Influence of biomass density and food to microorganisms ratio on the mixed culture type I methanotrophs enriched from activated sludge

Methanotrophic based process can be the remedy to offset the wastewater treatment facilities increasing energy requirements due to methanotroph's unique ability to integrate methane assimilation with multiple biotechnological applications like biological nitrogen removal and methanol production. Regardless of the methanotrophic process end product, the challenge to maintain stable microbial growth in the methanotrophs cultivation bioreactor at higher cell densities is one of the major obstacles facing the process upscaling. Therefore, a series of consecutive batch tests were performed to attentively investigate the biomass density influence on type I methanotrophs bacterial growth. In addition, food to microorganisms(F/M), carbon to nitrogen(C/N) and nitrogen to microorganisms(N/M) ratio effect on the microbial activity was studied for the first time. It was clarified that the F/M ratio is the most influencing factor on the microbial growth at higher biomass densities rather than the biomass density increase, whereas C/N and N/M ratio change, while using nitrate as the nitrogen source,does not influence methanotrophs microbial growth. These study results would facilitate the scaling up of methanotrophic based biotechnology by identifying that F/M ratio as the key parameter that influences methanotrophs cultivation at high biomass densities.     

Heavy Metals Monitoring using Bivalves from Mediterranean Sea and Red Sea

The concentrations of heavy metals (Cd, Co, Cu, Fe, Mn, Ni, Pd and Zn) were measured in the Bivalves (Modiolus auriculatus and Donax trunculus) collected from the Egyptian coasts of Mediterranean Sea and Brachiodonates sp. from the Egyptian coasts of Red Sea. The average concentrations of the heavy metals analyzed exhibited the following decreasing order: Fe > Zn > Cu > Mn > Ni > Co > Pb > Cd for both Mediterranean Sea and Red Sea. The analyses of Cd, Co, Ni, Pb, and Zn showed higher average concentrations for samples collected from Red Sea than that collected from Mediterranean Sea, while Fe, Cu and Mn showed the reverse results. Fe was used as a normalizing agent for all studied metals and exhibited presence of two locations from each of Mediterranean Sea and Red Sea have anthropogenic inputs of heavy metals. These results suggest that the coastal area in both Mediterranean Sea and Red Sea of Egypt might be considered relatively unpolluted with heavy metal.     

DNA adducts as early bioindicators of chemical exposure

Sensitive analytical methods indicate the presence of hundreds of chemical contaminants in our environment. However, concentration of these pollutants is usually at the low parts per million or parts per billion level. At such low levels, toxicants induce long-term (chronic) rather than short-term (acute) toxicities. Experiments are designed to evaluate chronic toxicity using early bioindicators. Recently, fish have been used as experimental animals because some species show early (weeks as opposed to years in other research animals), sensitive responses. Thus, medaka (Oryzias latipes), following exposure to diethylnitrosamine (DEN), exhibited liver tumors in several weeks; more interestingly its DNA was modified (to a DNA-adduct) after only 24–48 hours exposure. Such adducts show promise as early bioindicators because they are formed within hours of exposure. The formation of DNA-adducts were monitored in medaka and rainbow trout (Salmo gairdneri) exposed to DEN by aqueous or intra-peritoneal routes. Using HPLC-Fluorimetry, O ⁶-ethylguanine (O ⁶-EtGua) was detected and monitored in acid thermal hydrolysates of DNA isolates. (Detection limit for O ⁶-EtGua was as low as 3 ng, 1.7×10^-11 moles). Fourier transform cyclotron resonance mass spectrometry with IR laser desorption/ionization was used advantageously to establish the structure of nucleotides, bases and nucleosides directly, without further cumbersome derivatizations. Other aspects of DNA-adducts are discussed.     

Secondary imbibition in NAPL-invaded mixed-wet sediments

A previously developed pore network model is used here to study the spontaneous and forced secondary imbibition of a NAPL-invaded sediment, as in the displacement of NAPL by waterflooding a mixed-wet soil. We use a 3D disordered pore network with a realistic representation of pore geometry and connectivity, and a quasi-static displacement model that fully describes the pore-scale physics. After primary drainage (NAPL displacing water) up to a maximum capillary pressure, we simulate secondary imbibition (water displacing NAPL). We conduct a parametric study of imbibition by varying systematically the controlling parameters: the advancing contact angles, the fraction of NAPL-wet pores, the interfacial tension, and the initial water saturation. Once the secondary imbibition is completed, the controlling displacement mechanisms, capillary pressures, relative permeabilities, and trapped NAPL saturations are reported. It is assumed that NAPL migrates into an initially strongly water-wet sediment, i.e., the receding contact angles are very small. However, depending on the surface mineralogy and chemical compositions of the immiscible fluid phases, the wettability of pore interiors is altered while the neighborhoods of pore corners remain strongly water-wet-resulting in a mixed-wet sediment. Here, we compare three different levels of wettability alteration: water-wet (advancing contact angles (20 degrees to 55 degrees), intermediate-wet (55 degrees to 120 degrees), and NAPL-wet (120 degrees to 155 degrees). The range of advancing contact angles and the fraction of NAPL-wet pores have dramatic effects on the NAPL-water capillary pressures and relative permeabilities. The spatially inhomogeneous interfacial tension has a minor impact on the trapped NAPL saturation and relative permeability to NAPL, and a slight effect on the relative permeability to water. The initial water saturation has a slight effect on the two-phase flow characteristics of water-wet sediments; however, with more NAPL-wet pores in the sediment, it starts to have a profound effect on the water and NAPL relative permeabilities.     

Greenhouse gas emission from small clinics solid waste management scenarios in an urban area of an underdeveloping country: A life cycle perspective

This study aimed to investigate the effects on the environment of small clinics solid waste management by applying a life cycle analysis approach. Samples were collected from 371 private clinics situated in densely populated areas of Hyderabad, Pakistan. The solid waste from surveyed clinics was categorically quantified on daily basis for 30 consecutive days. The functional unit for waste was defined as 1 tonne. System limitations were defined as landfilling, incineration, composting, material recovery, and transportation of solid waste. The treatment and disposal methods were assessed according to their greenhouse gas emission rate. For the evaluation, three different scenarios were designed. The second scenario resulted in the highest emission value of 1491.78 kg CO₂ eq/tonne of solid waste due to mixed waste incineration, whereas the first scenario could not offer any saving because of uncovered landfilling and 67.5% higher transport fuel consumption than the proposed network. The proposed third scenario was found to be a better solution for urban clinics solid waste management, as it resulted in savings of 951.38 kg CO₂ eq/tonne of solid waste. This integrated design is practicable by resource-constrained economy. This system consists of composting, material recovery, and incineration of hazardous waste. The proposed system also includes a feasible transportation method for urban area collection networks. The findings of the present study can play a vital role in documenting evidence and for policymakers to plan the solid waste management of clinics, as previously no studies have been conducted on this particular case.

Implications: This study aims to highlight the impact of small clinics solid waste management scenarios on the environment in a developing country’s urban area. Life cycle analysis is used for comparison of greenhouse gase emission from different scenarios, including the purposed integrated method. Small clinics play a very important role in health care, and their waste management is a very serious issue; however, there are no previous studies on this particular case to the best knowledge of the authors. This study can be considered as forerunner effort to quantify the environmental footprint of small clinics solid waste in urban areas of a developing country.     

Modeling Change-Pattern-Value Dynamics on Land Use: An Integrated GIS and Artificial Neural Networks Approach

The use of spatial methods to detect and characterize changes in land use has been attracting increasing attention from researchers. The objectives of this article were to formulate the dynamics of land use on the temporal and spatial dimensions from the perspectives of the Change-Pattern-Value (CPV) and driving mechanism, based on multitemporal remote sensing data and socioeconomic data. The Artificial Neural Networks were used to identify the factors driving changes in land use. The Pearl River Delta Region of southeast China, which was experiencing rapid economic growth and widespread land conversion, has been selected as the study region. The results show that from 1985 to 2000 in the study region (1) the most prominent characteristics of change in land use were the expansion of the urban land at the expense of farmland, forests, and grasslands, (2) the land-use pattern was being optimized during this period, (3) in an analysis of value, built-up land can yield a return of more than 30 times that of farmland, water area, and forests lands, and (4) rapid economic development, growth in population, and the development of an infrastructure were major driving factors behind ecological land loss and the nonecological land expansion.     

A SIMULATION OF SMOOTH-VARIABLE INTENSITY RAINFALL PATTERNS1

ABSTRACT: Continuous rainfall patterns are currently simulated by approximating them by stair-stepped (piece-wise) patterns. The effects of this approximation on infiltration and runoff processes are not well known. A new technique for simulating smooth-variable intensity rainfall patterns is presented. This technique is based on the fundamental principles of a moving water head in a container. The proposed technique is general and capable of simulating any rainfall pattern. However, as the rainfall pattern gets more complicated, the equipment required for simulation becomes more involved. The proposed technique has been tested experimentally. A close agreement was found between the theoretical and experimental simulations. It is concluded that the proposed technique might be very useful in studying the infiltration and runoff processes under variable intensity rainfall, especially for simple convex patterns.     

The rhetoric of participation re-examined: The state,NGOs and water users at Varanasi,Uttar Pradesh,India

Summary People's participation is usually regarded as a sine qua non for the success and sustainability of development projects. Yet in practice, it raises a number of questions. Who are the people? Why is their participation sought, and how or at what level, is such participation desired? This paper seeks to examine the rhetoric of participation in the implementation of the Ganga Action Plan (GAP) at Varanasi, in the north-eastern State of Uttar Pradesh, India. Launched in 1985, the GAP is the first major attempt to systematically control and monitor the pollution of a significant river in the country. In addition, it claimed to be a people's programme because of the powerful and deep-seated cultural and religious meaning associated with the Ganga. Varanasi, however, is indicative of its failure to deliver this promise — the GAP is only acceptable to authority because it does not challenge the existing institutional order, and its participatory content is symbolic rather than substantive. Non-govemental organisations, traditionally viewed as intermediary actors between the micro and macro levels, work within the socio-political framework of the city. In the process, water-user groups such as the washermen who derive an economic livelihood from washing clothes in the Ganga, are literally excluded from the definition and process of participation.She obtained her PhD, the basis of the current research, at the University of Cambridge, UK.     

Correlation between oxygen utilization and electron transport activity in marine phytoplankton

Measurement of a respiratory control ratio is deemed very useful in determination of energy balance in respiration. We have defined and computed a control ratio as the ratio of the rate of oxygen consumption in vivo to the calculated maximum rate of oxygen consumption in vitro as measured by enzymatic electron transport rates. In order for a control ratio to serve a useful purpose in calculating in situ oxygen consumption in a water parcel, the ratio must be fairly constant. Our results indicated that this is precisely so in healthy cultures of the 9 species of phytoplankton studied. The data presented in this communication further point towards the potential for making reasonable estimates of phytoplankton oxygen consumption in an ocean water parcel by directly utilizing in vitro electron transport activity measurements.     

Species differences in accumulation of nitrogen pools in phytoplankton

The changes in the intracellular concentrations of nitrate, ammonium, free amino acids, protein, DNA, RNA and total nitrogen were measured in batch cultures of seven species of marine phytoplankton as they progressed from being nitrogen sufficient to being nitrogen starved. After several days of nitrogen starvation, either nitrate or ammonium was added to the cultures, and the measurements were continued for 10 to 36 h. By this means it was possible to assess the long-term and short-term changes in cellular nitrogen compounds and how they relate to phytoplankton nitrogen uptake and growth. Considerable species differences were observed in the amounts and kinds of nitrogen compounds which were stored and the degree to which the utilization of these compounds could support growth if the external nitrogen supply is low or variable. Despite the species variation, the results suggest that the concentrations or ratios of a number of intracellular nitrogen compounds can be used to assess the nitrogen deficiency and/or growth rate of natural phytoplankton populations.Contribution No. 1373 from the School of Oceanography, University of Washington and Contribution No. 83006 from the Bigelow Laboratory for Ocean Sciences