I.G. Mason

Implementation of a zero waste program at a university campus

Abstract A zero waste program was established at a university campus in response to grassroots student concern over environmental management issues. The implementation procedure consisted of initial discussions with academic and local authority staff at a university environmental forum, the formation of a working group, the preparation of a funding proposal and the establishment of an externally funded research, educational and promotional program led by an academic staff member. Support from senior management existed in the form of a written environmental policy and a signed commitment to environmental responsibility in tertiary education and university funding support followed the success of the initial funding application. Projects were typically conducted by paid research associates, assisted by student volunteers and supervised by a program leader from the academic staff. Co-operation and support from facilities management staff was obtained on an informal basis. A campus environmental committee was established in order to facilitate communication on environmental matters between the School for the Environment, senior university management, facilities management staff, academic staff and students. In order to enable full program development however, a need for linkages between all sectors involved in the program and the introduction of a formal environmental management system was identified.

Delivering Sustainable Infrastructure that Supports the Urban Built Environment

Sustainable living will require megacity-level infrastructural support designs and paradigms.

Source separation and potential re-use of resource residuals at a university campus

Abstract Source separation systems for solid residuals were introduced to the kitchen/cafeteria and concourse areas of a 9000 student university campus. Over a 5 week in-semester period, the total source separated residuals stream generated in the kitchen/cafeteria area comprised 37% (w/w) food residuals, 3% (w/w) paper, 5% (w/w) plastic, 33% (w/w) “rubbish”, 15% (w/w) cardboard, 1% (w/w) glass, 1% (w/w) newspaper and 5% (w/w) steel cans, whilst the proportions generated in the concourse area were 25% (w/w) food residuals, 4% (w/w) paper, 18% (w/w) plastic, 53% (w/w) “rubbish”. A cross contamination analysis showed that improved source separation performance could increase the recycle rate to 88% (w/w) for the kitchen/cafeteria residuals stream and to 84% (w/w) in the concourse area. Major recyclable materials present in the kitchen/cafeteria “rubbish” stream were food, paper and plastics, whilst food, glass and plastics were the major cross-contaminants in the concourse area. Food streams in both areas were relatively clean. Food residuals were found to be suitable for composting in combination with on-campus green (yard) waste, whilst most other separated streams were either accepted in practice, or technically suitable, for recycling. Improved ongoing education and training is required in order to achieve a high standard of source separation performance from both the kitchen/cafeteria staff and the university community.

Predicting biodegradable volatile solids degradation profiles in the composting process

This paper presents a new method for the prediction of the pattern of biodegradable volatile solids (BVS) degradation in the composting process. The procedure is based on a re-arrangement of the heat balance around a composting system to numerically solve for the rate of BVS carbon (BVS-C) disappearance. Input data for the model was obtained from composting experiments conducted in a laboratory-scale, constant temperature difference (CTD) reactor simulating a section of an aerated static pile, and using a simulated feedstock comprising ostrich feed, shredded paper, finished compost and woodchips. These experiments also provided validation data in the form of exit gas CO(2) carbon (CO(2)-C) profiles. The model successfully predicted the generic shape of experimental substrate degradation profiles obtained from CO(2) measurements, but under the conditions and assumptions of the experiment, the profiles were quantitatively different, giving an over-estimate of BVS-C. Both measured CO(2)-C and predicted BVS-C profiles were moderately to well fitted by a single exponential function, with replicated rate coefficient values of 0.08 and 0.09 d(-1), and 0.06 and 0.07 d(-1), respectively. In order to explore the underlying shape of the profiles, measured and predicted data at varying temperature were corrected to a constant temperature of 40 degrees C, using the temperature correction function of Rosso et al. [Rosso, L., Lobry, J.R., and Flandrois, J.P., 1993. An unexpected correlation between cardinal temperatures of microbial growth highlighted by a new model. Journal of Theoretical Biology, 162, 447-463], with cardinal temperatures of 5, 59 and 85 degrees C. Multi-phase profiles were generated for both the measured CO(2)-C and the predicted BVS-C data in this case. However, when alternative cardinal temperatures of 5, 55 and 80 degrees C, or 5, 50 and 80 degrees C, were used, the predicted profiles assumed an exponential shape, and excellent fits were obtained using a double exponential function. These findings support the argument that a substrate degradation curve generated under laboratory conditions at 40 degrees C, would, given correct cardinal temperatures, generate a correct substrate degradation profile under varying temperature conditions and that this in turn would enable an accurate and precise prediction of the temperature profile, using a heat and mass balance approach. In order to realise this prospect, it is proposed that further work to obtain experimental data under completely mixed conditions, more accurately estimate the overall heat transfer coefficient and obtain correct values for the cardinal temperatures used in the temperature correction function, is required.

The Carbon Neutral Public Sector

Abstract This paper argues for research into the effectiveness of government strategies for a ‘carbon neutral public sector’. We review initiatives in three OECD countries: New Zealand, Australia and the UK. In all jurisdictions, government agencies have consistently stressed ‘leading by example’ as a rationale for adoption. ‘Direct mandate’ by the Prime Minister (NZ); ‘organic development’ from wider central government sustainability initiatives (UK); and a more ‘laissez faire’ approach by Australian Federal and State Governments, were identified as the general pathways leading to implementation. Our assessment indicates: a lack of understanding of the implementation process for carbon neutrality; a need to identify and critically examine the ‘offset threshold’ at which mitigation efforts cease and offsetting is adopted; an absence of any evaluation of the ‘leading by example’ rationale; a lack of inter-country comparisons; a gap in understanding the relationship with economic and social aspects of sustainability; and a need to evaluate the utility of core government departments as the focus of carbon accounting. We urge colleagues to consider research in this area with a view to contributing to the interdisciplinary solutions which we believe are required.

Composting High Moisture Content Bovine Manure Using Passive Aeration

High moisture content bovine manure from a farm dairy (milking parlor) holding yard was successfully composted in a pilot-scale passively aerated system, without prior dewatering, using sawdust or paper as amendments and woodchips as the bulking agent. The amendments were used to adjust the manure total solids content from an initial average level of 10% (w/w) to approximately 20% (w/w), prior to structural conditioning with the woodchips. Initial total solids levels for the mixture were approximately 35% (w/w) in both cases. Rapid temperature increases were obtained and peak values of 73.9°C and 79.5°C were recorded for the sawdust and paper amendment systems respectively. Thermophilic conditions were maintained in the pile centers for 17-54 days and temperatures above 55°C for 6-37 days. However, susceptibility to environmental influences was demonstrated, with downward temperature excursions, coincident with cool ambient conditions, recorded on several occasions. Final mixture moisture levels were approximately 56-58% (w/w) for the sawdust amendment system and 44-49% (w/w) for the paper amendment system. Marked vertical differences in moisture concentration were found in both manure/amendment/woodchips systems, with notably drier conditions in the lower layers of the paper amendment piles. Predicted initial ratios of available energy to total moisture were 438-949 and 563-1146 cal/g-H2O for the sawdust and paper amendment systems respectively, depending on the biodegradability factor assumed for the wood-chips component. Energy usage values of 1730 and 1344 cal/g-H2O-removed were determined for the sawdust amendment system, based on measured VS and moisture changes. Overall biodegradability factors for the sawdust amendment replicates, based on volatile solids removal, were 0.29 and 0.33 and the composting performance of both systems results indicated that the woodchips had likely contributed substantially to the biodegradable volatile solids pool. Overall disinfection performance after 70-74 days was limited, with a maximum coliform removal of 2.2 log MPN/g-TS. Composting of manure and sawdust alone resulted in a slow rate of temperature rise and incomplete composting after 90 days. Further work is suggested in order to explore the effect of pile insulation or partial enclosure and to study moisture distribution, woodchips biodegradability, materials handling and disinfection performance issues

Managing carbon in times of political change: the rise and fall of the New Zealand Carbon Neutral Public Service program

Abstract The New Zealand (NZ) government, under Prime Minister Helen Clarks Labour-led administration, sought in 2007 to move government core organisations towards carbon neutrality. In late 2008, the NZ government changed from a Labour-led to a National-led (traditionally more conservative) government, and this saw a shift in its carbon neutrality agenda, including the dismantling of the NZ Carbon Neutral Public Service (CNPS) program. In this paper, we explore the experiences of public servants from the lead core agencies involved in the CNPS program to investigate the rise and fall of the program in a time of political change, and to assess the evidence for Cabinet Minister Dr Nick Smiths rationale for program termination. Our research approach comprises a series of semi-structured interviews with the lead core agencies involved in the CNPS program, as well as the program champion, former Prime Minister, Helen Clark. We find that, in spite of initial challenges, the CNPS program appeared to deliver emission reductions, financial cost savings and a range of non-financial benefits. Whilst program costs would have likely outweighed the financial savings, due to high set-up and offsetting costs, we conclude that Nick Smiths case is unsupported by the evidence.

Composting of green waste shredded by a crush/cut roller versus a low speed counter-rotating shear shredder

Green waste was shredded at a commercial composting site by a conventional commercial low speed counter-rotating shear type shredder and an alternative shredder, a crush/cut roller mounted on and powered by a tracked excavator. Material from both shredding systems showed similar dry weight and dry bulk density patterns across a broad particle size distribution range. The crush/cut roller produced significantly different (p < 0.05) quantities of material in the 10-25 mm and 75-100 mm particle size ranges, whilst dry bulk density values were significantly different in the 16-25 mm range only. Over a three month windrow composting period, dry weight percentage and dry bulk density values from both systems tended to increase toward the lower end of the particle size range and decrease toward the higher end of the particle size range and were, with one exception, not significantly different. These values were similar in magnitude to those for material from commercial green waste composting windrows. Temperature profiles were comparable in both systems and indicated the existence of thermophilic conditions within each windrow for over 50 days, whilst product stability, as indicated by specific oxygen uptake rates, was the same for both treatments. It was concluded that any differences in particle size distribution between the two shredding systems were not important in relation to the biological aspects of the composting process. Development of a simple compost maturity test based on particle size profiling is suggested. It is proposed that the alternative, crush/cut roller, approach to green waste shredding could potentially reduce the economic threshold for organic recycling and allow many smaller communities to benefit from this environmentally sound waste management practice.

CHARACTERISTICS OF FARM DAIRY YARD WASTEWATER RELATED TO BIOLOGICAL NUTRIENT REMOVAL

Factors affecting the treatability of farm dairy yard wastewater for biological nutrient removal were investigated over a 126–day period. Average CODvfa:TN, CODvfa:P, and alkalinity:TKN ratios were 0.7:1, 3.9:1, and 2.2:1, respectively. The CODvfa:TN and CODvfa:P ratios were low in comparison to levels required for optimal denitrification and phosphorus uptake. However, the high BOD5 levels present indicated the potential for prefermentation to increase volatile fatty acid levels to acceptable levels. Alkalinity levels were low with respect to recommendations for both stand–alone nitrification and combined nitrification/denitrification processes. In order for CODvfa:TN, CODvfa:P, and alkalinity:TKN requirements to be met without pre–fermentation, removals of nitrogen and phosphorus during primary sedimentation ranging from 39% to 89% would be required.

VOLATILE FATTY ACID PRODUCTION FROM FARM DAIRY WASTEWATER

Batch and semi–continuous prefermentation of farm dairy wastewater was investigated under laboratory conditions at 20.C. In the batch trials, volatile fatty acid production commenced following a 0 to 1 day lag time, and peak CODvfa concentrations of 1945 to 1960 g/m3 occurred after 8 to 10 days. A maximum yield of 0.39 g–CODvfa/g–BOD5 was obtained at 10 days, with peak volatile fatty acid production rates of 26 to 28 g/m3 hr measured after 2 to 4 days fermentation. Acetic acid was the dominant VFA produced, reaching a maximum of 64% to 67% (w/w) after 8 to 10 days, followed by propionic, butyric, and valeric acids at 18% to 20%, 9% to 10%, and 5% to 6%, respectively. Volatile fatty acid fractions remained relatively constant after 3 to 6 days. Peak ratios of CODvfa:N and CODvfa:P of 2.6:1 and 23.4:1 were estimated for prefermented farm dairy wastewater. These allowed a CODvfa:P criterion within the range 8:1 to 20:1 for phosphorus removal to be met. However, the CODvfa:N ratio alone was considered insufficient for optimal denitrification performance with this wastewater. Increasing CODvfa increments were obtained over 28 days semi–continuous prefermentation incorporating sludge retention, followed by failure at 35 days. A solids retention time of 10 to 21 days was indicated as a basis for further investigation to determine optimal process operating conditions for the prefermentation of farm dairy wastewater.