Characteristics of biotic and abiotic removals of dissolved organic carbon in wastewater effluents using soil batch reactors.

Biodegradable dissolved organic carbon (BDOC) analyses and abiotic adsorption of dissolved organic carbon (DOC) from different wastewater effluent were conducted to evaluate biotic and abiotic removal mechanisms as a function of the initial DOC concentration and source of DOC using soil batch reactors. To obtain high DOC concentrations, a laboratory-scale reverse osmosis unit was used. It was found that BDOC fraction was independent of the initial DOC concentration and was dependent on the source of wastewater and/or the types of wastewater treatment. The BDOC fractions varied from 9 to 73%. Trickling filter effluent (Tucson, Arizona) showed the highest BDOC, ranging from 65 to 73% biodegradable, while wastewater treated by the soil aquifer treatment (SAT) (NW-4) was found to be most refractory, with DOC removals of 9 to 14%. For nitrified/denitrified tertiary effluent (Mesa, Arizona) and secondary effluent (Scottsdale, Arizona), 36 to 42% removal of DOC was observed during the BDOC test. The amount of BDOC in the wastewater depended not on the concentration of DOC, but on the effectiveness of pretreatment. Abiotic adsorption capacity of wastewater effluent varied from 6 to 18%. Molecular weight distribution analyses showed that more than 50% of DOC in the Scottsdale concentrate had a molecular weight of less than 1000 Da, and no significant change in distribution profiles occurred after approximately 12% abiotic adsorption with both soils with acclimated microorganisms (SAT soil) and soils without acclimated microorganisms (non-SAT soils). Hence, preferential adsorption was not observed and the presence of acclimated microbes did not influence adsorption.     

Parental care compromises feeding in the pumpkinseed (<Emphasis Type="Italic">Lepomis gibbosus</Emphasis>)

Providing parental care is potentially costly. Costs can arise through elevated energy expenditure or from an increased risk of mortality. A cost of parental care can also occur because a parent is compromised in their ability to forage. We used pumpkinseed Lepomis gibbosus, a fish with an alternative male mating strategy, to test whether parental males differed in their feeding in comparison with females and cuckolder males. To address this question, we examined the stomach contents of female, cuckolder male, and parental male pumpkinseed during the breeding season over an entire diel cycle. We showed that parental males had a lower total weight of food in their stomachs in comparison with females, while cuckolder males did not. Parental males also had a lower weight and number of chironomids in their stomachs. The temporal pattern of feeding of parental males diverged from that of females, and they had a lower probability of pupal chironomids in their stomachs, which implies spatial segregation in foraging. Parental males had a greater probability of conspecific eggs in their stomachs than females, while the probability of egg cannibalism did not differ between cuckolder males and females. Overall, these finding meet predictions in accordance with an assumption that parental care and territoriality can compromise feeding.     

Media surface properties and the development of nitrifying biofilms in mixed cultures for wastewater treatment

Plastic was tested to select biofilm support media that would enhance nitrification in the presence of heterotrophs. Eight different types (acrylonitrile butadiene styrene, nylon, polycarbonate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinyl chloride and tufnol) were immersed in an aerobic fed-batch reactor receiving domestic settled wastewater. Nitrification rates did not correlate with biomass concentrations, nor surface roughness of the plastics as measured by atomic force microscopy (AFM). The maximum nitrification rate of 1.5 g/m² d^?1 was obtained from biofilms growing on PTFE which had the lowest surface adhesion force (8 nN). Nitrification rates for the biofilms were inversely correlated with the attraction forces as measured by AFM.     

Nonylphenol in the environment: a critical review on occurrence, fate, toxicity and treatment in wastewaters

Nonylphenol is a toxic xenobiotic compound classified as an endocrine disrupter capable of interfering with the hormonal system of numerous organisms. It originates principally from the degradation of nonylphenol ethoxylates which are widely used as industrial surfactants. Nonylphenol ethoxylates reach sewage treatment works in substantial quantities where they biodegrade into several by-products including nonylphenol. Due to its physical-chemical characteristics, such as low solubility and high hydrophobicity, nonylphenol accumulates in environmental compartments that are characterised by high organic content, typically sewage sludge and river sediments, where it persists. The occurrence of nonylphenol in the environment is clearly correlated with anthropogenic activities such as wastewater treatment, landfilling and sewage sludge recycling. Nonylphenol is found often in matrices such as sewage sludge, effluents from sewage treatment works, river water and sediments, soil and groundwater. The impacts of nonylphenol in the environment include feminization of aquatic organisms, decrease in male fertility and the survival of juveniles at concentrations as low as 8.2 mug/l. Due to the harmful effects of the degradation products of nonylphenol ethoxylates in the environment, the use and production of such compounds have been banned in EU countries and strictly monitored in many other countries such as Canada and Japan. Although it has been shown that the concentration of nonylphenol in the environment is decreasing, it is still found at concentrations of 4.1 mug/l in river waters and 1 mg/kg in sediments. Nonylphenol has been referred to in the list of priority substances in the Water Frame Directive and in the 3rd draft Working Document on Sludge of the EU. Consequently there is currently a concern within some industries about the possibility of future regulations that may impose the removal of trace contaminants from contaminated effluents. The significance of upgrading sewage treatment works with advanced treatment technologies for removal of trace contaminants is discussed.     

Direct versus indirect methods of quantifying herbivore grazing impact on a coral reef

Two methods were used to assess the grazing impact of roving herbivorous fishes across a coral reef depth gradient within Pioneer Bay, Orpheus Island, Great Barrier Reef. The first technique employed was a method traditionally used to quantify herbivory on coral reefs via the (indirect) inference of herbivore impact from biomass estimates and reported feeding rates. The second method (one of a range of direct approaches) used remote underwater video cameras to film the daily feeding activity of roving herbivores in the absence of divers. Both techniques recorded similar patterns and relative levels of herbivore biomass across five reef zones at the study site. Indirect estimates of the grazing impact across the reef depth gradient of the three predominant species of herbivore broadly coincided with levels quantified directly by remote underwater video, indicating that, to a large extent, presence does correspond to function. However, the video data suggested that, for individual species in particular reef zones, the absolute level of impact may be less than that inferred from presence. In the case of the parrotfish Scarus rivulatus, the video recordings suggested that, at the reef crest, an average of 52% (±18 SE) of each m² area of reef would be grazed each month, compared with an area of 109% (±41 SE) suggested by inferring grazing activity from presence alone. Potential biases associated with remote video recorders may explain some of the discrepancy between values. Overall, the results suggest that, for some fish groups, the indirect method of inferring function from presence can provide a good indication of relative levels of herbivore impact across a coral reef. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Use of organic coagulant/flocculant for treatment of effluents generated in intensive rearing of swine

Separation of water for reuse is essential in an effluent treatment system, especially in activities with high water consumption, such as a pig production system. The objective of this work was to evaluate the efficiency of Tanfloc SG^® coagulant tannin/organic flocculant used to treat effluent generated during the intensive rearing of swine. For the evaluation, laboratory and in situ tests (field test) were performed. The laboratory tests were performed to define the concentration (1 and 16%), dosage (0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 milliliters of the solution), and time (24, 48, 72, and 96 hours) of coagulation/flocculation treatment of the solid portion of the effluent. The parameters pH, turbidity, oxidation reduction potential, dissolved oxygen, and electroconductivity (in microsiemens per centimeter) were evaluated using a multiparameter probe and the parameters ammonia (NH₃), nitrate (NO₃), and nitrite (NO₂) in the laboratory, in relation to the coagulation/flocculation time of the solid part of the effluent. The use of tannin as a coagulant/flocculant of plant origin in the treatment of swine effluents was effective in reducing turbidity and concentrations of ammonia, nitrite, and nitrate, and it allowed separation of the solid–liquid phase in approximately 68% as liquid phase.