Combined UV-C/H2O2-VUV processes for the treatment of an actual slaughterhouse wastewater

In this study, a three-factor, three-level Box-Behnken design with response surface methodology were used to maximize the TOC removal and minimize the H₂O₂ residual in the effluent of the combined UV-C/H₂O₂-VUV system for the treatment of an actual slaughterhouse wastewater (SWW) collected from one of the meat processing plants in Ontario, Canada. The irradiation time and the initial concentrations of total organic carbon (TOC_o) and hydrogen peroxide (H₂O_2o) were the three predictors, as independent variables, studied in the design of experiments. The multiple response approach was used to obtain desirability response surfaces at the optimum factor settings. Subsequently, the optimum conditions to achieve the maximum percentage TOC removal of 46.19% and minimum H₂O₂ residual of 1.05% were TOC_o of 213 mg L^?1, H₂O_2o of 450 mg L^?1, and irradiation time of 9 min. The attained optimal operating conditions were validated with a complementary test. Consequently, the TOC removal of 45.68% and H₂O₂ residual of 1.03% were achieved experimentally, confirming the statistical model reliability. Three individual processes, VUV alone, VUV/H₂O₂, and UV-C/H₂O₂, were also evaluated to compare their performance for the treatment of the actual SWW using the optimum parameters obtained in combined UV-C/H₂O₂-VUV processes. Results confirmed that an adequate combination of the UV-C/H₂O₂-VUV processes is essential for an optimized TOC removal and H₂O₂ residual. Finally, respirometry analyses were also performed to evaluate the biodegradability of the SWW and the BOD removal efficiency of the combined UV-C/H₂O₂-VUV processes.     

Sequential photochemical-biological degradation of chlorophenols

UV/TiO₂/H₂O₂, UV/TiO₂ and UV/H₂O₂ were compared as pre-treatment processes for the detoxification of mixtures of 4-chlorophenol (4CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) prior to their biological treatment. When each chlorophenol was initially supplied at 50 mg l⁻¹, UV/TiO₂/H₂O₂ treatment supported the highest pollutant removal, COD removal, and dechlorination efficiencies followed by UV/TiO₂ and UV/H₂O₂. The remaining toxicity to Lipedium sativum was similar after all pre-treatments. Chlorophenol photodegradation was always well described by a first order model kinetic (r² > 0.94) and the shortest 4CP, DCP, TCP and PCP half-lives of 8.7, 7.1, 4.5 and 3.3 h, respectively, were achieved during UV/TiO₂/H₂O₂ treatment. No pollutant removal was observed in the controls conducted with H₂O₂ or TiO₂ only. Inoculation of all the photochemically pre-treated mixtures with activated sludge microflora was followed by complete removal of the remaining pollutants. Combined UV/TiO₂/H₂O₂-biological supported the highest detoxification, dechlorination (99%) and COD removal (88%) efficiencies. Similar results were achieved when each chlorophenol was supplied at 100 mg l⁻¹. COD and Cl mass balances indicated UV, UV/H₂O₂, and UV/TiO₂ treatments lead to the formation of recalcitrant photoproducts, some of which were chlorinated.     

Remediation of Kraft E1 and black liquor effluents by biological and chemical processes

We sutdied the application of the bacteria Azotobacter vinellandi on the treatment of effluents from pulp and paper industry. Two types of treatment employing this microorganism were studied: biological treatment isolated and combined with stages of pre- or post-treatment using ozonation or photocatalysis processes. In the biological treatment, the siderophores production by A. vinellandi had a major effect on the efficiency of effluents degradation. Among the different combined treatments, the best results were obtained with the photocatalytic pre-treatment.     

“A Kiss Here and a Kiss There”: Conflict and Collaboration in Environmental Partnerships

Multistakeholder collaboration in the environmental realm has been increasing steadily over the past decade. This trend is responding to several stimuli, including dissatisfaction with current regulatory regimes, a liberal economic climate emphasizing global competitiveness and short-term returns, and the growing roles of the business and nongovernmental organization sectors in the environmental policy arena. This paper grows out of ethnographic research conducted between 1994 and 1998 with four environmental partnerships in Europe and the United States. The research found all of these partnerships to be marked by practices of conflict minimization and diffusion. Drawing upon illustrative data from one of these case studies, a European Union level initiative aimed at enabling sustainable development in Europe, the paper asks why this was the case, especially given the diverse political and economic interests at stake and the history of contentious relations between the sectors in other venues. Employing a theoretical perspective highlighting the sociohistoric factors involved in these processes, the paper suggests that this proclivity toward nonconfrontational behavior stems in part from two sources: a prominent cultural model that conceptualizes the partnership process as fundamentally nonconflictual in nature, and the promotion of the discourse of ecological modernization over other competing discourses. The paper explores some of the implications of this finding and concludes that environmental partnerships characterized by such nonconfrontational practices risk inadvertently encouraging the delegitimization of conflictual approaches to environmental action and engendering a retreat from radical thinking and innovative environmental solutions.     

Social‐Psychological Principles of Community‐Based Conservation and Conservancy Motivation: Attaining Goals within an Autonomy‐Supportive Environment

Abstract: Community‐based natural resource conservation programs in developing nations face many implementation challenges underpinned by social‐psychological mechanisms. One challenge is garnering local support in an economically and socially sustainable fashion despite economic hardship and historical alienation from local resources. Unfortunately, conservationists' limited understanding of the social‐psychological mechanisms underlying participatory conservation impedes the search for appropriate solutions. We address this issue by revealing key underlying social‐psychological mechanisms of participatory conservation. Different administrative designs create social atmospheres that differentially affect endorsement of conservation goals. Certain forms of endorsement may be less effective motivators and less economically and socially sustainable than others. From a literature review we found that conservation initiatives endorsed primarily for nonautonomous instrumental reasons, such as to avoid economic fines or to secure economic rewards, are less motivating than those endorsed for autonomous reasons, such as for the opportunity for personal expression and growth. We suggest that successful participatory programs promote autonomous endorsement of conservation through an administrative framework of autonomy support—free and open democratic participation in management, substantive recognition and inclusion of local stakeholder identity, and respectful, noncoercive social interaction. This framework of the autonomy‐supportive environment (self‐determination theory) has important implications for future research into program design and incentive‐based conservation and identifies a testable social‐psychological theory of conservancy motivation.     

Do these eggs smell funny to you?: an experimental study of egg discrimination by hosts of the social parasite Polyergus breviceps (Hymenoptera: Formicidae)

Social parasites exploit the behaviours of other social species. Infiltration of host systems involves a variety of mechanisms depending on the conditions within the host society and the needs of the social parasite. For many species of socially parasitic ants, colony establishment entails the usurpation of colonies of other species. This frequently involves the eviction or death of the host colony queen and the subsequent adoption of the invading queen. The social parasite queen achieves host worker acceptance by either manipulating the nest-mate recognition processes of the host or undergoing chemical modification. Little is known, however, about how host workers respond to social parasite eggs or whether host species defend against brood parasitism during parasite invasions. Host species are believed to adopt social parasite offspring because the recent common ancestry between many social parasites and their hosts may grant the sharing of certain characteristics such as chemical cues. Use of multiple host species, however, suggests other processes are needed for the social bond between host and parasite young to form. This study reports the findings of adoption bioassays in which eggs from a slave-maker ant, Polyergus breviceps, were offered to workers of two of its host species from unparasitised or newly parasitised nests to determine whether P. breviceps eggs generally elicit rearing behaviours from multiple host species. Comparisons of parasite egg survival until adulthood with conspecific egg survival reveal that workers of both host species, free-living or newly enslaved, do not typically accept slave-maker eggs. Both host species thus have sufficient discriminatory power to reject social parasite eggs although our hydrocarbon analysis indicates parasite eggs may be adapted to their local host species. Combined these results suggest that host rearing of P. breviceps eggs may reflect an evolutionary equilibrium that is maintained by probability and cost of recognition errors.Communicated by L. Sundström     

New parameterization scheme for effective indices for emissions from road transport

The local to regional processes of chemical transformations, washout and dry deposition cannot be directly resolved in global scale models, they rather need to be parameterized. A suitable way to account for the non-linearity, e.g., in chemical transformation processes, is the use of effective emission indices (EEIs). EEI translate the actual (small scale) emissions into input for global scale models, partially accounting for unresolved processes occurring shortly after the release of the emissions.The emissions from the road traffic have some specifics, because of which the concept of deriving EEI from the interaction of an instantaneous plume with the ambient air is perhaps not so convenient. A new parameterization scheme for the EEI from the road transport is suggested in the present paper, based on few simplifying assumptions and introducing the adjoin equations approach, which makes it possible to achieve unified, not depending on the specific emission pattern, procedure for calculating the EEI from road traffic.     

Photochemical degradation and mineralization of 4-chlorophenol

INTENTION, GOAL, SCOPE, BACKGROUND: Since the intermediate products of some compounds can be more toxic and/or refractory than the original compund itself, the development of innovative oxidation technologies which are capable of transforming such compounds into harmless end products, is gaining more importance every day. Advanced oxidation processes are one of these technologies. However, it is necessary to optimize the reaction conditions for these technologies in order to be cost-effective. OBJECTIVE: The main objectives of this study were to see if complete mineralization of 4-chlorophenol with AOPs was possible using low pressure mercury vapour lamps, to make a comparison of different AOPs, to observe the effect of the existence of other ions on degradation efficiency and to optimize reaction conditions. METHODS: In this study, photochemical advanced oxidation processes (AOPs) utilizing the combinations of UV, UV/H2O2 and UV/H2O2/Fe2+ (photo-Fenton process) were investigated in labscale experiments for the degradation and mineralization of 4-chlorophenol. Evaluations were based on the reduction of 4-chlorophenol and total organic carbon. The major parameters investigated were the initial 4-chlorophenol concentration, pH, hydrogen peroxide and iron doses and the effect of the presence of radical scavengers. RESULTS AND DISCUSSION: It was observed that the 4-chlorophenol degradation efficiency decreased with increasing concentration and was independent of the initial solution pH in the UV process. 4-chlorophenol oxidation efficiency for an initial concentration of 100 mgl(-1) was around 89% after 300 min of irradiation in the UV process and no mineralization was achieved. The efficiency increased to > 99% with the UV/H2O2 process in 60 min of irradiation, although mineralization efficiency was still around 75% after 300 min of reaction time. Although the H2O2/4-CP molar ratio was kept constant, increasing initial 4-chlorophenol concentration decreased the treatment efficiency. It was observed that basic pHs were favourable in the UV/H2O2 process. The results showed that the photo-Fenton process was the most effective treatment process under acidic conditions. Complete disappearance of 100 mgl(-1) of 4-chlorophenol was achieved in 2.5 min and almost complete mineralization (96%) was also possible after only 45 min of irradiation. The efficiency was negatively affected from H2O2 in the UV/H2O2 process and Fe2+ in the photo-Fenton process over a certain concentration. The highest negative effect was observed with solutions containing PO4 triple ions. Required reaction times for complete disappearance of 100 mgl(-1) 4-chlorophenol increased from 2.5 min for an ion-free solution to 30 min for solutions containing 100 mgl(-1) PO4 triple ion and from 45 min to more than 240 min for complete mineralization. The photodegradation of 4-chlorophenol was found to follow the first-order law. CONCLUSION: The results of this study showed that UV irradiation alone can degrade 4-CP, although at very slow rates, but cannot mineralize the compound. The addition of hydrogen peroxide to the system, the so-called UV/H2O2 process, significantly enhances the 4-CP degradation rate, but still requires relatively long reaction periods for complete mineralization. The photo-Fenton process, the combination of homogeneous systems of UV/H2O2/Fe2+ compounds, produces the highest photochemical elimination rate of 4-CP and complete mineralization is possible to achieve in quite shorter reaction periods when compared with the UV/H2O2 process. RECOMMENDATIONS AND OUTLOOK: It is more cost effective to use these processes for only purposes such as toxicity reduction, enhancement of biodegradability, decolorization and micropollutant removal. However the most important point is the optimization of the reaction conditions for the process of concern. In such a case, AOPs can be used in combination with a biological treatment systems as a pre- or post treatment unit providing the cheapest treatment option. The AOP applied, for instance, can be used for toxicity reduction and the biological unit for chemical oxygen demand (COD) removal.