Scale-up of electrochemical oxidation system for treatment of produced water generated by Brazilian petrochemical industry

Scale-up of anodic oxidation system is critical to the practical application of electrochemical treatment in bio-refractory organic wastewater treatment. In this study, the scale-up of electrochemical flow system was investigated by treating petrochemical wastewater using platinized titanium (Ti/Pt) and boron-doped diamond (BDD) anodes. It was demonstrated that flow cell was successfully scaled-up because when it was compared with batch mode (Rocha et al. 2012b), higher performances on organic matter removal were achieved. Under the suitable operating conditions and better anode material, the chemical oxygen demand (COD) of petrochemical wastewater was reduced from 2,746 to 200 mg L^?1 within 5 h with an energy consumption of only 56.2 kWh m^?3 in the scaled-up BDD anode system. These results demonstrate that anode flow system is very promising in practical bio-refractory organic wastewater treatment.     

Mitigation of odor causing emissions—Bench-scale investigation

Emissions of malodors are considered to be the greatest threat to the compost industry. In work presented here, several simple odor mitigation alternatives were investigated for their effectiveness in preventing the release of common odorants, such as terpenes, ammonia, and reduced sulfur compounds. The mitigation methods studied included the use of a blanket of finished compost, compost amendment mixed within the feedstock, odor neutralizing agents (ONAs), and oxygen release compounds (ORCs). Among the mitigation alternatives investigated in this study, the use of finished compost as a blanket and finished compost as an amendment yielded the most conclusive and significant results. Both of these alternatives yielded a substantial emission reduction for terpenes, ammonia, and reduced sulfur compounds. The application of finished compost blanket resulted in up to 95% reduction of terpene and 25% reduction of ammonia emissions. Blending the feedstock with finished compost also provided substantial reduction of terpene emissions ranging from 73.6 to 93.1% at the 24% blending ratio, and up to 85% ammonia reduction a the 35% blending ratio. Use of finished compost also provided 75% lower reduced sulfur compound emissions at the 12% blending ratio. Misting and application of odor neutralizing agents did not result in any consistent reduction in emissions for any of the odorous compounds tested.

Implications The odor emissions from composting are often considered to be the biggest threat to composting facilities. Because most facilities cannot afford enclosures and contained composting vessels, there is a need to inexpensively and effectively control the odor emissions from composting facilities. The findings of this research can lead the way for efforts to control odor easily and cost effectively. In fact, the application of a compost blanket for odor control is already gaining acceptance by the composting industry.     

Radical precursors and related species from traffic as observed and modeled at an urban highway junction

Nitrous acid (HONO) and formaldehyde (HCHO) are important precursors for radicals and are believed to favor ozone formation significantly. Traffic emission data for both compounds are scarce and mostly outdated. A better knowledge of today's HCHO and HONO emissions related to traffic is needed to refine air quality models. Here the authors report results from continuous ambient air measurements taken at a highway junction in Houston, Texas, from July 15 to October 15, 2009. The observational data were compared with emission estimates from currently available mobile emission models (MOBILE6; MOVES [MOtor Vehicle Emission Simulator]). Observations indicated a molar carbon monoxide (CO) versus nitrogen oxides (NO_x) ratio of 6.01 ± 0.15 (r ² = 0.91), which is in agreement with other field studies. Both MOBILE6 and MOVES overestimate this emission ratio by 92% and 24%, respectively. For HCHO/CO, an overall slope of 3.14 ± 0.14 g HCHO/kg CO was observed. Whereas MOBILE6 largely underestimates this ratio by 77%, MOVES calculates somewhat higher HCHO/CO ratios (1.87) than MOBILE6, but is still significantly lower than the observed ratio. MOVES shows high HCHO/CO ratios during the early morning hours due to heavy-duty diesel off-network emissions. The differences of the modeled CO/NO_x and HCHO/CO ratios are largely due to higher NO_x and HCHO emissions in MOVES (30% and 57%, respectively, increased from MOBILE6 for 2009), as CO emissions were about the same in both models. The observed HONO/NO_x emission ratio is around 0.017 ± 0.0009 kg HONO/kg NO_x which is twice as high as in MOVES. The observed NO₂/NO_x emission ratio is around 0.16 ± 0.01 kg NO₂/kg NO_x, which is a bit more than 50% higher than in MOVES. MOVES overestimates the CO/CO₂ emission ratio by a factor of 3 compared with the observations, which is 0.0033 ± 0.0002 kg CO/kg CO₂. This as well as CO/NO_x overestimation is coming from light-duty gasoline vehicles.

Implications: Nitrous acid (HONO) and formaldehyde (HCHO) are important precursors for radicals that ultimately contribute to ozone formation. There still exist uncertainties in emission sources of HONO and HCHO and thus regional air quality modeling still tend to underestimate concentrations of free radicals in the atmosphere. This paper demonstrates that the latest U.S. Environmental Protection Agency (EPA) traffic emission model MOVES still shows significant deviations from observed emission ratios, in particular underestimation of HCHO/CO and HONO/NO_x ratios. Improving the performance of MOVES may improve regional air quality modeling.     

Evaluation of best management practice products in preventing discharge of metals: a laboratory evaluation

Heavy metal accumulation in soil poses serious environmental and health risks, as metals are carried with eroded soils. In this study, 17 different soil erosion and sediment control products were investigated for their effectiveness in controlling transport of particulate heavy metals (Cu, Zn, Pb, Cd). Among the treatments investigated, wood mulch and tackifiers were found to be the most effective in reducing total suspended solids (TSS) and total heavy metal losses. They reduced TSS to an undetectable level during short-term simulation tests. Paper mulch was the only treatment that had no significant reduction in both total metal loss and TSS. Fiber rolls, silt fences, and gravel bags were effective in reducing sediment loss. Although the netting/blanket treatments were not effective in reducing total metal discharge, they significantly reduced sediment loss compared with the control.     

Capacity of biochar application to maintain energy crop productivity: soil chemistry, sorghum growth, and runoff water quality effects

Pyrolysis of crop biomass generates a by-product, biochar, which can be recycled to sustain nutrient and organic C concentrations in biomass production fields. We evaluated effects of biochar rate and application method on soil properties, nutrient balance, biomass production, and water quality. Three replications of eight sorghum [ (L.) Moench] treatments were installed in box lysimeters under greenhouse conditions. Treatments comprised increasing rates (0, 1.5, and 3.0 Mg ha) of topdressed or incorporated biochar supplemented with N fertilizer or N, P, and K fertilizer. Simulated rain was applied at 21 and 34 d after planting, and mass runoff loss of N, P, and K was measured. A mass balance of total N, P, and K was performed after 45 d. Returning 3.0 Mg ha of biochar did not affect sorghum biomass, soil total, or Mehlich-3-extractable nutrients compared to control soil. Yet, biochar contributed to increased concentration of dissolved reactive phosphorus (DRP) and mass loss of total phosphorus (TP) in simulated runoff, especially if topdressed. It was estimated that up to 20% of TP in topdressed biochar was lost in surface runoff after two rain events. Poor recovery of nutrients during pyrolysis and excessive runoff loss of nutrients for topdressed biochar, especially K, resulted in negative nutrient balances. Efforts to conserve nutrients during pyrolysis and incorporation of biochar at rates derived from annual biomass yields will be necessary for biochar use in sustainable energy crop production.     

Carbamazepine, carbamazepine epoxide and dihydroxycarbamazepine sorption to soil and occurrence in a wastewater reuse site in Tunisia

Although a number of manufactured nanoparticles are applied for the medical and clinical purposes, the understanding of interaction between nanomaterials and biological systems are still insufficient. Using nematode Caenorhabditis elegans model organism, we here investigated the in vivo toxicity or safety of hydroxylated fullerene nanoparticles known to detoxify anti-cancer drug-induced oxidative damages in mammals. The survival ratio of C. elegans rapidly decreased by the uptake of nanoparticles from their L4 larval stage with resulting in shortened lifespan (20 d). Both reproduction rate and body size of C. elegans were also reduced after exposure to 100 μg mL⁻¹ of fullerol. We found ectopic cell corpses caused by apoptotic cell death in the adult worms grown with fullerol nanoparticles. By the mutation of core pro-apoptotic regulator genes, ced-3 and ced-4, these nanoparticle-induced cell death were significantly suppressed, and the viability of animals consequently increased despite of nanoparticle uptake. The apoptosis-mediated toxicity of nanoparticles particularly led to the disorder of digestion system in the animals containing a large number of undigested foods in their intestine. These results demonstrated that the water-soluble fullerol nanoparticles widely used in medicinal applications have a potential for inducing apoptotic cell death in multicellular organisms despite of their antioxidative detoxifying property.     

Bioindication of volatile elements emission by the Puyehue-Cordón Caulle (North Patagonia) volcanic event in 2011

The emission of volatile pollutants from the volcanic eruption of the Puyehue-Cordón Caulle complex (North Patagonia Andean Range) that started in June 4th, 2011, was investigated by bioindication means with the epyphytic fruticose lichen Usnea sp. The elemental composition of pooled samples made up with 10 lichen thalli were analysed by Instrumental Neutron Activation Analysis. Eleven sampling sites were selected within the impacted region at different distance from the volcanic source. Five sites were selected as they were already sampled in a previous study prior to the eruption. Two other new sampling sites were selected from outside the impacted zone to provide non-impacted baseline sites.The elements associated with the lichen incorporation of particulate matter (PM) of geological origin were identified by linear correlation with a geochemical tracer (Sm concentrations). The elements associated with PM uptake were Ce, Eu, Fe, Hf, La, Lu, Na, Nd, Sb, Sc, Se, Ta, Tb, Th, U, and Yb. Arsenic and Cs concentrations showed contributions exceeding the PM fraction in sites near the volcanic centre, also higher than the baseline concentrations, which could be associated with permanent emissions from the geothermal system of the Puyehue-Cordón Caulle complex. The lichen concentrations of Ba, Ca, Co, Hg, K, Rb, Sr, and Zn were not associated with the PM, not showing higher concentrations in the sites nearby the volcanic source or respect to the baseline values either. Therefore, there is no indication of the emission of volatile forms of these elements in the lichen records. The lichen records only identified Br volatile emissions associated with the Puyehue-Cordón Caulle complex eruption in 2011.     

Apple snails and their endosymbionts bioconcentrate heavy metals and uranium from contaminated drinking water

Purpose

The differential ability of apple snail tissues, endosymbionts, and eggs to bioaccumulate several metals (Sb, As, Ba, Br, Zn, Cr, Fe, Hg, Se, and U) was investigated.

Methods

Metal concentrations were determined by neutron activation analysis in several tissues, endosymbionts, and eggs from mature apple snails cultured in either drinking water or reconstituted water (prepared with American Society for Testing and Materials type I water).

Results

The highest bioconcentration factors (BCFs) in the midgut gland were found for Ba, Zn, Se, As, U, Br, and Hg (in decreasing order), while the highest in the kidney were for Ba, Br, and Hg. The foot showed the highest BCFs for Ba, Hg, Br, and Se (in decreasing order). Calcified tissues (uterus, shell) and eggs showed low BCFs, except for Ba. Both C corpuscles and gland tissue showed statistically higher BCFs than K corpuscles for Ba, Fe, U, Br, and Sb. The concentration of most of the studied elements was significantly lower in tissues and endosymbionts obtained from snails cultured in reconstituted water instead of drinking water. Snails cultured in reconstituted water and then exposed or not to Hg, As, and U (at the maximum contaminant level allowed by the US Environmental Protection Agency) also resulted in high levels accumulated in midgut gland, endosymbionts and kidney.

Conclusions

Our findings suggest that the midgut gland (and the symbionts contained therein), the kidney, and the foot of Pomacea canaliculata may be useful bioindicators of Hg, As and U pollution in freshwater bodies and that the unrestricted use of ampullariid snails as human and animal food must be considered with caution..     

Feasibility of vermicomposting dairy biosolids using a modified system to avoid earthworm mortality

Abstract

A laboratory study was conducted to examine the feasibility of vermicomposting dairy biosolids (dairy sludge), either alone or with either of the bulking agents ‐ cereal straw or wood shavings, using the epigeic earthworm ‐ Eisinea andrei. Earthworms added directly to these three substrates died within 48 hours. A system was developed to overcome the toxic effect of unprocessed dairy biosolids. The substrates were placed over a layer of vermicomposted sheep manure into which the earthworms were inoculated. Within two weeks, all earthworms were within the upper layer of substrate. Compared to sheep manure which is a favourable substrate for vermicomposting, the three substrates containing dairy biosolids were more effective in supporting earthworm growth and reproduction. The final products obtained after 63 days of vermicomposting had 39–53% less organic carbon than the initial substrates. Organic fractionation indicated that vermicomposting increased the stability of the materials to biological decomposition. The vermicomposts obtained from the three substrates with dairy biosolids had low heavy metal contents and electrical conductivities, and did not inhibit plant growth when compared with a commercial vermicompost in a bioassay.     

Chiral signature of venlafaxine as a marker of biological attenuation processes

The chiral signature of the antidepressant venlafaxine was used in this study to gain insight into biological attenuation processes and to differentiate abiotic and biotic transformation processes in water. Laboratory scale experiments revealed that sorption and phototransformation processes were not enantioselective while venlafaxine was enantioselectively biotransformed into O-desmethylvenlafaxine. The enantiomeric fraction (EF) variations of venlafaxine appeared to be proportional to its microbial fractional conversion. Enantioselective biotransformation of venlafaxine was also investigated in a eutrophic French river. Venlafaxine was found to be racemic at the output of the main wastewater treatment plant discharging into the river, independently of the sampling date during the year. An analysis of EF variations might provide evidence of biodegradation along a 30 km river stretch.