Odour emissions and corrosion concerns can be a constant focus for many wastewater treatment and collection system owners, usually from the first day that their collection systems begin operation. Many sewer systems are reaching the end of their useful life, or have experienced either odour or corrosion issues. This paper shows a link between odour generation and corrosion potential, and how modelling can be used to assist in odour/corrosion assessments of existing wastewater collection systems. A model has been developed that is capable of predicting liquid-phase sulphide generation and subsequent release to overlying sewer headspace as hydrogen sulphide (H2S), where it can be the source of either odour or corrosion problems. This paper presents an overview of the model, and uses a case study involving both odour and corrosion issues to demonstrate the utility in modelling. The model was used to identify potential locations within the system where odour/corrosion may be problematic, as well as assisting in the evaluation of potential odour control alternatives.

This paper provides an overview of the impact of global wanning concerns on wastewater treatment plant design and operation. The issues surrounding global wanning concerns are discussed, along with the linkage between global warming and greenhouse gas emissions. US greenhouse gas emission inventories are reviewed, along with the role of wastewater treatment plants in reducing such emissions. It is found that process related emissions from wastewater treatment plants are less than 1 % of total greenhouse gas emissions. Limited flexibility exists to reduce processrelated emissions. One of the principal options is to minimize Cfu emissions at the expense of CO2 emissions by stabilizing biodegradable organic matter aerobically rather than anaerobically, or by capturing and combusting any CH 4 produced. The global wenning potential of Cfu is 21 times higher than that of C02. Principal options for reducing greenhouse gas emissions involve selection of biosolids reuse options and energy consumption measures. Landfilling of waste biosolids should be avoided as this leads to Cfu emissions. Agricultural reuse can reduce greenhouse gas emissions if land management practices increase soil organic carbon content and/or if crops are grown that can be used to produce renewable fuels (such as ethanol).Greenhouse gas emissions can also be reduced by energy conservation measures that reduce the use of fossil fuels, or the consumption of energy produced from them. Greenhouse gas emissions may be considered during the evaluation of alternatives for upgrading wastewater treatment plants, or as part of an overall emissions inventory.

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The Sacramento Regional Wastewater Treatment Plant (SRWTP) recently evaluated several alternatives to address long-term biosolids dewatering, drying, and handling and disposal issues. SRWTP decided to evaluate air quality emissions and impacts including permitting requirements, criteria pollutants, greenhouse gases, hazardous air pollutants (HAPS), controlled emissions, and air emissions from hauling trucks and secondary sources that are related to biosolids treatment (e.g., boilers or furnaces for heat drying, fugitive emissions from storage tanks, etc.). This paper provides a full picture of total air quality impacts from biosolids treatment and direct insights into any air quality permitting concerns under current Sacramento Metro Air Quality Management District (SMAQMD) and U.S. Environmental Protection Agency (EPA) air quality laws and regulations.Air emission totals for each biosolids treatment alternative included air emissions from secondary sources, controlled sources, and truck hauling. Air emissions from the following biosolids treatment alternatives were evaluated:• Centrifuge dewatering emissions • Plate and frame press dewatering emissions • Indirect drying emissions -including dewatering and secondary emissions • Direct drying emissions -including dewatering and secondary emissions • Controlled emissions -odor control, impingement plate scrubber, regenerative thermal oxidizer (RTO) • Trucking emissions for each alternative All air emissions from the biosolids treatment alternatives and their associated regulatory impacts were insignificant. No problems were predicted in attaining air district permits or significantly impacting the environment. Emissions from dewatering with no drying, were much lower than any of the drying alternatives (with trucking emissions included). The overall emissions for the combined dewatering, drying, and trucking alternatives presented minimal environmental impacts and should therefore readily receive permits. It should be noted, however, that other non-air quality factors such as odors, cost effectiveness, reliability, and ease of operation may have a strong influence on which alternative is selected.

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