Development of a new risk-based framework to guide investment in water quality monitoring

An innovative framework for optimising investments in water quality monitoring has been developed for use by water and environmental agencies. By utilising historical data, investigating the accuracy of monitoring methods and considering the risk tolerance of the management agency, this new methodology calculates optimum water quality monitoring frequencies for individual water bodies. Such information can be applied to water quality constituents of concern in both engineered and natural water bodies and will guide the investment of monitoring resources. Here we present both the development of the framework itself and a proof of concept by applying it to the occurrence of hazardous cyanobacterial blooms in freshwater lakes. This application to existing data demonstrates the robustness of the approach and the capacity of the framework to optimise the allocation of both monitoring and mitigation resources. When applied to cyanobacterial blooms in the Swan Coastal Plain of Western Australia, we determined that optimising the monitoring regime at individual lakes could greatly alter the overall monitoring schedule for the region, rendering it more risk averse without increasing the amount of monitoring resources required. For water resources with high-density temporal data related to constituents of concern, a similar reduction in risk may be observed by applying the framework.     

Food waste treatment in a community center

For urban community composting centers, the proper selection and use of bulking agent is a key element in not only the cost but also the quality of the finished compost. Besides wood chips (WC) widely used as BA, readily usable cereal residue pellets (CRP) can provide biodegradable carbon and sufficient free air space (FAS) to produce stabilizing temperatures. The objective of the present project was to test at a community center, the effectiveness of CRP in composting food waste (FW). Two recipes were used (CRP with and without WC) to measure: FAS; temperature regimes, and; losses in mass, water, carbon and nitrogen. Both recipes were composted during three consecutive years using a 2 m³ commercial in-vessel composter operated in downtown Montreal (Canada). For all recipes, FAS exceeded 30% for moisture content below 60%, despite yearly variations in FW and BA physical properties. When properly managed by the center operator, both FW and CRP compost mixtures with and without WC developed within 3 days thermophilic temperatures exceeding 50 °C. The loss of total mass, water, carbon and nitrogen was quite variable for both recipes, ranging from 36% to 54%, 42% to 55%, 48% to 65%, and 4% to 55%, respectively. The highest loss in dry mass, water and C was obtained with FW and CRP without WC aerated to maintain mesophilic rather than thermophilic conditions. Although variable, lower nitrogen losses were obtained with CRP and WC as BA, compared to CRP alone, as also observed during previous laboratory trials. Therefore and as BA, CRP can be used alone but nitrogen losses will be minimized by adding WC. Compost stabilization depends on operator vigilance in terms of aeration. The measured fresh compost density of 530-600 kg/m³ indicates that the 2 m³ in-vessel composter can treat 6.5 tons of FW/year if operated during 7 months.     

Characterization of food waste and bulking agents for composting

The characterization of food waste (FW) and locally available bulking agents (BA) are a prerequisite to optimizing compost recipes. This study measured the variation in FW characteristics (pH, dry matter (DM), carbon (C), wet bulk density and Total Kjeldahl Nitrogen (TKN)) produced by a restaurant and a community kitchen in downtown Montreal, Canada from May to August 2004. The project also measured the mass of FW produced by another restaurant and a group of 20-48 households, from June to August 2004. Locally available BA (hay, straw, pine wood shavings, cardboard, left over cattle feed and wheat residue pellets) were also characterized to formulate composting recipes based on the FW characteristics observed during a period representative of winter and summer conditions. Residential and restaurant FW characteristics varied significantly over the summer months, although the mass produced remained constant at 0.61 and 0.56 kg capita(-1)day(-1), respectively. In addition, the number of customers served by the restaurant increased by nearly 50% from June to August. The BA with the highest moisture adsorption capacity was found to be the wheat residue pellets, followed by chopped straw. Wheat residue pellets, chopped hay and left over cattle feed all presented a balanced C/N ratio. Wheat residue pellets and wheat straw, chopped hay and cardboard demonstrated neutral pH values. Based on the variable FW characteristics and monthly production rates, the formulation of recipes indicates that compost facilities must be flexible enough to handle seasonal variations of as much as 50% by volume.     

Biodegradation of pentyl amine and aniline from petrochemical wastewater

The objectives of the project were to isolate a bacterial strain capable of degrading pentyl amine and aniline and to define the optimal pentyl amine and aniline degradation conditions for this bacterial strain. The bacterial strain was isolated from activated sludge obtained from a Northeastern China treatment facility for petrochemical wastewater rich in pentyl amine and aniline. Once the strain was isolated, five triplicate (5) batch tests were used to establish the conditions for maximum pentyl amine and aniline degradation, by varying one at a time the following five factors: temperature, pH, reaction time, pollutant concentrations and aeration rate. In a final test, oil refinery sludge was inoculated with the strain and tested for the degradation of pentyl amine and aniline under optimal conditions, while observing the degradation pathway of pentyl amine and aniline. The isolated strain, PN1001, is a member of the Pseudomonas species and it was capable of degrading pentyl amine and aniline. The optimal reactor conditions for the degradation of a mixture of pentyl amine and aniline, at a concentration ranging between 150 and 200mg/L, were found to be 30 degrees C at a pH of 7.0, under a reaction time of 24h and a maximum solution dissolved oxygen level of 6 mgO(2)/L. Under such conditions, the strain PN1001 degraded 93% and 89% of the pentyl amine and aniline, respectively, aniline being more toxic and demonstrating a more complex degradation pathway. The strain PN1001 degraded more contaminants when both were present because of the pi and sigma electron cloud coordination functions of aniline and pentyl amine, respectively, presumed to reduce the toxic effect of aniline. Once inoculated with the strain, oil refinery sludge degraded 93% and 88% of the pentyl amine and aniline, compared to the strain alone which degraded 72% and 82%, likely because of the sludge's buffering effect against the toxic environment.     

Predicted growth of world urban food waste and methane production.

Landfill gas emissions are one of the largest anthropogenic sources of methane especially because of food waste (FW). To prevent these emissions growing with world population, future FW best management practices need to be evaluated. The objective of this paper was therefore to predict FW production for 2025 if present management practices are maintained, and then, to compare the impact of scenario 1: encouraging people to stay in rural areas and composting 75% of their FW, and; of scenario 2, where in addition to scenario 1, composting or anaerobically digesting 75% of urban FW (UFW). A relationship was established between per capita gross domestic product (GDP) and the population percentage living in urban areas (%UP), as well as production of municipal solid waste (MSW) and UFW. With estimated GDP and population growth per country, %UP and production of MSW and UFW could be predicted for 2025. A relatively accurate (R(2) > 0.85) correlation was found between GDP and %UP, and between GDP and mass of MSW and FW produced. On a global scale, MSW and UFW productions were predicted to increase by 51 and 44%, respectively, from 2005 to 2025. During the same period, and because of its expected economic development, Asia was predicted to experience the largest increase in UFW production, of 278 to 416 Gkg. If present MSW management trends are maintained, landfilled UFW was predicted to increase world CH4 emissions from 34 to 48 Gkg and the landfill share of global anthropogenic emissions from 8 to 10%. In comparison with maintaining present FW management practices, scenario 1 can lower UFW production by 30% and maintain the landfill share of the global anthropogenic emissions at 8%. With scenario 2, the landfill share of global anthropogenic emissions could be further reduced from 8 to 6% and leachate production could be reduced by 40%.     

Precipitation of swine and cattle manure phosphorous using limestone dust

The effectiveness of SPS and PULPRO, fine limestone dusts, in precipitating swine and dairy manure phosphorous (P) was determined in the laboratory. Both manures were sieved before being treated with limestone, to reproduce the treatment of mechanically separated manure and to observe the precipitation effect of limestone without that of the large manure solid particles. P precipitation was optimized by varying precipitation conditions (propeller blade speeds, mixing time and limestone levels) and limestone particle size. P precipitation was optimized using a propeller blade mixing speed of 0.3 m s(-1) for at least 5 minutes, using 3% limestone (dry limestone mass over wet manure mass). In terms of particle size, PULPRO 20 (limestone with a particle size of 0.02 mm) produced the most P precipitation and the smallest volume and mass of sludge, as compared to PULPRO 10, PULPRO 3 and SPS (limestone with a particle size of 0.01, 0.003 and 0.3 to 0.003 mm, respectively). For both 9.5% TS (total solids) dairy and 8.8% TS swine manure, mechanical separation followed by limestone precipitation concentrated 90% of manure TS and TP in a sludge volume representing 45% of the initial raw manure mass.     

Latino social network dynamics and the Hurricane Katrina disaster

The aim of this qualitative research was to examine the dynamics of existing and emerging social networks among Latino survivors of Hurricane Katrina. Data were generated through individual, in-depth interviews conducted with 65 Latinos within six months of the storm striking the Gulf Coast of the United States in August 2005. The findings illustrated both the role of social networks in gathering information, making decisions and accessing resources, and how these existing social networks were disrupted and strained by overwhelming needs. Broader structural issues, including poverty and a lack of transportation, combined with marginalised status as immigrants, further constrained access to essential information and resources. In response, new, if temporary, social networks emerged, based primarily on shared nationality, language, and a sense of collective commitment. Practice implications include the need to consider the social network dynamics of marginalised groups in developing innovative strategies to overcome structural barriers to accessing resources essential for disaster preparedness and survival.     

Effectiveness of three bulking agents for food waste composting

Rather than landfilling, composting the organic fraction of municipal solid wastes recycles the waste as a safe and nutrient enriched soil amendment, reduces emissions of greenhouse gases and generates less leachate. The objective of this project was to investigate the composting effectiveness of three bulking agents, namely chopped wheat (Triticum) straw, chopped mature hay consisting of 80% timothy (milium) and 20% clover (triphullum) and pine (pinus) wood shavings. These bulking agents were each mixed in duplicates at three different ratios with food waste (FW) and composted for 10 days using prototype in-vessel composters to observe their temperature and pH trends. Then, each mixture was matured in vertical barrels for 56 days to measure their mass loss and final nutrient content and to visually evaluate their level of decomposition. Chopped wheat straw (CWS) and chopped hay (CH) were the only two formulas that reached thermophilic temperatures during the 10 days of active composting when mixed with FW at a wet mass ratio of 8.9 and 8.6:1 (FW:CWS and FW:CH), respectively. After 56 days of maturation, these two formulas were well decomposed with no or very few recognizable substrate particles, and offered a final TN exceeding the original. Wood shavings (WS) produced the least decomposed compost at maturation, with wood particles still visible in the final product, and with a TN lower than the initial. Nevertheless, all bulking agents produced compost with an organic matter, TN, TP and TK content suitable for use as soil amendment.     

Odorous gaseous emissions as influence by process condition for the forced aeration composting of pig slaughterhouse sludge

Compost sustainability requires a better control of its gaseous emissions responsible for several impacts including odours. Indeed, composting odours have stopped the operation of many platforms and prevented the installation of others. Accordingly, present technologies collecting and treating gases emitted from composting are not satisfactory and alternative solutions must be found. Thus, the aim of this paper was to study the influence of composting process conditions on gaseous emissions. Pig slaughterhouse sludge mixed with wood chips was composted under forced aeration in 300 L laboratory reactors. The process conditions studied were: aeration rate of 1.68, 4.03, 6.22, 9.80 and 13.44 L/h/kg of wet sludge; incorporation ratio of 0.55, 0.83 and 1.1 (kg of wet wood chips/kg of wet sludge), and; bulking agent particles size of <10, 10 < 20 and 20 < 30 mm. Out-going gases were sampled every 2 days and their composition was analysed using gas chromatography coupled with mass spectrometry (GC–MS). Fifty-nine compounds were identified and quantified. Dividing the cumulated mass production over 30 days of composting, by odour threshold, 9 compounds were identified as main potential odour contributors: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone, 1-propanol-2-methyl, dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide and acetophenone. Five gaseous compounds were correlated with both aeration rate and bulking agent to waste ratio: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone and 1-propanol-2-methyl. However, dropping the aeration rate and increasing the bulking agent to waste ratio reduced gaseous odour emissions by a factor of 5–10, when the required threshold dilution factor ranged from 10⁵ to 10⁶, to avoid nuisance at peak emission rates. Process influence on emissions of dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide were poorly correlated with both aeration rate and bulking agent to waste ratio as a reaction with hydrogen sulphide was suspected. Acetophenone emissions originated from the wood chips. Olfactory measurements need to be correlated to gaseous emissions for a more accurate odour emission evaluation.