Fate of emerging contaminants in an advanced SBR wastewater treatment and reuse facility incorporating UF, RO, and UV processes.

A critical factor for widescale water reuse adoption is the capability of advanced wastewater treatment facilities to consistently produce high-quality water by efficiently removing various pollutants, including emerging contaminants (ECs). This study monitored the fate of seventeen ECs (which included pesticides, antibiotics and other pharmaceutically active compounds) over six months in an advanced wastewater reuse facility situated in the United Arab Emirates. The facility integrates a sequencing batch reactor (SBR) based sewage treatment plant (STP) with a water recycling facility featuring ultrafiltration (UF), reverse osmosis (RO), and ultraviolet (UV) disinfection. ECs were detected and quantified at the influent and effluents of the various treatment stages, using an ultra-high-performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS). The STP exhibited variable removal efficiencies, achieving >90 % removal for compounds like caffeine and acetaminophen, while others, such as carbamazepine and thiabendazole, displayed poor removal (<10 %). UF treatment broadly resulted in limited removal, with ECs in permeate typically persisting in the 1-10 ng/L range. Subsequently, after undergoing RO treatment, eight ECs were still detected in the RO permeate, albeit at <1 ng/L, except for imidacloprid (2.5 ng/L). Conversely, the final UV disinfection step led to concentration increases of certain ECs, namely imidacloprid, thiabendazole, sulfamethoxazole, sulfamethazine and caffeine. Overall, the total EC concentration levels decreased considerably from 2300 ng/L in the STP influent to 5.2 ng/L in the RO permeate. However, a subsequent increase to 27.5 ng/L was observed after UV disinfection. While the study underscores the effectiveness of advanced treatment processes, notably RO, in reducing EC concentrations, it also demonstrates the importance of continuous EC monitoring in such facilities as many compounds persist post treatment. Additionally, the potential for processes like UV disinfection to increase certain EC concentrations highlights the need to optimize treatment trains to minimize EC concentration rebound.

Development of a dynamic optimization framework for waste management systems.

Waste to energy (WTE) technologies have emerged as an alternative solution to municipal solid waste management. WTE systems provide major environmental and economic benefits by converting waste into accessible energy, as part of an integrated solid waste management (ISWM) strategy. However, previous studies showed that establishing an ISWM strategy based on a single type of WTE systems does not necessarily realize maximum benefits. Hence, optimizing the selection of WTE systems as part of a hybrid waste management strategy can potentially achieve maximum benefits and minimize negative impacts. However, such task is challenging due to the various alternatives and objectives, particularly those related to the material and energy recovery systems. This article presents the methods used to develop a systematic optimization framework that identifies the most beneficial set of ISWM systems through mathematical modelling. The methods include the procedures of the established framework, including base model computations, as well as the comprehensive modelling and optimization methods.•The energy recovery, carbon footprint, and financial profitability are computed for selected WTE facilities.•The multi-objective mathematical programming is solved using the weighted comprehensive criterion method (WCCM).•The model is implemented in CPLEX software using mathematical programming language (OPL).

Mechanistic-empirical evaluation of specific polymer-modified asphalt binders effect on the rheological performance.

Major distresses such as rutting, fatigue, and thermal cracking are facing asphalt pavement structures due to continuous heavy traffic loading and climate change. The modification of asphalt binders (one of the main components of the asphalt paving mix) has the potential to mitigate distresses through using different additives. Polymer modified asphalt (PMA) binders showed a noticeable resistance to pavement distresses as reported in previous studies. The present study aims to evaluate the effect of polymer modification on the rheological properties of asphalt binders through laboratory tests. The polymers included styrene-butadiene-styrene (SBS) and epolene emulsifiable (EE2) types. The 60/70 binder was used as a control for comparison. The Mechanistic-Empirical Pavement Design Guide (MEPDG) was also utilized to simulate the effect of PMA binders on the rheological properties under different climatic conditions and structural capacities. Additionally, the MEPDG was further utilized to compare the effect of asphalt binders on rheological properties using four different binder input levels. Findings of the study showed that laboratory tests experienced varying outcomes regarding the most efficient asphalt binder by means of distresses resistance. However, the MEPDG evaluation showed that the overall ranking of asphalt binders positively impacting the rheological properties was as following: (1) 4.5% EE2 PMA, (2) 4% EE2 PMA, (3) 60/70 binder, (4) 5% SBS PMA, and (5) 4% SBS PMA binders. Furthermore, statistical analysis illustrated that the effect of using different binder input levels on the performance of pavement varied relatively to the evaluated distresses. The analysis showed that using different binder input levels would affect, to a certain extent, the asphalt binder influence on rheological properties only when evaluating rutting and fatigue distresses. Therefore, it is recommended that precise asphalt binder inputs, that is, shear complex modulus (G*) and phase angle (δ) are used when designing pavement structures in regions with hot and mild climate conditions.

Waste to energy potential in middle income countries of MENA region based on multi-scenario analysis for Kafr El-Sheikh Governorate, Egypt.

The environmental risks of traditional waste disposal methods, together with the resource and energy value of waste, had established the foundation for waste-to-energy (WTE) technologies. WTE is rarely implemented in developing countries, mostly due to the lack of knowledge and experience under their specific local conditions. The present research investigates the feasibility of WTE strategies in middle income developing countries of the Middle East and North Africa (MENA) region. Multiple waste management scenarios, involving incineration and anaerobic digestion, were evaluated based on energy, economic, and environmental parameters. A multi-criteria assessment was conducted for the Governorate of Kafr El-Sheikh (Egypt); a 3.2-million rural-urban agro-industrial population with socio-economic and demographic features similar to those of the selected MENA countries. The actual waste generation rates and characteristics of Kafr El-Sheikh were measured through a comprehensive field study. It was found that anaerobic digestion with recycling is the optimum strategy for Kafr El-Sheikh, with annual energy potential of 1170-kWh per ton of waste and net economic savings of 6.5 million USD. This optimum waste management scenario was extended to the selected MENA countries to investigate potential benefits of shifting to WTE-based waste management strategies. The total annual energy production was estimated to be 103,000-GWh, which translates to 17% of the total energy consumption. Moreover, greenhouse gas emissions were reduced by around 98,500-Gg CO2 annually, which represents around 6.5% of the total annual CO2 footprint generated by the selected countries. Furthermore, the overall economic benefits ranged between -12 and 200 million USD for the selected countries.

Financial feasibility of waste to energy strategies in the United Arab Emirates.

The present research explores the financial feasibility of alternative waste management strategies, based on waste to energy, in the United Arab Emirates. The integrated strategies assessed in this study were primarily based on anaerobic digestion (AD) or incineration. The economics of both strategies were evaluated based on various revenue and cost streams, as well as multiple financial parameters over a 20-year period. Carbon credits were estimated based on the projected carbon emission reductions from each strategy. Realistic public participation and recovery rates for waste separation and recycling were applied. It was found that the incineration strategy is profitable with a net present value of 181 million USD, compared to -127 million USD for the AD strategy. The incineration strategy was more financially favorable in terms of the payback period, internal rate of return and profitability index, mainly due to the larger amount of processed waste. On the other hand, the AD was substantially affected by the landfilling cost of the produced digestate as well as the low participation rate in the proposed food waste separation program. The levelized cost of electricity for incineration and AD was 0.096 and 0.101 USD/kWh, respectively. The incineration and AD strategies were found to breakeven at a minimum of 52.4 and 31.2 million tons of processed waste, respectively. Certain legislative and social modifications made the AD strategy financially feasible. The sensitivity analysis showed that the net present values of both strategies were strongly affected by the variations in capital investments, landfilling costs, and electricity tariff.