Performance assessment of wastewater treatment plant of Hawassa St. George Brewery, Hawassa, Ethiopia

The aim of this study was to evaluate the performance efficiency of the wastewater treatment plant of Hawassa St. George brewery by collecting wastewater samples from the influent and outlet of each treatment unit and analyzed using standard methods for major physicochemical parameters. Results of the present study revealed that except for temperature (36-38 0C), all of the other analyzed parameters of raw wastewater exceeded the national discharge limit indicating the necessity of treating the raw wastewater generated by the brewery. In most cases, the values decreased as the wastewater passed over the treatment units of the plant indicating an involvement of the units in the removal of pollutants. The brewery’s treated final effluent had a mean value of 8.6±0.08 (pH), 24.9±0.6oC (temperature), 203.0 mg/L (COD), 17.7 mg/L (NH4-N), 3.62 mg/L (SO24), 220.6μS/cm (EC), 49.8 mg/L (BOD5), and 529.6 NTU (turbidity), which were within national industrial wastewater discharge limits. However, the values of some parameters namely, TN (41.0 mg/L), TP (24.3 mg/L), H2S (3.1 mg/L) and TDS (110.6 mg/L), were higher than the limits. The overall pollutant removal efficiency of the treatment plant was 96.0% (BOD), 92.3% (TSS), 92.0% (COD), 88.5% (EC), 80.6% (TDS), 49.6% (turbidity), 43.0% (SO42-), 42.7% (NH4-N), 33.6% (temperature), 32.8% (TN), 31.8% (pH), and 30.4% (TP). This result shows that the overall removal efficiency was higher only for BOD5, TSS, COD, TDS, and EC, all others (especially nutrients) had less than 50.0% efficiencies. Higher nutrient concentration exceeding the discharge limits in final effluent and poor removal efficiency of the treatment plant indicates that the Hawassa St. Gorge brewery waste treatment plant is not effective enough to lower concentrations of these parameters below the discharge limit. Therefore, in order to make the plant more efficient and to reduce the effect of effluent, the factory should take some technological, technical and recycling measures.Keywords: Brewery, Hawassa, Performance, St. George, Treatment, Wastewate

Biogas and bio-fertilizer production potential of abattoir waste as means of sustainable waste management option in Hawassa City, southern Ethiopia

The purpose of this study was to assess abattoir waste generation in Hawassa Municipality Abattoir (HMA) andits potential to produce biogas and bio-fertilizer employing a cross-sectional design and mathematical computation based on standard coefficients. The study demonstrated that HMA generates 885,881.6Kg of abattoir waste per year and using anaerobic digestion about 46,951.72m3/year of biogas can be produced. This waste has the potential of generating a total energy of 246,027.01KWh/year. The biogas or energy from the waste can replace the biomass (firewood and charcoal) and the expensive fossil fuels. Using the produced46, 951.72m3/year biogas could reduce the annual CO2 emission of 150,600.10Kg/kWh from kerosene, 150,600.10Kg/kWh from petrol, 132,882.50Kg/kWh from diesel or 132,882.50Kg/kWh from LPG use. The abattoir will be able to produce an estimated 65,112.3 Kg/year dry bio-fertilizer from biogas technology and this bio-fertilizer can be supplied to local farmers for crop production or can be used by city municipality for growing plants used for beautification. This obtainable bio- fertilizer is valued 29,951.66 USDper annum and to a certain extent will contribute to the reduction of domestic demand of chemical fertilizer thus will reduce the annual budget. As a long-term and sustainable waste management solution, installing anaerobic digestion plant is recommended, but using proper disposal method among the existing would serve as a short-term solution.Keywords: - Abattoir, Bio-fertilizer, Biogas, Energy, Hawassa, Wast

A characterization of quadric constant mean curvature hypersurfaces of spheres

Let $\phi:M\to\mathbb{S}^{n+1}\subset\mathbb{R}^{n+2}$ be an immersion of a complete $n$-dimensional oriented manifold. For any $v\in\mathbb{R}^{n+2}$, let us denote by $\ell_v:M\to\mathbb{R}$ the function given by $\ell_v(x)=\phi(x),v$ and by $f_v:M\to\mathbb{R}$, the function given by $f_v(x)=\nu(x),v$, where $\nu:M\to\mathbb{S}^{n}$ is a Gauss map. We will prove that if $M$ has constant mean curvature, and, for some $v\ne{\bf 0}$ and some real number $\lambda$, we have that $\ell_v=\lambda f_v$, then, $\phi(M)$ is either a totally umbilical sphere or a Clifford hypersurface. As an application, we will use this result to prove that the weak stability index of any compact constant mean curvature hypersurface $M^n$ in $\mathbb{S}^{n+1}$ which is neither totally umbilical nor a Clifford hypersurface and has constant scalar curvature is greater than or equal to $2n+4$.Comment: Final version (February 2008). To appear in the Journal of Geometric Analysi

Strategies for the evolution of sex

We find that the hypothesis made by Jan, Stauffer and Moseley [Theory in Biosc., 119, 166 (2000)] for the evolution of sex, namely a strategy devised to escape extinction due to too many deleterious mutations, is sufficient but not necessary for the successful evolution of a steady state population of sexual individuals within a finite population. Simply allowing for a finite probability for conversion to sex in each generation also gives rise to a stable sexual population, in the presence of an upper limit on the number of deleterious mutations per individual. For large values of this probability, we find a phase transition to an intermittent, multi-stable regime. On the other hand, in the limit of extremely slow drive, another transition takes place to a different steady state distribution, with fewer deleterious mutations within the asexual population.Comment: RevTeX, 11 pages, multicolumn, including 12 figure

Star cluster formation and star formation: the role of environment and star-formation efficiencies

“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1007/s10509-009-0088-5By analyzing global starburst properties in various kinds of starburst and post-starburst galaxies and relating them to the properties of the star cluster populations they form, I explore the conditions for the formation of massive, compact, long-lived star clusters. The aim is to determine whether the relative amount of star formation that goes into star cluster formation as opposed to field star formation, and into the formation of massive long-lived clusters in particular, is universal or scales with star-formation rate, burst strength, star-formation efficiency, galaxy or gas mass, and whether or not there are special conditions or some threshold for the formation of star clusters that merit to be called globular clusters a few billion years later.Peer reviewe

Spontaneous Coherence and Collective Modes in Double-Layer Quantum Dot Systems

We study the ground state and the collective excitations of parabolically-confined double-layer quantum dot systems in a strong magnetic field. We identify parameter regimes where electrons form maximum density droplet states, quantum-dot analogs of the incompressible states of the bulk integer quantum Hall effect. In these regimes the Hartree-Fock approximation and the time-dependent Hartree-Fock approximations can be used to describe the ground state and collective excitations respectively. We comment on the relationship between edge excitations of dots and edge magneto-plasmon excitations of bulk double-layer systems.Comment: 20 pages (figures included) and also available at http://fangio.magnet.fsu.edu/~jhu/Paper/qdot_cond.ps, replaced to fix figure

Star Formation and Dynamics in the Galactic Centre

The centre of our Galaxy is one of the most studied and yet enigmatic places in the Universe. At a distance of about 8 kpc from our Sun, the Galactic centre (GC) is the ideal environment to study the extreme processes that take place in the vicinity of a supermassive black hole (SMBH). Despite the hostile environment, several tens of early-type stars populate the central parsec of our Galaxy. A fraction of them lie in a thin ring with mild eccentricity and inner radius ~0.04 pc, while the S-stars, i.e. the ~30 stars closest to the SMBH (<0.04 pc), have randomly oriented and highly eccentric orbits. The formation of such early-type stars has been a puzzle for a long time: molecular clouds should be tidally disrupted by the SMBH before they can fragment into stars. We review the main scenarios proposed to explain the formation and the dynamical evolution of the early-type stars in the GC. In particular, we discuss the most popular in situ scenarios (accretion disc fragmentation and molecular cloud disruption) and migration scenarios (star cluster inspiral and Hills mechanism). We focus on the most pressing challenges that must be faced to shed light on the process of star formation in the vicinity of a SMBH.Comment: 68 pages, 35 figures; invited review chapter, to be published in expanded form in Haardt, F., Gorini, V., Moschella, U. and Treves, A., 'Astrophysical Black Holes'. Lecture Notes in Physics. Springer 201

Prevalence and predictors for sustained remission in rheumatoid arthritis

Objective Remission is a key goal in managing rheumatoid arthritis (RA), with sustained remission as the preferred sequelae of short-term remission. However little is known about the predictors of sustained remission for patients reaching remission. Using two independent cohorts, we aimed to evaluate the prevalence and predictors for sustained remission. Methods The study cohort consisted of subjects with RA from the Brigham and Women’s Hospital Rheumatoid Arthritis Sequential Study (BRASS) and the Korean Observational Study Network for Arthritis (KORONA). We analyzed subjects who reached remission in 2009 with follow up data for two consecutive years. Remission was defined by the Disease Activity Score 28- (DAS28-CRP) of less than 2.6. Sustained remission was defined as three consecutive annual visits in remission. Predictors for sustained remission were identified by multivariate logistic regression analysis. Results A total of 465 subjects were in remission in 2009. Sustained remission was achieved by 53 of 92 (57.5%) in BRASS and by 198 of 373 (53.1%) in KORONA. In multivariate analyses, baseline predictors of sustained remission were: disease duration less than 5 years [odds ratio (OR) 1.96, 95% confidence interval (95% CI) 1.08–3.58], Modified Health Assessment Questionnaire (MHAQ) score of 0 (OR 1.80, 95% CI 1.18–2.74), and non-use of oral glucocorticoid (OR 1.58, 95% CI 1.01–2.47). Conclusion More than half of RA subjects in remission in 2009 remained in remission through 2011. Short disease duration, no disability, and non-use of oral glucocorticoid at baseline were associated with sustained remission