Alternatives To Active HVAC Systems

ABSTRACT Sustainable and effective treatment of landfill leachate has become one of the most important environmental problems due to the fluctuating composition and quantity, as well as its high concentrations of pollutants. High-tech solutions applied for the leachate treatment are expensive and energy consuming, and in addition they are not suitable at many landfill sites, especially those in rural areas. Hence there is need to develop novel and sustainable low-energy systems for the effective treatment of landfill leachates. Constructed wetlands (CWs) are inexpensive simple to operate and they have the potential to remove not only organic carbon and nitrogen compounds, but heavy metals. This study focussed on the design, development and experimental investigation of a novel CWs for the treatment of landfill leachate. The CWs employed dewatered ferric waterworks sludge (DFWS) as the main substrate. The overall aim of the study was to design and assess the novel configuration of the CWs, whilst also contributing to advancing the understanding of pollutant removal from the landfill leachate in the CWs, through the development of models to explain the internal processes and predict performance. The key design and operational variables investigated were: the primary media used, i.e. the DFWS, and the wetting and drying regimes. The CWs was configured as 4- stages in series which was operated for 220 days. Thereafter, an additional unit was added due to clogging and the CWs was operated for 185 days in this second period. Results and experimental observations indicate that the chemical treatment processes (adsorption and precipitation) contributed to the clogging. The DFWS used served as adsorbent for heavy metals removal in the system. Results of heavy metals, organic matter (COD), ammonia and total nitrogen removal indicate average removals of 99%, 62%, 83% and 81%, respectively in first period; and 100%, 86%, 90% and 82% in second period, with an average heavy metals loading rate 0.76 g m-2 day-1 , organic loading rate 1070 g m-2 day-1 , ammonia loading rate of 178 g m-2 day-1 and total nitrogen loading rate 192 g m-2 day-1 . Results were supported through mathematical analysis using STELLA model for heavy metals transformation in CWs and numerical modelling using HYDRUS CW2D, which enhanced understanding of the internal processes for organic matter and nitrogen 3removal. The result from STELLA modelling showed that up to 90% of the removal of heavy metals was through adsorption, which is highly significant. While HYDRUS CW2D results showed that the main path of nitrogen removal was through simultaneous nitrification and denitrification. Overall, results have shown that CWs design has great potential for reduction of metals and nutrients in landfill leachate. Results of this study can contribute to future CW research and design for landfill leachate treatment, through the increased understanding of long-term pollutant removal in these systems. In time, this may result in the wider application of CWs for landfill leachate treatment to better protect the environment.

Introduction: This manual provides guidance and criteria for the design of small water supply, treatment, and distribution systems. For the purpose of this manual, small water systems shall be those having average daily design flow rates of 380 000 liters per day (l/d) (100 000 gallons per day (gpd)) or less. However, the use of the term small is arbitrary, there being no consensus in the water supply literature with respect to its meaning. Regulations regarding the acceptability of a water source, degree of treatment required, and the monitoring requirements are not based on flow rates, but rather on a water system classification relating to the number of people served and for what period of time. Figure 1-1 provides a flowchart for system classification. Refer to Chapter 3, paragraph 3-4b for the appropriate nomenclature.

Introduction • The same holds true for industrial equipment/system. • Maintenance is one of the most indispensable job in any industrial organization.

PROCESS ENGINEERING AND THE ROLE OF PROCESS ENGINEER   Process design is the design of processes for desired physical and or chemical transformation of materials. Process design is central to chemical engineering and it can be considered to be the summit of chemical engineering, bringing together all of the components of that field. Process Engineering involves the design of unit operations & equipment design. Role of Process Engineer: Chemical engineers (or process engineers) are responsible for developing new industrial processes and designing new process plants and equipment or modifying existing ones. The processes that they come up with are used to create products ranging from oil and gas, chemicals, petrochemicals, and specialty chemicals to food and drink. It is a vocation wherein the process engineer is supposed to perform any one or all of the activities mentioned below to provide documentation for a safe, reliable, and profitable design  Design new equipment/unit/plant as per good and internationally accepted engineering practices (Greenfield)  Rate or checks the adequacy of existing equipment/unit/plant for changed operating conditions (e.g. pressure, temperature, flow, etc.) as per good and internationally accepted engineering practices (Brownfield) 

Abstract Aerobic granular sludge (AGS) comprises an aggregation of microbial cells in a tridimen sional matrix, which is able to remove carbon, nitrogen and phosphorous as well as other pollutants in a single bioreactor under the same operational conditions. During the past decades, the feasibility of implementing AGS in wastewater treatment plants (WWTPs) for treating sewage using fundament tally sequential batch reactors (SBRs) has been studied. However, granular sludge technology using SBRs has several disadvantages. For instance, it can present certain drawbacks for the treatment of high flow rates; furthermore, the quantity of retained biomass is limited by volume exchange. Therefore, the development of continuous flow reactors (CFRs) has come to be regarded as a more competitive option. This is why numerous investigations have been undertaken in recent years in search of different designs of CFR systems that would enable the effective treatment of urban and industrial wastewater, keeping the stability of granular biomass. However, despite these efforts, satisfactory results have yet to be achieved. Consequently, it remains necessary to carry out new technical approaches that would provide more effective and efficient AGS-CFR systems. In particular, it is imperative to develop continuous flow granular systems that can both retain granular biomass and efficiently treat wastewater, obviously with low construction, maintenance and exploitation cost. In this review, we collect the most recent information on different technological approaches aimed at establishing AGS-CFR systems, making possible their upscaling to real plant conditions. We discuss the advantages and disadvantages of these proposals and suggest future trends in the application of aerobic granular systems. Accordingly, we analyze the most significant technical and biological implications of this innovative technology.