Energy analysis for onsite and offsite suburban wastewater

The environmental consequence of meeting the planet’s energy requirements has shown that biological degradation of organic constituent from wastewater does not only produces biogas. It also produces flammable methane that has 21 times more global warming potential or greenhouse effect than carbon dioxide. This becomes a loss of potential renewable energy when it is flared. This study investigates recoverable energy from cassava wastewater and effect of unrecovered onsite (not from treatment plant) wastewater energy. Sludge from both onsite untreated and offsite treated wastewater from a cassava processing station in a sub urban community of Nigeria was analyzed. The result shows that the offsite treatment has a methane potential of 27.428 m³/day compared to the onsite methane emission potential with 17.807 m³/day. The onsite 17.807 m³/day of methane is equivalent to 0.126 kgCH₄/year of emitted methane base on industrial procedure standards by the IPCC (2006) guidelines for national greenhouse gas inventories. An additional 54.03% of methane will be recovered if the onsite emissions were to be captured . At an emission efficiency of 0.025 kgCH₄/kg COD, the untreated wastewater indicates a potential contribution to the greenhouse effect. A mathematical model analysis was presented for ease in determining the amount of methane emitted from the untreated wastewater. This study support suggested methodologies and previous work comparing anaerobic offsite methane potential and untreated wastewater methane emission potentials along with its greenhouse effects.     

Experimental investigation of energy properties for Stigonematales sp. microalgae as potential biofuel feedstock

Microalgae has been considered potential biofuel source from the last decade owing to its versatile perspectives such as excellent capability of CO₂ capture and sequestration, water treatment, prolific growth rate and enormous energy content. Thus, energy research on microalgae is being harnessed to mitigate CO₂ and meet future energy demands. This study investigated the bioenergy potential of native blue-green microalgae consortium as initial energy research on microalgae in Brunei Darussalam. The local species of microalgae were assembled from rainwater drains, the species were identified as Stigonematales sp. and physical properties were characterised. Sundried biomass with moisture content ranging from 6.5% to 7.37% was measured to be used to determine the net and gross calorific value and they were 7.98 MJ/kg-8.57 MJ/kg and 8.70 MJ/kg-9.45 MJ/kg, respectively. Besides that, the hydrogen content, ash content, volatile matter, and bulk density were also experimented and they were 2.56%-3.15%, 43.6%-36.71%, 57–38%-63.29% and 661.2 kg/m³-673.07 kg/m³, respectively. Apart from experimental values, other physical bioenergy parameters were simulated and they were biomass characteristic index 61,822.29 kg/m³-62,341.3 kg/m³, energy density 5.27 GJ/m³-5.76G J/m³ and fuel value index 86.19–88.54. With these experimental results, microalgae manifested itself a potential source of biofuel feedstock for heat and electricity generation, a key tool to bring down the escalated atmospheric greenhouse gases and an alternation for fossil fuel.     

Current status of urban wastewater treatment plants in China

The study reported and analyzed the current state of wastewater treatment plants (WWTPs) in urban China from the perspective of treatment technologies, pollutant removals, operating load and effluent discharge standards. By the end of 2013, 3508 WWTPs have been built in 31 provinces and cities in China with a total treatment capacity of 1.48 × 10⁸ m³/d. The uneven population distribution between China's east and west regions has resulted in notably different economic development outcomes. The technologies mostly used in WWTPs are AAO and oxidation ditch, which account for over 50% of the existing WWTPs. According to statistics, the efficiencies of COD and NH₃–N removal are good in 656 WWTPs in 70 cities. The overall average COD removal is over 88% with few regional differences. The average removal efficiency of NH₃–N is up to 80%. Large differences exist between the operating loads applied in different WWTPs. The average operating loading rate is approximately 83%, and 52% of WWTPs operate at loadings of < 80%, treating up to 40% of the wastewater generated. The implementation of discharge standards has been low. Approximately 28% of WWTPs that achieved the Grade I-A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918–2002) were constructed after 2010. The sludge treatment and recycling rates are only 25%, and approximately 15% of wastewater is inefficiently treated. Approximately 60% of WWTPs have capacities of 1 × 10⁴ m³/d–5 × 10⁴ m³/d. Relatively high energy consumption is required for small-scale processing, and the utilization rate of recycled wastewater is low. The challenges of WWTPs are discussed with the aim of developing rational criteria and appropriate technologies for water recycling. Suggestions regarding potential technical and administrative measures are provided.     

Effect of sample conditioning and chamber loading on rate of formaldehyde release from wood products in a desiccator test

Several variables may influence the observed rate of formaldehyde (CH₂O) offgassing from wood products in a small static test chamber. We studied the effect of sample conditioning at ≈100% relative humidity and chamber loading (sample size) on CH₂O release rate from particle board (PB) and plywood (PW). Samples of PB and PW were placed in glass desiccators with reservoirs of water at a loading of 21 m²/m³ (sample surface area per chamber volume). The rate of CH₂O offgassing from the PB did not change over several weeks under these conditions (0.24 μg/cm²/day), but the overall release rate from the PW decreased after 8 days. In another experiment, the loading of the desiccator had a major effect on the rate of CH₂O offgassing from PB over a loading range of 1 to 42 m²/m³. The same phenomenon was observed with different loadings of PW. The inverse of the observed release rate varied linearly with the chamber loading of PB or PW. At a loading which may be encountered in a house (0.25 m²/m³), the release rate coefficient for PB calculated from the above inverse relation was 22-fold higher than that measured at a more conventional test load of 21 m²/m³. These results indicate that great care should be exercised when using desiccator tests for assessing and comparing the potential strength of materials as sources of CH₂O in the indoor environment.     

Carbon fluxes from coarse woody debris in southern taiga forests of the Valdai Upland

Studies in three typical forest biotopes of the Valdai Upland were performed to evaluate the stocks and surface area of coarse woody debris from spruce and birch (in linear transects), its colonization by xylotrophic fungi (during reconnaissance surveys), and CO₂ emission (by a chamber method). The stock and surface area were minimum in a paludal birch forest (46.4 m³/ha and 960 m²/ha) and maximum in a decay area of spruce forest (256.1 m³/ha and 3761 m²/ha, respectively). The assemblages of wood-decay fungi had a composition typically found in southern taiga forests. The total CO₂ flux varied from 145 kg C-CO₂/ha per year in the paludal birch forest to 462 kg C-CO₂/ha per year in small herb–green moss spruce forest. It is concluded that air temperature is an informative predictor of seasonal C-CO₂ flux rate from coarse woody debris.     

Properties of alkali-activated fly ash: high performance to lightweight

Alkali ash material (AAM) concrete is a unique material that is sustainable and cost-effective because it utilises waste fly ash, and has properties superior to other concrete products. The AAM concrete described here is produced from the addition of inexpensive chemicals to fly ash. AAM can be used to create a wide range of materials including high performance concrete (HPC-AAM) and lightweight (LW-AAM). The high performance AAM provides rapid strength gain along with high ultimate strengths of more than 110 MPa (16000 psi). LW-AAM can produce materials with densities ranging from 1200 to 2200 kg/m³ and compressive strengths from 2 (290 psi) to 65 MPa (9500 psi). Both HPC-AAM and LW-AAM have far better environmental resistance than Portland cement concrete, resisting attack from sulphuric acid (H₂SO₄), hydrochloric acid (HCl) and organic acids. AAMs resists freeze–thaw attack and high abrasion, possesses low chloride permeability and does not exhibit alkali silica reactivity.     

Hydrodynamics of the Segara Anakan lagoon

A hydrodynamic field study of the Segara Anakan lagoon combined with a reconstruction of the recorded data using a three-dimensional numerical model provides insights into the processes driving the hydrodynamics of the lagoon. This includes bathymetry, quantification of water volume fluxes with ADCP measurements, sea level recordings, salinity measurements, water budget and numerical model results for the periods of the field studies. Salinity measurements at the Klaces village show a complete flushing of the western lagoon during neap tide in the rainy season, which is assumed to increase the sedimentation. Mean salinities of the western part are in the order of 10 and 21 g/kg, while the eastern part has a larger mean salinity of 27 and 32 g/kg for the rainy and dry season, respectively. A numerical sensitivity study shows a relationship between the Citanduy discharge and the nett water volume transport between the eastern and western part of Segara Anakan. A nett transport to the west, which differs from neap to spring tides, turns to zero when Citanduy discharges are between 300 and 400 m³/s. The flushing time of the lagoon depends on the monsoon season and is about 1–3 days at the western outlet and increases to 12 days in the central parts.     

Atmospheric releases from fossil fuel power plants in the United States

This paper contains detailed data on atmospheric emissions from power plants with a capacity of more than 25 MW electric in the United States. The data are gathered from utility files as presented to the U.S. Environmental Protection Agency. Pollutants covered are CO, NO_x, SO_x3, particulates, and total hydrocarbons. The data indicate that in 1977 about 420×10⁹ kg coal, 84×10⁶ m³ oil, and 65×10⁶ m³ of natural gas were used to generate electricity. Pollutants generated were 2×10⁹kg particulates, 17×10⁹ kg SO₂, 6×10⁹ kg NO_x, 78×10⁶ kg hydrocarbons and 0.3×10⁶ kg of CO.     

Effect of cigarette smoking on residential NO2 levels

Two studies evaluating the levels and sources of nitrogen dioxide in approximately 90 employee homes in the Richmond area with continuous sampling during the weeks of August 5, 1980, and February 9, 1981, were performed using samplers in the living room, bedroom, kitchen, and outdoors. Additional data were collected concerning appliance usage, heating/cooling plant, ventilation and cigarette smoking. Results were analyzed using BMDP routines. The largest contributor to NO₂ concentration was found to be gas-fired kitchen appliances. The mean kitchen level for homes with gas appliances during the winter study was 188 μg/m³. Excluding participants with gas kitchens, incremental influence due to cigarette smoking was detected. The 7-day, 3-room average level of NO₂ in the homes of nonsmokers and smokers without gas-fired appliances was 12 and 15 μg/m³, respectively, in the summer. The corresponding winter values were 19 and 22 μg/m³. Furthermore, the individual levels of NO₂ in the homes of smokers were generally below both the adjacent outdoor level and the National Ambient Air Quality Standard limit for annual exposure.     

A method to derive the relationship between the annual and short-term air quality limits—Analysis using the WHO Air Quality Guidelines for health protection

The World Health Organization (WHO) Air Quality Guidelines (AQG) were launched in 2006, but gaps remain in evidence on health impacts and relationships between short-term and annual AQG needed for health protection. We tested whether relationships between WHO short-term and annual AQG for particulates (PM₁₀ and PM_2.5) and nitrogen dioxide (NO₂) are concordant worldwide and derived the annual limits for sulfur dioxide (SO₂) and ozone (O₃) based on the short-term AQG. We obtained air pollutant data over seven years (2004–2010) in seven cities from Asia-Pacific, North America and Europe. Based on probability distribution concept using maximum as the short-term limit and arithmetic mean as the annual limit, we developed a new method to derive limit value one from another in each paired limits for each pollutant with capability to account for allowable exceedances. We averaged the limit derived each year for each city, then used meta-analysis to pool the limit values in all cities. Pooled mean short-term limit for NO₂ (140.5 μg/m³ [130.6–150.4]) was significantly lower than the WHO AQG of 200 μg/m³ while for PM₁₀ (46.4 μg/m³ [95CI:42.1–50.7]) and PM_2.5 (28.6 μg/m³ [24.5–32.6]) were not significantly different from the WHO AQG of 50 and 25 μg/m³ respectively. Pooled mean annual limits for SO₂ and O₃ were 4.6 μg/m³ [3.7–5.5] and 27.0 μg/m³ [21.7–32.2] respectively. Results were robust in various sensitivity analyses. The distribution relationships between the current WHO short-term and annual AQG are supported by empirical data from seven cities for PM₁₀ and PM_2.5, but not for NO₂. The short-term AQG for NO₂ should be lowered for concordance with the selected annual AQG for health protection.     

Spatio-temporal variation of macrobenthic communities in the mangrove-fringed Segara Anakan lagoon, Indonesia, affected by anthropogenic activities

The benthic macrofauna of the Segara Anakan lagoon, Java, Indonesia and its fringing mangroves were investigated between May 2004 and August 2006. This lagoon has been affected by various human activities for decades, in particular fishing, effluents from agriculture and industry, and illegal deforestation. In total, 163 taxa were identified, including 127 species occurring in the mangrove forest and 59 species in the subtidal. Mean density of macrobenthos was 2.5-fold higher in the central (881.8 ± 1,151.3 ind. m^?2) than in the eastern mangrove site (356.3 ± 218.8 ind. m^?2). Community structures differed significantly between these sites and showed a serial shift during the investigation period. Gastropods dominated the community in the central mangrove location, whereas sipunculids, polychaetes and gastropods had similar densities in the eastern site. Differences in community composition were best explained by three sediment properties: pore water salinity, δ¹³C_org, and C_org/N. It is suggested that small-scale heterogeneity of food availability and quality is a main factor determining the small-scale variability of the community composition. Compared to other Indo-West Pacific mangroves, species richness and densities are high. However, the dominance of specific taxa, especially of opportunistic species and the comparably low species richness in the subtidal of the lagoon may be attributed to the high sediment input by rivers in the central part and to the large-scale cutting of mangroves. Continuous tree logging will probably lead to a further spread of two fast growing understorey plants and thus to an increase of uniform swamp sites and a decrease of micro-habitats for benthic macrofauna. To our knowledge, this is the first detailed study on the spatio-temporal variation of benthic macrofauna in mangroves of Indonesia.     

The optimization of wastewater treatment via combined techniques: Part I: Combined biological — chemical treatment

The optimization of sewage treatment by the combination of high rate biological treatment with chemical coagulation to remove both organic and inorganic pollutants with special reference to phosphorus has been investigated. In an attempt to study the minimum biological treatment which will not adversely affect the efficiency of the combined system, three different organic loads, namely, 9.48, 20.0 and 27.85 BOD₅.m^?2d^?1, were examined. The coagulants used were ferric chloride and alum. Calcium oxide was used as a coagulant aid with ferric chloride. The results obtained showed that the efficiency of the combined system was found to be slightly affected by the organic load. The combined treatment technique used in this investigation proved to be very promising in removing both inorganic and organic pollutants.     

Indoor air pollution and inter-room pollutant transport due to unvented kerosene-fired space heaters

Two kerosene-fired space heaters, one white-flame convective and one blue-flame radiant, were operated in the master bedroom and living room of an unoccupied house (elevation: 1800 m) under several simulated use conditions. Tests were conducted in the master bedroom with the bedroom door and bedroom window open and closed. The heaters were operated until an 8 °C temperature rise was achieved in the room. Increases in bedroom concentrations of CO, CO₂, NO, NO₂, and O₂ are reported. The increases in CO₂ levels ranged from 2440 to 5440 mL/m³ (ppm) while the increases in NO₂ levels ranged from 0.12 to 0.60 mL/m³ (ppm). The NO₂ emission rate from the convective heater was reduced at the high altitude location as compared with previous emission rate measurements conducted near sea level with the same heater. In addition, inter-room pollutant transport rates are reported for bedroom tests conducted with the window closed. While inter-room pollutant transport rates were less than 10 m³ with the bedroom door closed (opening area less than 100 cm²), they ranged from 16 m³/h to 53 m³/h with the bedroom door open 2.5 cm (opening = 520 cm²), and ranged from 190 to 3400 m³/h with the door fully open (opening area = 15,000 cm²). Continuous emission rate data are reported for tests conducted with the heater in the living room.     

Oxidative potential and chemical composition of PM2.5 in office buildings across Europe – The OFFICAIR study

In the frame of the OFFICAIR project, indoor and outdoor PM_2.5 samples were collected in office buildings across Europe in two sampling campaigns (summer and winter). The ability of the particles to deplete physiologically relevant antioxidants (ascorbic acid (AA), reduced glutathione (GSH)) in a synthetic respiratory tract lining fluid, i.e., oxidative potential (OP), was assessed. Furthermore, the link between particulate OP and the concentration of the PM constituents was investigated.The mean indoor PM_2.5 mass concentration values were substantially lower than the related outdoor values with a mean indoor/outdoor PM_2.5 mass concentration ratio of 0.62 and 0.61 for the summer and winter campaigns respectively. The OP of PM_2.5 varied markedly across Europe with the highest outdoor OP^AA m⁻³ and OP^GSH m⁻³ (% antioxidant depletion/m³ air) values obtained for Hungary, while PM_2.5 collected in Finland exhibited the lowest values. Seasonal variation could be observed for both indoor and outdoor OP^AA m⁻³ and OP^GSH m⁻³ with higher mean values during winter. The indoor/outdoor OP^AA m⁻³ and OP^GSH m⁻³ ratios were less than one with 4 and 17 exceptions out of the 40 cases respectively. These results indicate that indoor air is generally less oxidatively challenging than outdoors. Correlation analysis revealed that trace elements play an important role in determining OP, in particular, the Cu content. Indoor air chemistry might affect OP since weaker correlations were obtained for indoor PM_2.5. Our findings also suggest that office workers may be exposed to health relevant PM constituents to a different extent within the same building.     

Odor-annoyance estimates from roadtraffic combustion exhausts: Calibration with master scaling using pyridine as a reference

The present field study addressed the need for a procedure that provides a defined unit of measurement of perceived annoyance from environmental odors, calibrating the estimates for individual scaling behavior and context effects. In including 25 subjects, the purpose was to demonstrate the applicability of the master-scale procedure with magnitude estimation to perform such a calibration of odor-annoyance estimates for target stimuli such as road-traffic combustion exhausts (13 000 vehicles/d; averaging 47 μg/m³ over the day/night with peaks exceeding 100 μg/m³ of nitrogen dioxide; NO₂). For comparison, calibrated estimates were also obtained for a backyard expected to be considerably less polluted (comparable with 18 μg/m³ of NO₂) and for blank stimuli presented indoors. The data transformation for the calibration procedure with which annoyance is expressed in either master-scale units or pyridine equivalents requires estimates of a reference stimulus for which seven concentrations of pyridine were used. The results provide an illustration of master scaling of odor annoyance, and imply that use of a modulus (standard stimulus with a predefined annoyance magnitude), in contrast to master scaling, is not sufficient for calibration for individual scaling behavior and context effects.     

Investigation of equilibria involving carbon dioxide, carbonates and water

Several laboratory techniques are reviewed in this paper, which yield reliable data on carbonate equilibria. In particular, it is emphasized that pco₂ variation is necessary in order to potentiometrically distinguish between hydrogen carbonato and caronato complexes. The essential features of reliable solubility measurements of carbonate phases are summarized. A neglected autoclave technque is described which has been successfully applied for the synthesis of pure, crystalline, MnCO₃, FeCO₃ and CoCO₃. Details of a continuously operating solubility cell for experiments at 5–95°C are also given.Solubilty constants for different ionic media are related by the respective equilibrium vapor pressure of H₂O and the standard potentials of the respective metal electrodes. It is shown that a thermodynamic cycle can be exploited for an indirect determination of the Fe²⁺/Fe standard potential. The application of solubility data is discussed using the pco₂ control in the recent geologic past an an example.     

Association between long-term exposure to air pollution and mortality in France: A 25-year follow-up study

IntroductionLong-term exposure to air pollution (AP) has been shown to have an impact on mortality in numerous countries, but since 2005 no data exists for France.ObjectivesWe analyzed the association between long-term exposure to air pollution and mortality at the individual level in a large French cohort followed from 1989 to 2013.MethodsThe study sample consisted of 20,327 adults working at the French national electricity and gas company EDF-GDF. Annual exposure to PM₁₀, PM_10–2.5, PM_2.5, NO₂, O₃, SO₂, and benzene was assessed for the place of residence of participants using a chemistry-transport model and taking residential history into account. Hazard ratios were estimated using a Cox proportional-hazards regression model, adjusted for selected individual and contextual risk factors. Hazard ratios were computed for an interquartile range (IQR) increase in air pollutant concentrations.ResultsThe cohort recorded 1967 non-accidental deaths. Long-term exposures to baseline PM_2.5, PM_10-25, NO₂ and benzene were associated with an increase in non-accidental mortality (Hazard Ratio, HR = 1.09; 95% CI: 0.99, 1.20 per 5.9 μg/m³, PM_10-25; HR = 1.09;95% CI: 1.04, 1.15 per 2.2 μg/m³, NO₂: HR = 1.14; 95% CI: 0.99, 1.31 per 19.3 μg/m³ and benzene: HR = 1.10; 95% CI: 1.00, 1.22 per 1.7 μg/m³).The strongest association was found for PM₁₀: HR = 1.14; 95% CI: 1.05, 1.25 per 7.8 μg/m³. PM₁₀, PM_10-25 and SO₂ were associated with non-accidental mortality when using time varying exposure. No significant associations were observed between air pollution and cardiovascular and respiratory mortality.ConclusionLong-term exposure to fine particles, nitrogen dioxide, sulfur dioxide and benzene is associated with an increased risk of non-accidental mortality in France. Our results strengthen existing evidence that outdoor air pollution is a significant environmental risk factor for mortality. Due to the limited sample size and the nature of our study (occupational), further investigations are needed in France with a larger representative population sample.     

Inhibition of microbial activity of activated sludge by ammonia in leachate

Leachate samples were collected from the West New Territory Landfill (WENT), Hong Kong, and characterized in the laboratory. The analytical results confirmed that it has a typical nature of aged leachate with a low BOD₅/COD ratio of 0.22 and a high strength of ammonia-nitrogen around 5 g/L. A lab-scale study was conducted to investigate the inhibition of microbial activity of the activated sludge. In the first test, glucose-based synthetic wastewater was used in two parallel reactors. The experimental results demonstrated that COD removal declined from 95.1 to 79.1% and the dehydrogenase activity of the sludge decreased from 11.04 to 4.22 μg TF/mg mixed liquor suspended solids (MLSS), when the ammonia-nitrogen concentration increased from 50 mg/L to 800 mg/L progressively. The remaining NH₃⁺-N residue in the treated wastewater increased from 0.58 mg/L to 649 mg/L extensively. In the second test, mixed wastewater samples containing glucose and raw leachate were fed into six parallel biological reactors and operated on batch mode. The experimental results showed COD removal decreased from 97.7 to 78.1% and the dehydrogenase activity decreased from 9.29 to 4.93 μg triphenyl formazon (TF)/mg MLSS, respectively, when the ammonia-nitrogen concentration increased within the same range. Microbial inhibition could also be substantiated by a decrease of specific oxygen uptake rate (SOUR) from 68 to 45 mg O₂/g MLSS. These results suggested leachate containing high-strength ammonia-nitrogen should be pretreated to an acceptable NH₄⁺-N level before it is fed into biological reactors.     

Inorganic iodine incorporation into soil organic matter: evidence from iodine K-edge X-ray absorption near-edge structure

The transformation of inorganic iodine (I⁻ and IO₃⁻) incubated in soils with varying amounts of organic matter (Andosols from the surface layer of an upland field and forest, as well as Acrisols from surface and subsurface layers of an upland field) was investigated by using the iodine K-edge X-ray absorption near-edge structure (XANES). After 60 d of reaction, both I⁻ and IO₃⁻ were transformed into organoiodine in surface soils containing sufficient amounts of organic matter, whereas IO₃⁻ remained unchanged in the subsurface soil of Acrisols with low organic matter contents. Transformation of IO₃⁻ into organoiodine was not retarded when the microbial activity in soil was reduced by γ-ray irradiation, suggesting that microbial activity was not essential for the transformation of inorganic iodine into organoiodine. Soil organic matter has the ability to transform inorganic iodine into organoiodine.     

Pulmonary function changes in Chinese hamsters exposed six months to diesel exhaust

Chinese hamsters were exposed for eight hours per day to automotive diesel exhaust emissions which were diluted with air (18 to 1) and had a particulate level of 6.4 mg/m³. Pulmonary function measurements were made after six months exposure. Body weight (BW), lung weight (LW), vital capacity (VC), residual volume by water displacement (RV_w) and by gas dilution (RV_D), alveolar volume (V_A), and carbon monoxide transfer factor (D_LCO) were measured. LW showed a significant increase in the diesel exposed animals (P < 0.01) while VC, RV_W, and D_LCO showed decreases (P < 0.01). Static deflation volume-pressure curves showed depressed deflation volumes for diesel exposed animals when volumes were corrected for body weight and even greater depressed volumes when volumes were corrected for lung weight. However, when volumes were expressed as percent vital capacity, the diesel exposed animals had higher lung volumes at 0 and 5 cm H₂O. Results of the pathological examination of the lung tissue will be necessary for final analysis of our findings. However, preliminary interpretation indicates possible emphysematous changes which are compatible with the observed decrease in D_LCO.