SciCombinator

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Journal: Water science and technology : a journal of the International Association on Water Pollution Research

28

This paper analyses the Austrian water footprint of consumption (WF(cons)) for different diets: the current diet, a healthy diet (based upon the dietary recommendations issued by the German nutrition society, or DGE), a vegetarian diet and a combined diet between both latter diets. As in many western countries, the current Austrian diet consists of too many products from the groups sugar, crop oils, meat, animal fats, milk, milk products and eggs and not enough products from the groups cereals, rice, potatoes, vegetables and fruit. Especially the consumption of animal products accounts for high WF amounts. These diets result in a substantial reduction (range 922-1,362 l per capita per day (lcd)) of the WF(cons) for agricultural products, which is currently 3,655 lcd. However, the Austrian water footprint of agricultural production (WF(prod) = 2,066 lcd) still remains lower than even the WF(cons) for a vegetarian diet (2,293 lcd). As a result the country is a net virtual water importer regarding agricultural products for all analysed scenarios.

Concepts: Agriculture, Nutrition, Fat, Meat, Vegetarian cuisine, Diets, Vegetarianism, Veganism

27

This study aims to investigate solubilization of elements (P, N, K, Ca and Mg) during anaerobic digestion (AD) of solid agriculture waste. It is important to maintain particularly phosphorous in the aqueous phase to be able to subsequently recover it in a concentrated form via crystallization. Batch AD was carried out at a mesophilic condition (37 °C) and pH 7.0 ± 0.2 on a variety of piggery and poultry solid waste streams. Less than 10% of the total P, Ca and Mg was in soluble form in the digestate. Most of the N and K remained soluble in the digestate. A bioavailability test (citric acid extraction) showed P, Ca and Mg in the digestate were totally available. Complete solubilization of P, Ca and Mg occurred below a threshold of pH 5.5. This indicates these nutrients were released during digestion, and then either bound to form inorganic compounds or adsorbed on solid surfaces in the digestate. These effects reduce the feasibility of post-digestion recovery of the nutrients via struvite crystallization. Strategies to improve nutrient solubilization and recovery during the AD include addition of complexing chemicals, operation at depressed pH, or otherwise modifying the operating conditions.

Concepts: Acid, Nutrition, Nitrogen, Anaerobic digestion, Waste management, Citric acid, Mechanical biological treatment, Digestate

27

For this study, 34 water samples were collected along the Wei River and its tributaries. Multivariate statistical analyses were employed to interpret the environmental data and to identify the natural and anthropogenic trace metal inputs to the surface waters of the river. Our results revealed that Zn, Se, B, Ba, Fe, Mn, Mo, Ni and V were all detected in the Wei River. Compared to drinking water guidelines, the primary trace metal pollution components (B, Ni, Zn and Mn) exceeded drinking water standard levels by 47.1, 50.0, 44.1 and 26.5%, respectively. Inter-element relationships and landscape features of trace metals conducted by hierarchical cluster analysis (HCA) identified a uniform source of trace metals for all sampling sites, excluding one site that exhibited anomalous concentrations. Based on the patterns of relative loadings of individual metals calculated by principal component analysis (PCA), the primary trace metal sources were associated with natural/geogenic contributions, agro-chemical processes and discharge from local industrial sources. These results demonstrated the impact of human activities on metal concentrations in the Wei River.

Concepts: Cluster analysis, Iron, Water, Hydrogen, Multivariate statistics, Chemical element, Metal, Principal component analysis

27

An experimental study combining biological treatment with flocculation (F) and ultrafiltration (UF) membrane technology was conducted, separately and in combination, seeking to increase insight into the capability of such treatment processes to remove emerging contaminants (ECs). The occurrence and removal efficiencies of 17 ECs are reported for wastewater from Mexico City. Results showed that activated sludge (AS) is the predominant process for removing acidic pharmaceutical compounds, and the use of a cationic flocculant increases the biodegradability of these compounds as well as that of 4-nonylphenol. The UF process alone showed greater removal of phenolic compounds than AS. However, the contribution of flocculation to EC removal by the UF unit was fairly limited. In general, the F + AS + UF processes yielded better results than their separate use, leading to the highest removal rates of 15 of the 17 compounds. In the case of some phenolic compounds and the phthalic acid esters, a competitive sorption process between the membrane and the sludge steps seemed to take place. Bis-2-ethylhexylphthalate (DEHP) was found to be significantly sorbed onto sludge. The F + AS + UF process operated as a membrane bioreactor (MBR) using 16 gL(-1) of suspended solids in the mixed liquor (MLSS) yielded the highest removal efficiencies for the ECs tested.

Concepts: Alcohol, Water, Sewage treatment, Phenols, Industrial wastewater treatment, Activated sludge, Sewerage, Phthalic anhydride

23

Yeast activated sludge was developed and operated at salinities of 0, 15, 30, 45, and 60 g/l NaCl. The kinetics of the various sludges degrading a wastewater with glycerol as the carbon source were determined. Inhibition due to salinity was analyzed and it was found that the limiting concentration of NaCl is 120 g/l. Salinity affects the maximum growth rate of the sludge. Reactors were exposed to shock salinity changes. Salt shocks affected maximum growth rate of the reactors but treatment was still effective. The effect of pH adjustment was investigated and it was determined that hourly adjustments of pH led to the most effective treatment outcomes. Finally, DNA of the reactors was investigated. Although Scheffersomyces spartinae (Debaryomycetaceae family) was clearly more suited to the high salinity environment than other yeast species, even at high salinity the number of species was diverse. This suggests the potential to use a number of yeast species for high salinity wastewater treatment.

Concepts: Carbon dioxide, Effect, Affect, Sewage treatment, Seawater, Wastewater, Industrial wastewater treatment, Sewerage

22

Triclosan is a widely used antimicrobial agent and may pose health risks to many aquatic organisms. Photodegradation is an important transformation pathway for triclosan, but studies on the effects of inorganic anions on photodegradation of triclosan are limited. In the present study, the single and combined effects of NO3-, Cl- and HCO3- on the photolysis of triclosan in aqueous solutions under UV irradiation was evaluated. The results showed that photodegradation of triclosan was inhibited by NO3- and promoted by HCO3-, while no significant effect was observed with Cl-. When Cl- was added to NO3-, no effect was observed, but the addition of Cl- hindered the promotion effect of HCO3-. The coexistence of NO3-, Cl- and HCO3- inhibited the photolysis of triclosan. These results showed the complex effects of inorganic anions in the photolysis of triclosan and provide useful information for an accurate ecological risk assessment of triclosan in natural waters. It will also help to develop appropriate treatment ways of triclosan.

22

In this study a natural mix of microalgae grown in wastewater of municipal character was co-digested with sewage sludge in mesophilic conditions, in both batch and semi-continuous modes. The semi-continuous experiment was divided into two periods with OLR1 (organic loading rate) of 2.4 kg volatile solids (VS) m-3 d-1 and HRT1 (hydraulic retention time) of 15 days, and OLR2 of 3.5 kg VS m-3 d-1 and HRT2 of 10 days, respectively. Results showed stable conditions during both periods. The methane yield was reduced when adding microalgae (from 200 ± 25 NmL CH4 g VSin-1, to 168 ± 22 NmL CH4 g VSin-1) but VS reduction was also decreased by 51%. This low digestibility was confirmed in the anaerobic batch test. However, adding microalgae improved the dewaterability of the digested sludge. The high heavy metals content in the microalgae resulted in a high heavy metals content in the digestate, making it more difficult to reuse the digestate as fertilizer on arable land. The heavy metals are thought to originate from the flue gas used as a CO2 source during the microalgae cultivation. Therefore the implementation of CO2 mitigation via algal cultivation requires careful consideration regarding the source of the CO2-rich gas.

Concepts: Carbon dioxide, Carbon, Anaerobic digestion, Sewage, Wastewater, Natural gas, Heavy metal music, Sludge

0

Research on three-dimensional electrode system mainly focuses on the material of plate electrode and catalytic activity, and minimal attention is provided to particle electrode. Pyrolusite was prepared as a novel particle electrode with high active chlorine (ACl) yield. The particle electrode was characterised by scanning electrode microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and electrochemical properties. Results show that the intended pyrolusite particle electrode was prepared successfully. These pyrolusite particle electrodes were applied to degrade sulphonated phenolic resin in chlorine-containing wastewater and displayed an excellent catalytic activity. A total of 68.76 mg/L ACl was produced, and the CODCr removal rate was 49.55%. These results indicated that pyrolusite particle electrode is much more effective than the reference material, that is, granular activated carbon. Furthermore, the product of electrolytic process was characterised by gas chromatography-mass spectrometry (GC-MS) and ultraviolet visible spectrometry (UV-vis). The enhanced mechanism was proposed that the high degradation efficiency could be ascribed to the increase of ACl.

0

This study was conducted at a fish farm in Itacuruba, located in the Brazilian semiarid region. Its objective was to quantify the impacts of aquaculture on water quality by comparing effluent and inlet water, particularly in relation to CONAMA Resolution 430 (2011) limits. Regarding the effluent, electrical conductivity, total phosphorus (TP) and total nitrogen presented values above the limits, other parameters complied with the mentioned legislation. During the dry period, the effluent’s TP values were 447% higher than the inlet water and 473% above the Resolution limit. During the wet period, TP concentration in the inlet water increased 1,000% while the effluent exceeded legislation limits by 1,175%. Based on these results, treatment of effluent from fish farms in accordance with legislation prior to its release into the receiving water body is recommended, thereby minimizing eutrophication risk for the local population, guaranteeing food security, reducing impacts to public health and aquatic biota and favoring the sustainability of the enterprise. Due to limited water resources, it is especially necessary to adopt better management practices that minimize the negative impacts of aquaculture activities.

0

This study investigates the ability of spatial post-discharge mode functionalized kaolin to remove textile dye Reactive Red 2 from aqueous solution compared to that of the raw kaolinite. To fulfill the aim, the removal conditions, including plasma exposure time, processed mode (direct and post-discharge), pH of the aqueous dye solution, initial dye concentration and adsorbent dosage, were investigated. The changes that occur on clay surfaces before and after gliding arc plasma treatment were followed by Fourier transform infrared spectroscopy, scanning electron microscopy and nitrogen physisorption. The point of zero charge and the changes of the textural properties after gliding arc plasma treatment were also examined. The experimental data were analyzed using pseudo-first-order, pseudo-second-order and empirical Elovich models. The diffusion phenomenon was also studied. The results obtained indicate that spatial post-discharge pre-treatment of kaolin deeply influences the functional groups of some of its minerals as well as the morphology and texture of its particles. Consequently, at room temperature (∼30 °C), the maximum adsorption capacities of natural raw kaolin clay were tripled after treatment with gliding arc plasma in spatial post-discharge mode and were almost doubled after the direct treatment mode.