperatures similar to mesophilic ranges. The feasibility of low-temperature (15 °C) anaerobic treatment of synthetic wastewater in an upflow anaerobic sludge blanket reactor was studied using inoculum from a cattle manure digester adapted to 15 °C. The effect of varying hydraulic retention time was studied by decreasing the retention time from 7 days to 1 day. Under a constant temperature of 15 °C with a hydraulic retention time of 1 day and a corresponding loading rate of 7.2 g-chemical oxygen demand (COD)/l/day, 90–95% removal efficiency was achieved. The methane production of 250 l/kg-COD removed at standard temperature pressure (STP) is a major highlight of the study complementing the high treatment efficiency achieved. Loading rates >5 g-COD/l/day was accompanied by increase in effluent volatile fatty acids (VFA) concentrations. Due to the presence of a high concentration of active granular sludge in the lower compartment of the reactor, 80% reduction of COD occurred within the granular bed of the reactor. Treatment of low strength wastewater for a short period showed 70–75% removal efficiencies with methane yield of 300 l/kg-COD removed. Specific methanogenic activity profiles of the anaerobic biomass revealed low-temperature (15 °C) optima, indicating selection of cold-active microorganisms during the acclimation process. The SMA assays also indicate the development of a putatively psychrophilic acetoclastic methanogenic community and biogas analysis showed 75% efficiency in energy recovery as methane.     

Abundance and biomass of planktonic ciliates in the sea area around Zhangzi Island,Northern Yellow Sea

We investigated the abundance and biomass of planktonic ciliates in the sea area around Zhangzi Island, Northern Yellow Sea, from July 2009 to June 2010. Ciliates were sampled monthly from surface to bottom with a 10 m depth interval at 13 sample stations along three transects. A 1 L sample of water from each depth was collected with a 2.5 L Niskin water sampler and fixed in 1% acid Lugol’s iodine solution. Water samples were pre-concentrated using the Utermöhl method and observed using an Olympus IX51 inverted microscope at 100× or 200x. The dimensions of the ciliates were measured and the cell volume of each species was estimated using appropriate geometric shapes. The carbon:volume ratio used to calculate biomass was 0.19 pg C/μm³. Abundance and biomass of the ciliate in water column were calculated as the integral of the abundance and biomass from bottom to surface, respectively. The classification of tintinnids was based on taxonomic literature. The average abundance of non-loricate ciliates was 3066 ± 2805 ind/L, ranging from 165 ind/L (50 m depth of St. B6 in July) to 26,595 ind/L (surface of St. C1 in September). The average biomass of non-loricate ciliates was 2.88 ± 2.68 μg C/L, ranging from 0.05 μg C/L (10 m depth of St. A6 in July) to 20.51 μg C/L (surface of St. A5 in August). The average tintinnid abundance was 142 ± 273 ind/L, ranging from 0 ind/L (monthly) to 2756 ind/L (surface of St. A1 in July). The average tintinnid biomass was 0.84 ± 2.19 μg C/L, ranging from 0.00 μg C/L (every month) to 37.64 μg C/L (20 m depth of St. C5 in July). The results showed that the average abundance of total ciliates was 3208 ± 2828 ind/L, ranging from 166 ind/L (10 m depth of St. A6 in July) to 26,625 ind/L (surface of St. C1 in September); the average biomass of total ciliates was 3.73 ± 3.55 μg C/L, ranging from 0.05 μg C/L (10 m depth of St. A6 in July) to 38.29 μg C/L (20 m depth of St. C5 in July). Abundance and biomass were vertically homogeneous in February, November and December, but decreased dramatically from the surface down to the bottom in other months. 23 tintinnid species were identified, 12 of which were in genus Tintinnopsis. Tintinnid species were more abundant in February, July and August. Tintinnids occupied 6.6 ± 10.2% and 19.7 ± 23.3% of the total ciliate abundance and biomass, respectively, which increased during the warm season and at coastal stations, and decreased during the cold season and at offshore stations. Large non-loricate ciliate species were prevalent in spring, while smaller species dominated in summer and autumn. The average abundance of total ciliates in water column was 132 ± 72 × 10⁶ ind/m², with increases during spring and autumn. The average biomass of total ciliates in water column was 152.57 ± 93.10 mg C/m², with increases during spring and summer. The average abundance and biomass of total ciliates in water column were greater at offshore stations than at coastal stations during spring and autumn, and were lower during summer and winter. Non-loricate ciliates, tintinnids and total ciliates showed significant positive correlation with temperature and significant negative correlation with salinity (p < 0.01). Non-loricate ciliates and total ciliates showed significant positive correlation with Chl a concentration (p < 0.01); however, relationship between Chl a concentration and tintinnids was not significant.