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Item Valuing the benefits of a small community sewerage system in the coastal environment : a thesis submitted in partial fulfilment of the requirements for the degree of Masters of Applied Economics at Massey University(Massey University, 1999) Moore, Richard RalphA community sewerage system is a public good which society derives a wide range of benefits from. Because a community sewerage system is a public good, it is normally provided under the direction and control of a local authority. A local authority contemplating providing a community sewerage system in a small coastal community, must consider whether the welfare of the community will increase as a result. To do this it needs to consider the total economic costs and benefits that the community might incur or gain from building a small community sewerage system. In the coastal environment the value of many of the benefits a community sewerage system would provide can not be observed in commercial markets. This research aimed to provide local authority decision-makers with a way to value the benefits of a small community sewerage system in the coastal environment. To achieve this the contingent valuation method was used in the form of a mail questionnaire with specific reference to the circumstances of small coastal communities. Application of the questionnaire was illustrated using three small New Zealand coastal communities, Russell, Tapeka and Horeke. The questionnaire was mailed to households and businesses in these communities to solicit their willingness to pay for the benefits of a proposed community sewerage system. An average return rate of 50% was obtained. The information and results obtained from the questionnaires showed that they can provide valuable information. In particular, information for a decision-maker wishing to determine if community sewerage is economically efficient in a small coastal community. The average value per fortnight that respondents from Russell, Tapeka, and Horeke placed on the benefits of a community sewerage system was $16.60, $15.97 and $9.75 respectively. For each community, the average value was not sufficient to cover the cost of the proposed community sewerage system. Nevertheless, the authority managing the sewerage issues in Russell, Tapeka, and Horeke gained beneficial insights to adopt the best plan of action for sewerage in each community.Item Sewage sludge disposal : the composting option : thesis presented in fulfillment of the requirements for the degree of Master of Technology in biotechnology at Massey University(Massey University, 1988) Bogoni, CarloThe objective of the present studies was to explore the possibility of employing composting as a mean of sewage sludge stabilization. A series of composting experiments were performed using dewatered secondary activated sewage sludge from a domestic wastewater treatment plant in New Plymouth, New Zealand. These trials have been carried out treating the sludge in both open and closed composting systems on a laboratory scale. Two open system methods, one aerated windrow and one static pile, and three closed experiments using a compostumbler were performed. Throughout the whole study woodchips (in varying ratios) were used as a bulking agent. An initial moisture content of nearly 60% in the sludge - woodchips mixture produced the highest degree of composting activity over a three week period. Biological drying during the process was indicated by an increase in total solids up to values between 17% and 27%. Partial stabilization of the organic fraction was indicated by a decrease in volatile solids of 28% - 50%. In two closed system trials a total carbon decrease of 26% - 42% was observed, serving as an additional indication that there had been a reduction in organic matter. Total nitrogen losses were substantial in all experiments. Reductions were in the range of 14% - 58% with the highest losses observed in the static pile experiment. Phosphorus was found to be stable with only minor concentration changes observed. Temperature development in the composting material followed the well known pattern, provided that the factors influencing the composting process were close to optimal. Temperatures approaching 70°C in the initial stage of the process were measured. Bacteriological studies indicated, that the final composted product was not free from microbial hazard. In one closed system trial, however, no entero-streptococci were observed, indicating a complete inactivation of these indicator microorganisms. Ongoing development of the composting systems used, including improvements of methodologies employed is necessary in conducting further investigations.