Mercury regulation, fate, transport, transformation, and abatement within cement manufacturing facilities: review

The USEPA's 2010 mercury rule, which would reduce emissions from non-hazardous waste burning cement manufacturing facilities by an estimated 94%, represents a substantial regulatory challenge for the industry. These regulations, based on the performance of facilities that benefit from low concentrations of mercury in their feedstock and fuel inputs (e.g., limestone concentration was less than 25 ppb at each facility), will require non-compliant facilities to develop innovative controls. Control development is difficult because each facility's emissions must be assessed and simple correlation to mercury concentrations in limestone or an assumption of ‘typically observed’ mercury concentrations in inputs are unsupported by available data. Furthermore, atmospheric emissions are highly variable due to an internal control mechanism that captures and loops mercury between the high-temperature kiln and low-temperature raw materials mill. Two models have been reported to predict emissions; however, they have not been benchmarked against data from the internal components that capture mercury and do not distinguish between mercury species, which have different sorption and desorption properties. Control strategies include technologies applied from other industries and technologies developed specifically for cement facilities. Reported technologies, listed from highest to lowest anticipated mercury removal, include purge of collected dust or raw meal, changes in feedstocks and fuels, wet scrubbing, cleaning of mercury enriched dust, dry sorbent injection, and dry and semi-dry scrubbing. The effectiveness of these technologies is limited by an inadequate understanding of sorption, desorption, and mercury species involved in internal loop mercury control. To comply with the mercury rule and to improve current mercury control technologies and practices, research is needed to advance fundamental knowledge regarding mercury species sorption and desorption dynamics on materials within cement facilities.     

Assessing the economic efficiency of bioenergy technologies in climate mitigation and fossil fuel replacement in Austria using a techno-economic approach

The core issues of the Austrian energy policy agenda include reducing greenhouse gas (GHG) emissions and dependence on fossil fuels. Within this study, the costs of GHG mitigation and fossil fuel replacement (abatement costs) of established and upcoming bioenergy technologies for heat, electricity and transport fuel production are assessed. Sensitivity analyses and projections up to 2030 illustrate the effect of dynamic parameters on specific abatement costs.     

Low carbon society scenario analysis of transport sector of an emerging economy—The AIM/Enduse modelling approach

The transport sector of a country is the backbone driving the economy forward. Thailand’s land transport sector is modelled using the AIM/Enduse, which is a recursive dynamic optimization model, based on bottom-up modelling principle. The travel demand is divided into two major categories which are passenger travel and freight travel. The objective of this paper is to analyse the mitigation possible through low carbon society (LCS) measures and emission tax (ET). Two scenario clusters are devised along with the BAU case. The LCS scenario cluster has three designed scenarios which are LCS-L, LCS-M and LCS-H. The emission tax (ET) cluster has four scenarios, where the taxes of 50, 100, 200 and 500 USD/t-CO₂ are implemented. Along with this the marginal abatement costs (MAC) of the counter-measures (CMs) and the co-benefits in terms of energy security, productivity and air pollutant mitigation are also assessed. Results show that LCS scenarios are possible of mitigating up to 1230 Mt-CO₂ cumulatively, from 2010 to 2050. In terms of MACs, new vehicles play a pivotal role, along with hybrid vehicles. The Average Abatement Cost (AAC) assessment shows that the AAC of LCS-H scenario is in the order of 100 USD/t-CO₂. All the LCS and ET scenarios show an enhancement in energy security and also a threefold increase in productivity. There is distinct mitigation in terms of air pollutants from the transport sector as well.     

Provincial carbon intensity abatement potential estimation in China: A PSO–GA-optimized multi-factor environmental learning curve method

This study aims to estimate carbon intensity abatement potential in China at the regional level by proposing a particle swarm optimization–genetic algorithm (PSO–GA) multivariate environmental learning curve estimation method. The model uses two independent variables, namely, per capita gross domestic product (GDP) and the proportion of the tertiary industry in GDP, to construct carbon intensity learning curves (CILCs), i.e., CO₂ emissions per unit of GDP, of 30 provinces in China. Instead of the traditional ordinary least squares (OLS) method, a PSO–GA intelligent optimization algorithm is used to optimize the coefficients of a learning curve. The carbon intensity abatement potentials of the 30 Chinese provinces are estimated via PSO–GA under the business-as-usual scenario. The estimation reveals the following results. (1) For most provinces, the abatement potentials from improving a unit of the proportion of the tertiary industry in GDP are higher than the potentials from raising a unit of per capita GDP. (2) The average potential of the 30 provinces in 2020 will be 37.6% based on the emission's level of 2005. The potentials of Jiangsu, Tianjin, Shandong, Beijing, and Heilongjiang are over 60%. Ningxia is the only province without intensity abatement potential. (3) The total carbon intensity in China weighted by the GDP shares of the 30 provinces will decline by 39.4% in 2020 compared with that in 2005. This intensity cannot achieve the 40%–45% carbon intensity reduction target set by the Chinese government. Additional mitigation policies should be developed to uncover the potentials of Ningxia and Inner Mongolia. In addition, the simulation accuracy of the CILCs optimized by PSO–GA is higher than that of the CILCs optimized by the traditional OLS method.     

Numerical Method to Elucidate Likely Target Positions of Chlorine Removal in Anaerobic Sediments Undergoing Polychlorinated Biphenyl Dechlorination

Polychlorinated biphenyl (PCB) contamination in the United States is predominately from commercially manufactured Aroclor mixtures. These mixtures consist of approximately 150 congeners and are characterized by chlorination level and congener distribution profile, with some congeners maintaining a constant relative abundance across the chlorination levels. Once introduced into the environment, changes in congener profiles occur, in some cases altering the relative abundance of congeners correlated in the commercial Aroclors. The shifts in the relationships of the correlated congener pairs (trackers) are used to quantify the likelihood of natural remediation processes occurring in the anaerobic sediment and to identify positions where chlorine removal is likely. A numerical model for elucidating the most likely chlorine positions was developed, implemented, and tested on Hudson River sediment data. The model results show that flanked chlorines were most likely to have been removed, followed by meta chlorines. These results are consistent with those reported by laboratory investigation of Hudson River sediments. The findings suggest that the model can successfully determine the most likely positions of chlorine removal, even in the absence of a priori knowledge of the sediment contamination (source Aroclors) or the dechlorinating organisms. Thus the model can be applied, even where limited knowledge exists regarding the contamination source and the nature of the biogeochemical reactions affecting the fate of PCBs in a particular sediment system.     

Development of a New Zero-Valent Iron Zeolite Material to Reduce Nitrate without Ammonium Release

Previous studies have revealed that the application of zero-valent iron (ZVI) in reducing nitrate is limited by ammonium production and the requirement for adequate pH control. The current study focused on developing a new material potentially applicable in permeable reactive barriers, which can reduce nitrate without ammonium release under unbuffered pH. The new material, referred to as ZanF, is derived from zeolite modified by Fe(II), followed by borohydride reduction. The pseudo-first-order rate constant (kobs) of ZanF in the early period of nitrate reduction was 10 times higher than that of the ZVI used in this study. However, the kobs of ZanF decreased in the reaction period that followed. Even though both ZVI and ZanF produced ammonium as a product of nitrate reduction, ZanF removed it to below detection limits via adsorption, whereas ZVI did not remove it to any significant extent. ZanF maintained its high reactivity even under an initial pH of 6.2 without buffer. The higher ZanF/solution ratio increased the removal rate of ZanF as well as the removal efficiency.     

Lead Removal from Acidic Solutions by Sorption on Cocoa Shells: Effect of Some Parameters

The objectives of this work were to evaluate the effects of different parameters (Pb concentration, solution pH, Ca/Mg/Na/K salt concentrations) on Pb uptake by cocoa shells and to study the mechanisms of Pb removal in very acidic conditions. Sorption tests were conducted in shaken flasks with synthetic Pb solutions and 15 g/L cocoa shells. A lead uptake value of 161 mmol/kg was measured during the assay with [Pb]i = 3.66?mmol/L in solution at pHi = 2.0 and T = 22°C. Results show that Pb uptake is very similar (14.5–16.0 mmol/kg) for an initial pH between 2.0 and 4.0, but a moderate decrease (10.8 mmol/kg) occurred when the initial pH=1.5 and the [Pb]i = 0.25?mmol/L. High Ca and Mg concentrations (2.35 mol/L) in solution induced a significant decrease in Pb removal by cocoa shells, whereas high K and Na concentrations did not affect Pb uptake by this sorbent. This suggests that Pb uptake by cocoa shells is controlled by ion-exchange reactions with Ca/Mg ions and protons. Finally, chemical tests have shown that carboxyl and amine functional groups play a dominant role in Pb uptake by cocoa shells.     

Influence of COD:N:P Ratio on Nitrogen and Phosphorus Removal in Fixed-Bed Filter

This study examined the effects of COD:N:P ratio on nitrogen and phosphorus removal in a single upflow fixed-bed filter provided with anaerobic, anoxic, and aerobic conditions through effluent and sludge recirculation and diffused air aeration. A high-strength wastewater mainly made of peptone, ammonium chloride, monopotassium phosphate, and sodium bicarbonate with varying COD, N, and P concentrations (COD: 2,500–6,000, N: 25–100, and P: 20–50 mg/L) was used as a substrate feed. Sodium acetate provided about 1,500 mg/L of the wastewater COD while the remainder was provided by glucose and peptone. A series of orthogonal tests using three factors, namely, COD, N, and P concentrations, at three different concentration levels were carried out. The experimental results obtained revealed that phosphorus removal efficiency was affected more by its own concentration than that of COD and N concentrations; while nitrogen removal efficiency was unaffected by different phosphorus concentrations. At a COD:N:P ratio of 300:5:1, both nitrogen and phosphorus were effectively removed using the filter, with removal efficiencies at 87 and 76%, respectively, under volumetric loadings of 0.1?kg?N/m3?d and 0.02?kg?P/m3?d.     

Removal of Endosulfan from Water Using Wood Charcoal—Adsorption and Desorption

Endosulfan, one of the most widely used pesticides in various sectors including agriculture, has been reported posing a threat to the ecology as well as to the environment. Contamination of groundwater and surface water sources with various pesticides is well documented, and this problem is prominent, particularly in rural areas. In the present study, efforts are made to remove endosulfan from water using wood charcoal, a local and low cost adsorbent. It gave removal efficiency of more than 90%. Equilibrium time was found to be around 5?h. Wood charcoal showed an uptake capacity of 0.53?mg/g with initial endosulfan concentration in the range of 0.25–5?mg/L and 1.77?mg/g for the range of 2–50?mg/L. Langmuir isotherm gave a better prediction of adsorption capacity than the Freundlich. The Langmuir isotherm fit also gave a better correlation with the experimental data. In the desorption study carried out, 10% solutions of acetone, methanol, acetic acid, saturated EDTA solution, and distilled water were used as eluents. Ten percent methanol solution was found performing well with an adsorbent regeneration of more than 80% after four cycles of adsorption desorption. Desorption was found to follow a zero order equation in the case of 10% solutions of both acetone and methanol.     

Ozone Generation in Air by a DC-Excited Multi-Pin-to-Plane Plasma Source

In the fields of material processing and environmental technology, atmospheric pressure non-thermal plasmas embrace a broad range of applications. Ozone generation is one of them. This paper discusses a DC-excited atmospheric pressure glow discharge in a multi-pin-to-plane electrode configuration for the production of ozone in air. The influence of discharge current, temperature, flow rate and air humidity is investigated. A simple model is proposed to predict the experimental results for the ozone production and ozone concentrations.