Assessment and optimization of environmental systems using data analysis and simulation.

For most environmental systems, specifically wastewater treatment plants and aquifers, a significant number of performance data variables are attained on a time series basis. Due to the interconnectedness of the variables, it is often difficult to assess over-arching trends and quantify temporal operational performance. The objective of this research study was to provide an effective means for comprehensive temporal evaluation of environmental systems. The proposed methodology used several multivariate data analyses and statistical techniques to present an assessment framework for the water quality monitoring programs as well as optimization of treatment plants and aquifer systems. The developed procedure considered the combination of statistical and data analysis algorithms including correlation techniques, factor analysis and principal component analysis, and multivariate stepwise regression analysis. Those methodologies were used to develop a series of independent indexes to quantify the composition of wastewater and groundwater. Also, by developing a stepwise data analysis approach, a baseline was introduced to discover the key operational parameters which significantly affect the performance of environmental systems. Moreover, a comprehensive approach was introduced to develop numerical models for forecasting key operational and quality parameters which can be used for future simulation and scenario analysis practices. The developed methodology and frameworks were successfully applied to four case studies which include three wastewater treatment plants and an aquifer system. In the first case study, the aforementioned approach was applied to the Floyds Fork water quality treatment center in Louisville, KY. The objective of this case study was to establish simple and reliable predictive models to correlate target variables with specific measured parameters. The study presented a multivariate statistical and data analyses of the wastewater physicochemical parameters to provide a baseline for temporal assessment of the treatment plant. Fifteen quality and quantity parameters were analyzed using data recorded from 2010 to 2016. To determine the overall quality condition of raw and treated wastewater, a Wastewater Quality Index (WWQI) was developed. To identify treatment process performance, the interdependencies between the variables were determined by using Principal Component Analysis (PCA). The five extracted components adequately represented the organic, nutrient, oxygen demanding, and ion activity loadings of influent and effluent streams. The study also utilized the model to predict quality parameters such as Biological Oxygen Demand (BOD), Total Phosphorus (TP), and WWQI. High accuracies ranging from 71% to 97% were achieved for fitting the models with the training dataset and relative prediction percentage errors less than 9% were achieved for the testing dataset. The presented techniques and procedures in this case study provide an assessment framework for the wastewater treatment monitoring programs. The second case study focused on assessing methane production of a novel combined system for treatment of high strength organic wastewater. The studied pilot plant comprised Rotating Biological Contactor (RBC) process under anaerobic condition, in conjunction with Moving Bed Biofilm Reactor (MBBR) as the combining aerobic process. Various operational parameters were tested to maximize the Chemical Oxygen Demand (COD) removal performance and methane gas production from treating high strength synthetic wastewater. The identified optimal parameters included hydraulic retention time, organic loading rate, and disk rotational speed; equal to 5 days, 7 rpm, and 2 kg COD/m3/d, respectively. Under these conditions, the combined system achieved high removal efficiency (98% from influent COD of 10,000 mg/L) with additional benefit of methane production (116.60 L/d from a 46-liter AnRBC reactor). The obtained results from conducting this case study confirmed the effectiveness of integrated hybrid system in achieving both high removal efficiency and methane production. Thus, this system was recommended for treating high strength organic wastewater. The third case study focused on assessing the feasibility of using a contact stabilization process for secondary treatment of refinery wastewater through a step by step analysis. the studied pilot plant comprised contact-stabilization activated sludge process in conjunction with clarification reactor. Various operational parameters were tested to minimize excessive sludge production and maximize system removal performance from treating petroleum refinery wastewater. The mixed liquor dissolved oxygen (DO) and the rate of activated return sludge (RS) were selected as key operational parameters. The results indicated that the system had an optimum performance under applied aeration of 3.7 mg oxygen per liter of mixed liquor and 46% return sludge. This operational combination resulted in COD removal efficiency of 78% with daily biomass production of 1.42 kg/day. Considering the results from this case study, the contact stabilization activated sludge process was suggested as an effective alternative for secondary treatment of wastewater from petroleum refineries. The last case study combined probabilistic and deterministic approaches for assessing aquifer’s water quality. The probabilistic approach used multivariate statistical analysis to classify the groundwater’s physiochemical characteristics. Building upon the obtained results, the deterministic approach used hydrochemistry analyses for a more comprehensive assessment of groundwater suitability for different applications. For this purpose, a large geologic basin, under arid weather conditions, was evaluated. The ultimate objective was to identify: 1) groundwater classification scheme, 2) processes governing the groundwater chemistry, 3) hydrochemical characteristics of groundwater, and 4) suitability of the groundwater for drinking and agricultural purposes. Considering the results from multivariate statistical analysis, chloride salts dissolution was identified within the aquifer. Further application of the deterministic approach revealed degradation of groundwater quality throughout the basin, possibly due to the saltwater intrusion. By developing the water quality index and a multi-hazard risk assessment methodology, the suitability of groundwater for human consumption and irrigation purposes were assessed. The combined consideration of deterministic and probabilistic approaches provided an effective means for comprehensive evaluation of groundwater quality across different aquifers or within one. The presented procedures and methodologies in this research study provide environmental analysts and governmental decision makers with a comprehensive tool to evaluate current and future quality conditions within any given wastewater treatment plants and/or aquifer systems

Environmental economic impact assessment in China: Problems and prospects

The use of economic valuation methods to assess environmental impacts of projects and policies has grown considerably in recent years. However, environmental valuation appears to have developed independently of regulations and practice of environmental impact assessment (EIA), despite its potential benefits to the EIA process. Environmental valuation may be useful in judging significance of impacts, determining mitigation level, comparing alternatives and generally enabling a more objective analysis of tradeoffs. In China, laws and regulations require the use of environmental valuation in EIA, but current practice lags far behind. This paper assesses the problems and prospects of introducing environmental valuation into the EIA process in China. We conduct four case studies of environmental economic impact assessment (EEIA), three of which are based on environmental impact statements of construction projects (a power plant, a wastewater treatment plant and a road construction project) and one for a regional pollution problem (wastewater irrigation). The paper demonstrates the potential usefulness of environmental valuation but also discusses several challenges to the introduction and wider use of EEIA, many of which are likely to be of relevance far beyond the Chinese context. The paper closes with suggesting some initial core elements of an EEIA guidelineEnvironmental impact assessment; Environmental valuation; China; Economic analysis

Assessing the Role of Magnetite in Municipal Wastewater Treatment

Some municipal wastewater treatment (MWWT) facilities have adopted magnetite in their treatment processes through a technology called BioMag® to meet effluent regulatory requirements for total nitrogen and total phosphorus. However, there is limited information on the mechanisms and efficiency of magnetite in the removal of nitrogen (N) and phosphorus (P) from wastewater. This research, therefore, estimated its effectiveness in the removal of these nutrients, with a case study of the Marlay-Taylor Water Reclamation Facility in Maryland. The intervention analysis model was used, but a new forecasting approach to the model was proposed to fit the data in this study and other similar data. Results showed a significant improvement in both N and P removal. Graphical analyses showed an improvement in operating parameters like the mixed liquor suspended solids and sludge volume index. An account of the N and P removal mechanisms by the magnetite was also provided.Some MWWT facilities using magnetite in their treatment process stabilize their waste sludge using anaerobic digestion (AD) and produce biogas. Therefore, laboratory studies were conducted to determine the effect of magnetite on biogas production (mainly methane and carbon dioxide) and on hydrogen sulfide (H2S) gas reduction. Results showed no significant differences in biogas production, contrary to some studies which reported increases in methane yield with magnetite addition. H2S in the biogas reduced below the concentration that is immediately dangerous to life and health (IDLH). An increase in dissolved iron was also noted. Some recent studies that used magnetite and other conductive materials in AD experiments reported elemental sulfur (So) formation in the digesters. However, previous research that used iron compounds reported iron sulfide (FeS) formation as the mechanism of H2S reduction. Therefore, a bioenergetics model was used to determine if the oxidation of H2S to So is theoretically possible in the AD environment. So formation could also occur due to air presence or leakage in the digesters. Results showed that the reaction leading to So formation was exothermic, implying that energy was produced which could support microbial growth. However, conductive material may be required to initiate this reaction by facilitating electron transfer

Wastewater irrigation and health: assessing and mitigating risk in low-income countries

Wastewater irrigation / Public health / Health hazards / Risk assessment / Epidemiology / Sewage sludge / Excreta / Diseases / Vegetables / Leaf vegetables / Economic impact / Wastewater treatment / Irrigation methods / Developing countries

Urban wastewater reuse for crop production in the water-short Guanajuato River Basin, Mexico

Water quality / Waste waters / Water reuse / Water resource management / River basins / Irrigation water / Crop production / Water use / Data collection / Case studies / Mexico / Guanajuato River Basin / Tula Irrigation District

Long-term phosphorus removal in land treatment systems: Evaluation, experiences, and opportunities

Excessive release of phosphorus (P) from urban wastewater into water bodies is a significant environmental concern. Land treatment systems (LTS) have been used for the last 150 years as a low-cost and low-energy tertiary wastewater treatment. However, their P removal capacity is limited by soil adsorption capacity. Accurate P-removal lifespan prediction is needed to provide confidence in this technology and to support long-term wastewater treatment planning. This review outlines the history of LTS, describes the main P removal processes in soils, and critically analyzes the research methods used to date to assess long-term P removal in soil. Finally, an assessment is made of the role that modeling tools can play in aiding our understanding of P processes in LTS soils and in forecasting system longevity

Costructed Wetlands. A biological alternative wastewater treatments and its role in the new circular economy

The climate changes, the natural resources depletion, the population number increase are alarm bells for the future that must push the humanity to turn on more sustainable use of the natural resources, particularly the water. The water management must shift towards solutions acted to protect, safeguard, and sustainably use the available water resources. A new water scheme must be implemented, in which the waste paradigm must be overtaken and substituted with resource-oriented one. The Thesis aims to present the Constructed Wetland (CW) technology, an attractive green solution for wastewater treatment that nowadays is consolidated as a efficient and valid Natural Based alternative to the conventional systems. The different typologies of CWs are exposed as well as their advantages, disadvantages, and applications. The removal pollutant processes (biological, physical, and chemical processes) occurred within, are deeply analysed and the choice of the suitable vegetation species depending on the wastewater characteristic discussed. Furthermore, I give a brief overview on the European and Italian regulations before explaining in details the design (preliminary and empirical) methods. The treatment goodness and effectiveness are discussed and commented with helping of working applications. Finally, the future role of the CWs systems in circular economy approach is clarified and an overview on the water management scheme modification (from waste paradigm to resource-oriented concept) is provided. The potential applications of CWs within this new scheme are outlined and an in-depth study on recreative applications of CW (Natural Swimming Pools technology) are presented