bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Well Test Interpretations to Constrain the Small Scale Petrophysical Anisotropy (kv/kh)
Authors: Wigniolle Eric , Massonnat Gerard
Published: September 2013

A recurrent issue when performing an up-scaling workflow is to assign representative values for the small scale petrophysical anisotropy ratio kV/kH. Most of the time the data provided by the plugs is not appropriate due to the absence of vertical sampling or to problems of representativeness. Where plug data is available kV/kH ratios are often found to be close to one, a value too high to be realistic when considering geological heterogeneity at small scale.

A methodology is proposed in order to give more appropriate ranges of values for the small scale permeability anisotropy ratio (kV/kH) as an input during the up-scaling workflow. When a well test with partial penetration interpretation is available, it is possible to use the large scale anisotropy ratio Kv/Kh obtained from spherical flow equations and thus constrain the small scale anisotropy ratio kV/kH.

The approach consists in: 1) building a fine scale grid whose size is consistent with the well test investigation radius, 2) populating the grid with facies and petrophysical characteristics observed at the well, and 3) up-scaling the fine scale grid so as to compare the upscaled anisotropy ratio Kv/Kh with the one derived from the well test interpretation.

The method was successfully tested on different field cases in turbidite and carbonate environments. Reference values of kV/kH ratios associated to facies have been determined and can be used, as an initial starting point during the up-scaling process. Guide lines for matching the parameters are also provided.
Thin Beds And Cut-Offs: A Probabilistic Approach For An Improved Assessment And Modelling Of The Net Porous Volume
Authors: Clavel J. , Ruelland P.
Published: September 2013

The objective of the work was to improve the knowledge and understanding of sedimentary facies which consist of thin beds, the impact of the cut-offs, and to improve the coherency and quality of 3D models.

Applying a cut-off consists in defining a threshold value on one or more logs to separate the reservoir intervals in which hydrocarbons are mobile from the gross rock thickness. In a thin beds context, this deterministic approach is insufficient because of the resolution of the logs and a limited number of data. The probabilistic approach considers that the relationship between the cut-off value on the selected log and hydrocarbon mobility in the sandy laminae is a statistical function.

The method is adapted to alternating sand-shale thin beds that have not undergone extensive burial, and has been applied to reservoirs in a turbidite depositional context. In such environment, the cut-off on the VClay log is the most discriminating.

The process of upscaling petrophysical properties is performed for each facies using two cellular mini-models. One is built at log resolution; the second at the scale of the cells in the reservoir model. The cut-off is applied in the log-scale mini-model using a probability function on VClay. The upscaling process provides distributions and correlation transforms for PHIE, NTG and PHIEnet which can be then used to populate the reservoir model. Transforms and Mean values differ from those obtained using a deterministic cut-off as the latter tends to underestimate the reservoir volume in shale-dominated thin bed facies and overestimate reservoir volume in sand-dominated thin bed facies.
Geostatistical Modeling with Seismic Characterization of Wara/Burgan sands, Minagish Field, West Kuwait
Authors: Al-Anezi K. , Kumar S. , Ebaid A. , Bonnel A. , Lucet N. , Lecante G. , Ortet S.
Published: September 2013

The Minagish field covers an area of 90 km2, located in south-western part of Kuwait in onshore position. The studied Cretaceous Wara and Upper Burgan reservoirs, deposited in fluvio deltaic environment (clastic rocks), consist of vertically stacked sands with extensive lateral facies variation. Lower Burgan sands are more significant and blocky in nature with little variations in their properties. Reservoirs geometry, their heterogeneities and structural setting are the key issues for the development of the reservoirs.

The geostatistical methodology used to simulate a high-resolution geological model representative of the reservoir heterogeneity will be described in this paper. The paper will particularly discuss the techniques used for the integration of seismic attributes to constrain the facies modeling, as well as a nested simulation workflow for a realistic representation of heterogeneities.

The three dimensional structural grid was classically based on the seismic interpretation (faults and horizons) and the well correlations. Facies simulation was performed using PluriGaussian functions approach in a non-stationary frame based on vertical proportion curves (VPC) matrix. The distribution has been done separately in three zones: Wara, Upper Burgan and Lower Burgan. For Wara and Upper Burgan zones, nested simulations were used. The lithology (sand or shale) was simulated in a first step, under the constraint of proportion facies maps extracted from seismic data. In a second step, the depositional environment facies were simulated in the sand lithology. These simulations were based on two Gaussian functions to better integrate the various orientations of the different deposits, and their complex spatial relationship. For the Lower Burgan zone, because of the very low variability of the sand proportion, a stationary facies simulation was run, using a truncated Gaussian algorithm.

Eventually, the paper underlines the capacity of the PluriGaussian Simulation approach to realistically mimic sedimentary bodies, and to easily incorporate seismic derived information.
Combining Unstructured Grids, Discrete Fracture Representation and Dual-Porosity Models for Improved Simulation of Naturally Fractured Reservoirs
Authors: Maier Christine , Geiger Sebastian
Published: September 2013

Commonly, dual-porosity and dual-permeability models are employed to simulate naturally fractured reservoirs (NFR). Recently, dual-porosity models have been extended to include more than one transfer function per simulation grid block. These so-called multi-rate dual-porosity models (MRDP) hence allow for more than one set of rock and fluid parameters to be present within one grid cell, which captures the natural variability in fracture, matrix, and fluid properties more accurately. Discrete fracture and matrix (DFM) based simulators have recently emerged as an alternative in NFR simulation. They use unstructured meshes to model large-scale fractures, fracture corridors, and faults explicitly but cannot represent small-scale fractures because field-simulations would become intractable, even with parallelisation.

In this paper we demonstrate a combined MRDP-DFM approach for the first time. We demonstrate how the MRDP-DFM approach can be discretised using unstructured (tetrahedral) meshes. This facilitates the partition of the geological model into regions where (1) large-scale heterogeneities such are fracture corridors are modelled by the DFM method with appropriately upscaled single-porosity properties and (2) the flow through small-scale fractures is modelled using MRDP method with a distribution of transfer function and effective fracture permeability tensors coming from classical Discrete Fracture Network models.

We use a suite of proof-of-concept simulations to demonstrate that our MRDP-DFM approach yields more realistic forecasts of oil recovery due to gravity drainage and imbibition in fractured reservoirs because it allows us to represent the multi-scale heterogeneities inherent to NFRs more realistically. It hence predicts recovery processes more accurately compared to standard dual-porosity models and more efficiently compared to standard DFM models.
Multi-Objectives Constrained Waterflood Optimization in Tight Carbonates
Authors: Khan H. , Saputelli L. , Carvajal G. A. , Ranjan P. , Wang F. , Knabe S.
Published: September 2013

Production from low permeability carbonate reservoirs is commonly supported by the waterflood (WF) process. Despite decades of research and field experience, oil recovery expectations in carbonates typically remain low due to factors such as high permeability streaks, poor microscopic sweep efficiency, and low mobility ratios, all of which can dramatically impair oil recoveries. Vast amounts of remaining oil-in-place have led operators to analyze opportunities to improve WF management and production.

This paper presents an approach to increase recovery and improve performance indicators in a low permeability carbonate reservoir. The main objective of this effort is to maximize short-term oil rates and long-term recovery while honoring target constraints on voidage-replacement ratio (VRR), reservoir pressure, sweep efficiencies, and production and injection rates. In essence, our approach seeks optimum WF solutions by coupling a full-field reservoir simulator with an adaptive, simulated annealing optimization engine.

Predefined scenarios impose hard constraints on production and injection rates, field conditions, and well operating constraints. Voidage replacement ratios (VRR) and nominal pressure (Pn), volumetric sweep efficiency (Evol) and displacement efficiency (Ed) are soft constraints used to calculate design feasibility. Reservoir recovery and displacement efficiency performance indicators are pursued at different levels in the optimization loop. The outcome is that the following month's operational decisions are suggested by the optimizer. This paper describes how this optimization methodology provides improvements in short-term production rates of about 10–20% while enhancing oil recovery between 1–8%. This paper also discusses additional strategies to further improve oil recovery expectations using this automated workflow as the foundation.
Optimized Modeling Workflows for Designing Passive Flow Control Devices in Horizontal Wells
Authors: Gurses Sule , Vasper Adam
Published: September 2013

The benefits of horizontal wells from both a production and reservoir characterization perspective are well known1,2,3. With the benefits however come several challenges, usually concerning uneven production or injection profiles. Interval Control Device (ICD) completions have become popular as a method of addressing these problems controlling fluid flow between the reservoir and wellbore or vice versa in horizontal wells4,5,6. Most ICD devices are passive or fixed once installed downhole, making the design process of these completions very important.

This paper describes the elements of the design for ICD completions and workflows that integrate them within an easy to use software environment. The objectives of the completion are discussed and how to deal with potentially contradictory requirements. The advantages of using 3-D reservoir simulation versus static modeling are listed and workflows making 3-D dynamic methods faster and more accessible explained. The most common ICD design strategies are associated with the reservoir challenges they can address and the quality of the data required. Workflows are introduced for building fit-for-purpose simulation models depending on the data and time availability, and the reservoir challenges being faced. Finally, optimizers are discussed as an aid to ICD completion design.
Effect of Rock and Wettability Heterogeneity on the Efficiency of WAG Flooding in Carbonate Reservoirs
Authors: Ahmed Elfeel M. O. , Al-Dhahli A. , Jiang Z. , Geiger S. , van Dijke M. I.
Published: September 2013

Carbonate reservoirs contain more than half of the world's remaining petroleum reserves and are increasingly becoming targets for water-alternating-gas (WAG) flooding as secondary or tertiary recovery. Heterogeneity in carbonate reservoirs spans from pore- to reservoir-scale. This is exacerbated by the presence of natural fractures and post-depositional dissolution. Furthermore, carbonate reservoirs tend to have variable wettability that impacts fluid flow which adds to reservoir uncertainty and renders managing WAG floods difficult.

In this work, we examine the effect of rock and wettability heterogeneity on recovery profiles in naturally fractured carbonate reservoirs (NFCR). To simulate WAG flooding in NFCR with arbitrary wettability, we use saturation functions derived from a state-of-the-art pore network model to preserve multi-scale heterogeneities at the pore-scale. We study the interplay of capillary, gravity and viscous forces at an intermediate scale, then simulate WAG flooding in the presence of fractures in a heterogeneous carbonate ramp outcrop model.

Adding the permeability and wettability heterogeneities impacts ultimate recoveries during water injection cycles by up to 6% and 14% absolute, respectively. Both heterogeneities affect the speed of recovery during gas injection cycles. Depending on its relation to permeability distribution, non-uniform wettability of matrix blocks can have a substantial impact on recovery during water injection cycles while recovery efficiency during the gas injection cycle can be reduced by a factor of 50%.

Our work identifies the key factors that must be considered when modelling WAG floods in NFCR. We evaluate the reliability of conventional dual-porosity/dual-permeability numerical simulation approaches for NFCR by comparing results with multistage upscaled models through which we capture the fundamental controls on multi-phase flow. Hence, we can offer explanations for possible NFCR responses to WAG flooding and novel ways to improve the predictive ability of field-scale numerical simulation models.
Parallel Adaptive Mesh Refinement for Capturing Front Displacements: Application to Thermal EOR Processes
Authors: Mesri Youssef , Gratien Jean Marc , Ricois Olivier , Gayno Raphael
Published: September 2013

This paper presents a parallel adaptive mesh refinement scheme, that allows the achievement of an optimal accuracy by using dynamic mesh adaptation. The mesh refinement is close to the high error of temperature field. Periodic adaptive refinement is performed such as the refined zones describe accurately the temperature front displacement. This is based on the definition of an error estimator and the search of the optimal mesh that minimizes the error estimator under the constraint of a given number of cells.

The main bottleneck of adaptive mesh refinement in a parallel context is the load unbalance between processes due to refinement around local physical phenomena. This paper presents also, a parallel mesh adaptation algorithm able to deal with partitioned and distributed meshes. Unbalance detection is also taken into account by using a load balancing algorithm capable to improve effectively the performance of the simulation. All AMR algorithms are integrated as a part of Arcane [4], a IFPEN-CEA parallel object oriented framework. Application of this dynamic meshing approach in simulation models with steam injection demonstrates that efficient dynamic meshing can be implemented in a general purpose simulator to provide sufficient physical and spatial details in meaningful field or pattern models for EOR.
Fully Implicit Two-phase Reservoir Simulation with the Additive Schwarz Preconditioned Inexact Newton Method
Authors: Liu Lulu , Keyes David E. , Sun Shuyu
Published: September 2013

The fully implicit approach is attractive in reservoir simulation for reasons of numerical stability and the avoidance of splitting errors when solving multiphase flow problems, but a large nonlinear system must be solved at each time step, so efficient and robust numerical methods are required to treat the nonlinearity. The Additive Schwarz Preconditioned Inexact Newton (ASPIN) framework, as an option for the outermost solver, successfully handles strong nonlinearities in computational fluid dynamics, but is barely explored for the highly nonlinear models of complex multiphase flow with capillarity, heterogeneity, and complex geometry. In this paper, the fully implicit ASPIN method is demonstrated for a finite volume discretization based on incompressible two-phase reservoir simulators in the presence of capillary forces and gravity. Numerical experiments show that the number of global nonlinear iterations is not only scalable with respect to the number of processors, but also significantly reduced compared with the standard inexact Newton method with a backtracking technique. Moreover, the ASPIN method, in contrast with the IMPES method, saves overall execution time because of the savings in timestep size.
Water-Encroachment Monitoring Applied to Offshore Oil Field
Authors: Al-Dhafeeri A. M. , Al-Beshri F. S. , Al-Sadah A. , Kottuthala J. S. , Ortegon L. R. , Shaqlouf H. , Azam H.
Published: September 2013

A methodology for tracing the advancement of water encroachment from an aquifer by extensive use of behind-casing saturation evaluation logs is introduced. This approach relies on a large number of behind-casing saturation evaluation logs with a large coverage in space and time. A visualization of water saturation, populated through a smooth interpolator in a 3D grid at prescribed timestep, is obtained. Water movement can be visualized in cross sections and maps per reservoir layer. These results aid in the understanding of the path of water invasion and can be used for history-matching a reservoir simulation model at a later stage.

Data required are behind-casing saturation logs (sigma) as well as interpreted elemental volumes from openhole logs, production logs, production history, and perforated intervals. The time-lapsed saturation is cross-checked against water-breakthrough evidence, such as water-production history and production-log runs. The perforated intervals aid in the verification of the depths of entry of water. Unreliable evaluations are screened out. Time-lapsed saturation is interpolated in time for standard timesteps on a well-by-well basis. A form of production history transformed into a form of time-lapsed well log format is used to supplement the water saturation. The saturation logs are filtered for nonreservoir rock and then used to populate the 3D grid. This methodology was used in evaluating water advancement in a reservoir in the Middle East. Petrophysical evaluations were performed to review the openhole logs for consistency and determine the time-lapsed water saturation. Using the water population in the 3D grid, the advancement of the aquifer was evaluated. A series of well fences and average saturation maps per reservoir subzones were created to show the water advancement evolution through time in high resolution. Maps of reservoir potential by subzone were created, and areas of interest for infill drilling were identified.

The methodology proved capable of revealing the water paths in the reservoir where the density of data is large. Upward movement of bottom-aquifer rise, water invaded upper intervals, can be visualized. The results, where applicable, provide a cross-check and aid history matching of reservoir simulation models.
Treatment of wastewater contaminated with detergents and mineral oils using effective and scalable technology
Authors: Abdelmoez Wael , Barakat Nasser A. M. , Moaz Asmaa
Published: September 2013

In this work, effective, cheap and scalable methodology is introduced to treat oily wastewater. The water produced from car-wash processes was utilized as a model because it has various pollutants – oil, lubricants, detergents, solid particles, etc. The results showed that the turbidity and chemical oxygen demand (COD) values dramatically decrease by using the proposed treatment process, which consists of coagulation, flocculation, sand filtration, and oxidation followed by sand as well as activated carbon filtration. Moreover, the operating conditions were optimized. Without adjustment of the pH value of car-wash wastewater, it was found that 200 ppm of ferric chloride, as a coagulant, and 1 ppm of potassium permanganate, as an oxidant, are the optimum doses. The COD and turbidity values of the final treated wastewater were reduced by almost 88 and 100%, respectively. A prototype with 15 L capacity was designed and fabricated to investigate the scaling up and continuity of the proposed treatment strategy. The results were very promising and indicated that the introduced methodology can be industrially applied.
Advanced monitoring of water systems using in situ measurement stations: data validation and fault detection
Authors: Alferes Janelcy , Tik Sovanna , Copp John , Vanrolleghem Peter A.
Published: September 2013

In situ continuous monitoring at high frequency is used to collect water quality information about water bodies. However, it is crucial that the collected data be evaluated and validated for the appropriate interpretation of the data so as to ensure that the monitoring programme is effective. Software tools for data quality assessment with a practical orientation are proposed. As water quality data often contain redundant information, multivariate methods can be used to detect correlations, pertinent information among variables and to identify multiple sensor faults. While principal component analysis can be used to reduce the dimensionality of the original variable data set, monitoring of some statistical metrics and their violation of confidence limits can be used to detect faulty or abnormal data and can help the user apply corrective action(s). The developed algorithms are illustrated with automated monitoring systems installed in an urban river and at the inlet of a wastewater treatment plant.
Photoelectrocatalytic study and scaling up of titanium dioxide electrodes for wastewater treatment
Authors: Pablos C. , van Grieken R. , Marugán J. , Adán C. , Osuna M. , Palma J.
Published: September 2013

Different TiO2 photoelectrodes have been characterized and tested for the photoelectrocatalytic oxidation of methanol. Particulate electrodes (TiO2/Ti and TiO2/ITO) have been shown to notably favour charge-carrier transfer at the electrolyte interface while a thermal electrode (Ti) has been shown to favour charge-carrier separation when applying an electric potential bias according to cyclic voltammetry technique, as a consequence of differences in TiO2 surface between particulate and thermal electrodes. Particulate electrodes lead to a higher photoelectrocatalytic activity for methanol oxidation compared to that of the thermal electrode, probably due to the pure-rutile TiO2 phase composition of the latter and its lower surface area. TiO2/Ti electrode has been shown to be the most effective photoelectrode tested for methanol oxidation since its activity was improved by the combination of the particulate TiO2 layer and the high electrical conductivity of the support. Generally, photocurrent density measured in the photoelectrochemical cell seems to correlate with activity, whereas this correlation is not observed when using a larger photoelectrocatalytic reactor. In contrast, the activity obtained for the scaled-up electrode is found to be similar in terms of surface kinetic constant to that obtained at laboratory scale.
Cost-effective solutions for water quality improvement in the Dommel River supported by sewer–WWTP–river integrated modelling
Authors: Benedetti Lorenzo , Langeveld Jeroen , van Nieuwenhuijzen Arjen F. , de Jonge Jarno , de Klein Jeroen , Flameling Tony , Nopens Ingmar , van Zanten Oscar , Weijers Stefan
Published: September 2013

This project aims at finding cost-efficient sets of measures to meet the Water Framework Directive (WFD) derived goals for the Dommel River (The Netherlands). Within the project, both acute and long-term impacts of the urban wastewater system on the chemical and ecological quality of the river are studied with a monitoring campaign in the urban wastewater system (wastewater treatment plant and sewers) and in the receiving surface water system. An integrated model, which proved to be a powerful tool to analyse the interactions within the integrated urban wastewater system, was first used to evaluate measures in the urban wastewater system using the existing infrastructure and new real-time control strategies. As the latter resulted to be beneficial but not sufficient, this paper investigated the use of additional infrastructural measures to improve the system cost-effectively and have it meet the Directive's goals. Finally, an uncertainty analysis was conducted to investigate the impact of uncertainty in the main model assumptions and model parameters on the performance robustness of the selected set of measures. Apart from some extreme worst-case scenarios, the proposed set of measures turned out to be sufficiently robust. Due to the substantial savings obtained with the results of this project, the pay-back time of the whole monitoring and modelling work proved to be less than 5 months. This illustrates the power of mathematical modelling for decision support in the context of complex urban water systems.
Biological phosphorus and nitrogen removal in sequencing batch reactors: effects of cycle length, dissolved oxygen concentration and influent particulate matter
Authors: Ginige Maneesha P. , Kayaalp Ahmet S. , Cheng Ka Yu , Wylie Jason , Kaksonen Anna H.
Published: September 2013

Removal of phosphorus (P) and nitrogen (N) from municipal wastewaters is required to mitigate eutrophication of receiving water bodies. While most treatment plants achieve good N removal using influent carbon (C), the use of influent C to facilitate enhanced biological phosphorus removal (EBPR) is poorly explored. A number of operational parameters can facilitate optimum use of influent C and this study investigated the effects of cycle length, dissolved oxygen (DO) concentration during aerobic period and influent solids on biological P and N removal in sequencing batch reactors (SRBs) using municipal wastewaters. Increasing cycle length from 3 to 6 h increased P removal efficiency, which was attributed to larger portion of N being removed via nitrite pathway and more biodegradable organic C becoming available for EBPR. Further increasing cycle length from 6 to 8 h decreased P removal efficiencies as the demand for biodegradable organic C for denitrification increased as a result of complete nitrification. Decreasing DO concentration in the aerobic period from 2 to 0.8 mg L−1 increased P removal efficiency but decreased nitrification rates possibly due to oxygen limitation. Further, sedimented wastewater was proved to be a better influent stream than non-sedimented wastewater possibility due to the detrimental effect of particulate matter on biological nutrient removal.
Sorption and degradation of wastewater-associated pharmaceuticals and personal care products in agricultural soils and sediment
Authors: Zhang Ting , Wu Bo , Sun Na , Ye Yong , Chen Huaixia
Published: September 2013

Pharmaceuticals and personal care products (PPCPs) have drawn popular concerns recently as an emerging class of aquatic contaminants. In this study, adsorption and degradation of four selected PPCPs, metronidazole, tinidazole, caffeine and chloramphenicol, have been investigated in the laboratory using two agricultural soils in China and sediment from Changjiang River. Adsorption tests using a batch equilibrium method demonstrated that adsorption of all tested chemicals in soils could be well described with Freundlich equation, and their adsorption affinity on soil followed the order of chloramphenicol > caffeine > tinidazole > metronidazole. Generally, higher Kf value was associated with soils which had higher organic matter contents (except for caffeine acid in this study). Degradation of selected PPCPs in soils generally followed first-order exponential decay kinetics, and half-lives ranging from 0.97 to 10.21 d. Sterilization generally decreased the degradation rates, indicating that microbial activity played a significant role in the degradation in soils. The degradation rate constant decreased with increasing initial chemical concentrations in soil, implying that the microbial activity was inhibited with high chemical loading levels.
Modeling the die-off of E. coli and Ascaris in wastewater-irrigated vegetables: implications for microbial health risk reduction associated with irrigation cessation
Authors: Seidu Razak , Sjølander Ingrid , Abubakari Amina , Amoah Dennis , Larbi John A. , Stenström Thor Axel
Published: September 2013

This study assessed the die-off of Escherichia coli (E. coli) and Ascaris suum on lettuce (Great Lakes 118) and cabbage (Brassica oleracea var capitata) in wastewater-irrigated fields using comparative mathematical die-off models. The study revealed that none of the survival curves of E. coli and A. suum was best fitted with the log-linear model, indicating that the classical first-order kinetic approach is inadequate in many cases. The biphasic die-off model best described the die-off of E. coli on lettuce (kmax1 = 2.62 day−1 and kmax2 = 0.22 day−1) and cabbage (kmax1 = 1.06 day−1 and kmax2 = 0.53 day−1). The die-off of A. suum on lettuce was best described by the biphasic model (kmax1 = 0.48 day−1 and kmax2 = 0.01 day−1) and best described by log linear + tail (kmax = 0.44) on cabbage. A comparative health risk assessment associated with the consumption of lettuce showed significant underestimation of the number of days of irrigation cessation required to achieve E. coli O157:H7 and Ascaris tolerable annual infection risk when using biphasic die-off rates compared with other die-off rates. The study stresses the need to test different die-off models as inputs for quantitative microbial risk assessment (QMRA) particularly for interventions associated with health risk reduction.
A study on the migration and transformation law of nitrogen in urine in municipal wastewater transportation and treatment
Authors: Wuang Ren , Pengkang Jin , Chenggang Liang , Xiaochang Wang , Lei Zhang
Published: September 2013

Many studies suggest that the total nitrogen (TN) in urine is around 9,000 mg/L and about 80% of nitrogen in municipal wastewater comes from urine, because nitrogen mainly occurs in the form of urea in fresh human urine. Based on this fact, the study on the migration and transformation law of nitrogen in urine and its influencing factors was carried out. It can be seen from the experimental results that the transformation rate of urea in urine into ammonia nitrogen after standing for 20 days is only about 18.2%, but the urea in urine can be hydrolyzed into ammonia nitrogen rapidly after it is catalyzed directly with free urease or indirectly with microorganism. Adding respectively a certain amount of urease, activated sludge and septic-tank sludge to urine samples can make the maximum transformation rate achieve 85% after 1 day, 2 days and 6 days, respectively. In combination with some corresponding treatment methods, recycling of nitrogen in urine can be achieved. The results are of great significance in guiding denitrification in municipal wastewater treatment.
Survey monitoring results on the reduction of micropollutants, bacteria, bacteriophages and TSS in retention soil filters
Authors: Tondera Katharina , Koenen Stefan , Pinnekamp Johannes
Published: September 2013

A main source of surface water pollution in Western Europe stems from combined sewer overflow. One of the few technologies available to reduce this pollution is the retention soil filter. In this research project, we evaluated the cleaning efficiency of retention soil filters measuring the concentration ratio of standard wastewater parameters and bacteria according to factors limiting efficiency, such as long dry phases or phases of long-lasting retention. Furthermore, we conducted an initial investigation on how well retention soil filters reduce certain micropollutants on large-scale plants. There was little precipitation during the 1-year sampling phase, which led to fewer samples than expected. Nevertheless, we could verify how efficiently retention soil filters clean total suspended solids. Our results show that retention soil filters are not only able to eliminate bacteria, but also to retain some of the micropollutants investigated here. As the filters were able to reduce diclofenac, bisphenol A and metoprolol by a median rate of almost 75%, we think that further investigations should be made into the reduction processes in the filter. At this point, a higher accuracy in the results could be achieved by conducting bench-scale experiments.
Methodology to elaborate the bathing water profile on urban beaches, according to the requirements of the European Directive 2006/7/EC: the case of Santander beaches (Spain)
Authors: López Iago , Álvarez César , Gil José L. , Revilla José A.
Published: September 2013

The approval of the current Bathing Water Directive (Directive 2006/7/EC) set the necessity to define the bathing water profile. The goals established in the definition of the profile are: (i) to know the processes that determine the concentration of bacteriological indicators in the aquatic environment, (ii) to obtain relationships between the cause of pollution and its effects, and (iii) to evaluate the fulfilment of the Directive and to set the Quality Monitoring and Assessment Program, according to the bacteriological characteristics of the bathing water. In this paper an approach to elaborate the bathing water profile and its application to several bathing waters located in Santander municipality (North Spain) is shown. The methodology involves the assessment of advection, diffusion and reaction processes of bacteriological organisms in the aquatic environment by using mathematical models and the selection of an indicator to evaluate the probability to exceed the bacteriological concentrations established in Directive 2006/7/EC, which is useful for the ‘source apportionment’ assessment. In the definition of the bathing water profile we have considered the sanitation system operating under normal conditions, which includes storm water overflows, uncontrolled discharges and the discharge produced when the pumping system of the wastewater breaks. Finally, according to the bacteriological characteristics of the bathing water it is necessary to develop the Quality Monitoring and Assessment, which has been done taking into account the requirements established in Directive 2006/7/EC and the uncertainties detected in such a method regarding the number of samples to be considered.
Water, soil and nutrient losses caused by Wenchuan Earthquake: a case study in Pengzhou
Authors: Guo Haixia , Sun Geng , Shi Fusun , Lu Tao , Wang Qian , Wu Yan , Wu Ning
Published: September 2013

Wenchuan Earthquake triggered a large number of geological hazards, dramatically stimulating soil erosion. This study was carried out in Pengzhou County, Sichuan Province. By comparison of sediment, runoff and nutrient losses in earthquake-damaged forests (EF) and unaffected forests (UF), the actual status of soil erosion after the Wenchuan Earthquake was investigated by runoff plots. Results showed that water and soil losses were dramatically increased after earthquake. During the study period (from August to November 2010), UF runoffs were 19.26, 36.76, 10.68 and 7.51 L m−2, while total runoffs in EF sites were 30.41, 25.79, 5.03 and 2.67 L m−2 respectively, which were 15, 15, 18 and 19 times more than those in UF. Total sediment losses in EF sites were 28.94, 25.16, 4.11 and 1.98 t km−2 respectively while in UF they were 707.69, 610.05, 113.43 and 58.95 t km−2 respectively during the same study period, i.e. 23, 23, 32 and 29 times more than those in UF. Path analysis showed that both vegetation and rainfall exerted an indirect influence on sediment loss by significantly influencing runoff, which correlated with sediment loss very significantly. Although no obvious differences of the nutrients’ concentration in runoff water (soluble organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK)) between EF and UF sites were observed, total losses of the four nutrients were significantly higher in EF than in UF sites (for example, in EF sites, SOC, TN, TP and TK losses were 970.52, 114.46, 2.26 and 307.00 g m−2 respectively, while in UF they were 38.13, 4.22, 0.10 and 13.28 g m−2) due to significantly higher runoff in EF sites. In conclusion, soil erosion was significantly more serious due to the loss of forested lands resulting from the Wenchuan Earthquake, delaying the restoring process of forest cover and weakening the ecological linkage between upstream and downstream.
Cellulose production by Gluconacetobacter kakiaceti GM5 in two batch process using vinasse as culture media
Authors: Velásquez-Riaño Möritz , Lombana-Sánchez Nelson , Villa-Restrepo Andrés Felipe , Fernández-Calle Erika Pamela
Published: September 2013

The present study was conducted to evaluate the cellulose production by Gluconacetobacter kakiaceti GM5 by means of two aerobic treatments: the static discontinuous fermentation process (treatment 1) and the discontinuous fermentation process in a rotary shaker (treatment 2). All these experiments were carried out using vinasse as experimental culture media (VM) and were compared with standard media containing glucose at 2% (standard medium (SM)). A sample of each treatment was extracted every 24 h over a period of 168 h. The maximum rates of cellulose produced in treatment 1 using SM added up to 3.63 ± 0.18 g l−1, and to 4.15 ± 0.16 g l−1 when VM was used. The amount of cellulose produced in treatment 2 using SM was 2.95 ± 0.09 g l−1 (which suggests an increase of 37%), and added up to 1.84 ± 0.07 g l−1 when using VM. A better global yield of both treatments in terms of sugar consumption after 168 h was obtained when using VM: 32% in treatment 1, whereas in treatment 2 it was 9%. A 20% decrease on vinasse COD (Chemical Oxygen Demand) values was found to be yet another important advantage of working with this strain.
Model-based monitoring of stormwater runoff quality
Authors: Birch Heidi , Vezzaro Luca , Mikkelsen Peter Steen
Published: September 2013

Monitoring of micropollutants (MP) in stormwater is essential to evaluate the impacts of stormwater on the receiving aquatic environment. The aim of this study was to investigate how different strategies for monitoring of stormwater quality (combining a model with field sampling) affect the information obtained about MP discharged from the monitored system. A dynamic stormwater quality model was calibrated using MP data collected by automatic volume-proportional sampling and passive sampling in a storm drainage system on the outskirts of Copenhagen (Denmark) and a 10-year rain series was used to find annual average (AA) and maximum event mean concentrations. Use of this model reduced the uncertainty of predicted AA concentrations compared to a simple stochastic method based solely on data. The predicted AA concentration, obtained by using passive sampler measurements (1 month installation) for calibration of the model, resulted in the same predicted level but with narrower model prediction bounds than by using volume-proportional samples for calibration. This shows that passive sampling allows for a better exploitation of the resources allocated for stormwater quality monitoring.
Activated carbon prepared from coffee pulp: potential adsorbent of organic contaminants in aqueous solution
Authors: Gonçalves Maraisa , Guerreiro Mário César , Ramos Paulize Honorato , de Oliveira Luiz Carlos Alves , Sapag Karim
Published: September 2013

The processing of coffee beans generates large amounts of solid and liquid residues. The solid residues (pulp, husk and parchment) represent a serious environmental problem and do not have an adequate disposal mechanism. In this work, activated carbons (ACs) for adsorption of organic compounds were prepared from coffee pulp by controlled temperature at different pulp/Na2HPO4 ratios (4:1, 2:1, 5:4 and 1:1). The N2 adsorption/desorption isotherms showed ACs with high quantities of mesopores and micropores and specific surface areas of 140, 150, 450 and 440 m2g−1 for AC 4:1, AC 2:1, AC 5:4 and AC 1:1, respectively. The prepared material AC 5:4 showed a higher removal capacity of the organic contaminants methylene blue (MB), direct red (DR) and phenol than did a Merck AC. The maximum capacities for this AC are approximately 150, 120 and 120 mg g−1 for MB, DR and phenol, respectively. Thus, a good adsorbent was obtained from coffee pulp, an abundant Brazilian residue.
Activated carbon fiber felt and polymer fiber as biofilm carrier in a modified University of Cape Town process for sewage treatment
Authors: Zhou Dongkai
Published: September 2013

Biofilms on fiber-based carriers have attracted much concern in wastewater treatment processes recently. In this study: (1) a novel sandwich structure fiber-based biofilm carrier was produced, which consisted of an inner core composed of polyacrylonitrile-based activated carbon fiber felt (PAN-ACFF) and an outer coat made of polyester reticular cloth with polypropylene fiber loops; (2) the novel carrier was filled in a step-feeding pilot-scale modified University of Cape Town process (MUCT) for sewage treatment; the MUCT contained a series of pre-anoxic/anaerobic/anoxic-1/anoxic-2/oxic tanks, wherein nitrification liquor was recycled to the anoxic-2 tank and an extra liquor return from the anoxic-1 to the pre-anoxic tank was set up; and (3) the removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were continuously tested for two periods as operational parameters alternated. The optimum values were collected in Period II, when the influent loads were 2,100.6 ± 120.3 gCOD/(d m3), 205.5 ± 20.4 gTN/(d m3), 39.9 ± 3.9 gTP/(d m3), the removal percentages were 93.1 ± 1.1% of COD, 39.4 ± 3.5% of TN, and 84.6 ± 3.4% of TP. For COD, NH4+-N, and TP, the specific removal loads of filler were 291.5 ± 18.2, 22.9 ± 3.1, 4.8 ± 0.5 (g d)/kg.
Removal of titanium dioxide nanoparticles by coagulation: effects of coagulants, typical ions, alkalinity and natural organic matters
Authors: Wang H. T. , Ye Y. Y. , Qi J. , Li F. T. , Tang Y. L.
Published: September 2013

To investigate the possibility of removing titanium dioxide nanoparticles (TiO2 NPs) from water by coagulation, as well as to find the optimal coagulant and experimental conditions for TiO2 NP removal, four types of coagulant were adopted: polyferric sulfate (PFS), ferric chloride (FeCl3), polyaluminum chloride (PACl), and alum (Al2(SO4)3). It was found that the removal of TiO2 NPs by coagulation was affected by ionic strength, alkalinity, as well as types and dosages of coagulants. PFS and FeCl3 achieved much higher removal efficiency of TiO2 NPs than PACl and Al2(SO4)3 did. For 30 mg/L TiO2 NPs, a dosage of 0.3 mM PFS (as Fe) achieved 84% removal after coagulation followed by 30 min settlement. Optimal ionic strength (0.1 M NaCl or 0.03 M CaCl2) is of vital importance for the performance of PFS. Na2SO4 is unfavorable for the performance of PFS. Optimal alkalinity (0.01–0.03 M NaHCO3) is necessary for FeCl3 to remove TiO2 NPs. Natural organic matter, as represented by humic acid (HA) up to 11 mg/L, reduces the removal of TiO2 NPs by coagulation. These findings indicate that coagulation is a good option for the removal of TiO2 NPs from water, and more attention should be paid to the effects of water quality when using coagulation to remove TiO2 NPs from aqueous matrices. This provides a possible solution to alleviate the potential hazard caused by TiO2 NPs.
Modeling trichloroethene reduction in a hydrogen-based biofilm
Authors: Tang Youneng , Krajmalnik-Brown Rosa , Rittmann Bruce E.
Published: September 2013

We constructed a multispecies biofilm model for simultaneous reduction of trichloroethene (TCE) and nitrate (NO3−) in the biofilm of a H2-based membrane biofilm reactor (MBfR). The one-dimensional model includes dual-substrate Monod kinetics for a steady-state biofilm with multiple solid and dissolved components. The model has five solid components: autotrophic denitrifying bacteria (ADB), heterotrophic denitrifying bacteria (HDB), Dehalococcoides (DHC), inert biomass (IB), and extracellular polymeric substances (EPS). The model has eight dissolved components: NO3−, TCE, dichloroethene (DCE), vinyl chloride (VC), ethene, hydrogen (H2), substrate-utilization-associated products (UAP), and biomass-associated products (BAP). We used this model to simulate a bench-scale experiment in a H2-based MBfR. The model simulated the trends well: almost complete removal of nitrate, incomplete reduction of TCE, and almost no accumulation of DCE and VC. To gain insight into reductive dehalogenation in a H2-based MBfR, we also simulated the concentrations of nitrate, TCE, DCE, VC, and ethene in the reactor effluent while varying the influent nitrate concentration. Simultaneous low concentrations of nitrate and the three chlorinated ethenes can occur as long as the influent ratio of NO3− to TCE is not too large, so that DHC are a significant fraction of the biofilm.
Experience Using the Heidelberg Retina Angiograph 2 with a Wide-Field Contact Lens System in Diabetic Retinopathy Cases
Authors: Shiibashi Miyo , Yoshimoto Miwako , Shigeeda Takashi , Kitano Shigehiko , Kato Satoshi
Published: September 2013

Introduction:

HRA (Heiderberg Retina Angiograph) 2 uses a confocal scanning laser system which can provide high quality digital images but its imaging field is only 30°at most. HRA2 with a wide-field contact lens system allows an imaging field of up to 150°.

Methods:

We examined the advantages and disadvantages of HRA2, with a wide-field contact lens, for the evaluating diabetic retinopathy (DR).

Results:

HRA2 was beneficial for obtaining images of the entire retina simultaneously, without missing peripheral retinal non-perfusion and neovascularization. On the other hand, clear images connot be acquired in cases with media opacities such as corneal dystrophy, cataract and asteroid hyalosis, or in those with yellow tinted IOL.

Conclusions:

HRA2 with a wide-field contact lens is useful for visualizing peripheral retinal lesions in DR cases.
Laser ablation initiated fast discharge for spectrochemical applications
Authors: Vinic Milica , Ivkovic Milivoje
Published: September 2013

The results of an experimental study of the optical emission enhancement
possibilities during the single pulse laser induced breakdown spectroscopy of
the aluminum alloy are presented. This study is performed in air, argon and
helium at different pressures with and without the additional fast electric
discharge. The discharge was initiated by plasma plume created by laser
ablation of target. The influences of various capacitors and discharge
voltages on enhancement of the studied spectral line intensities were also
studied. The application of the fast discharge through optical emission
enhancement enables lowering of detection limits thus making this
spectrochemical method comparable with the other analytical techniques.
Analytical application of the reaction system methylene blue B-K2S2O8 for the spectrophotometric kinetic determination of silver in citric buffer media
Authors: Rancic Sofija , Nikolic-Mandic Snezana , Bojic Aleksandar
Published: September 2013

A new, simple, rapid, sensitive and selective spectrophotometric kinetic
method for Ag(I) traces determination at room temperature was elaborated in
this paper. It is based on catalytic effect of silver ions upon the oxidation
of methylene blue B (MBB) by K2S2O8 (PPS) in citric buffer (BUF) solution.
The method was confirmed by determination of Ag(I) in PbO. The obtained
results were compared to those obtained by ICP-OES method and good agreement
of results was found.