Development of an empirical mathematical model for describing and optimizing the hygiene potential of a thermophilic anaerobic bioreactor treating faeces.

Poor sanitation and insufficient disposal of sewage and faeces are primarily responsible for water associated health problems in developing countries. Domestic sewage and faeces are prevalently discharged into surface waters which are used by the inhabitants as a source for drinking water. This paper presents a decentralized anaerobic process technique for handling of such domestic organic waste. Such an efficient and compact system for treating faeces and food waste may be of great benefit for developing countries. Besides a stable biogas production for energy generation, the reduction of bacterial pathogens is of particular importance. In our research we investigated the removal capacity of the reactor concerning pathogens, which has been operated under thermophilic conditions. Faecal coliforms and intestinal enterococci have been detected as indicator organisms for bacterial pathogens. By the multiple regression analysis technique an empirical mathematical model has been developed. The model shows a high correlation between removal efficiency and both, hydraulic retention time (HRT) and temperature. By this model an optimized HRT for defined bacterial pathogens effluent standards can be easily calculated. Thus, hygiene potential can be evaluated along with economic aspects. In this paper not only results for describing the hygiene potential of a thermophilic anaerobic bioreactor are presented, but also an exemplary method to draw the right conclusions out of biological tests with the aid of mathematical tools.     

Surface roughness of a hot-dipped galvanized sheet steel as a function of deformation mode

A hot-dipped galvanized zinc-coated sheet steel was deformed with three different laboratory test systems: a Marciniak punch system, a flat-die friction test system, and a cupping system. These systems were able to impose various combinations of deformation modes to the sheet. The deformation modes include: (1) strain without die contact, (2) sliding, (3) pressing, and (4) bending. Strain measurements from the electrolitically gridded specimens were made at the same locations as surface profilometry measurements, allowing a direct correspondence of surface roughness with strain. Quantification of the roughening as a function of strain, sliding and bending was determined. The roughening rate depends upon the strain level as well as the strain path. Increased strain without die contact causes an increase in the surface roughness with strain paths close to plane strain exhibiting the highest roughening rate. The deformation modes of sliding, pressing, and bending cause a decrease in the surface roughness (i.e. smoothing) to occur. A first-order model is proposed to account for the surface roughness as a function of these deformation modes.     

Optimizing sequencing batch reactor (SBR) reactor operation for treatment of dairy wastewater with aerobic granular sludge

The biological wastewater treatment using aerobic granular sludge is a new and very promising method, which is predominantly used in SBR reactors which have higher volumetric conversion rates than methods with flocculent sludge. With suitable reactor operation, flocculent biomass will accumulate into globular aggregates, due to the creation of increased substrate gradients and high shearing power degrees. In the research project described in this paper dairy wastewater with a high particle load was treated with aerobic granular sludge in an SBR reactor. A dynamic mathematical model was developed describing COD and nitrogen removal as well as typical biofilm processes such as diffusion or substrate limitation in greater detail. The calibrated model was excellently able to reproduce the measuring data despite of strongly varying wastewater composition. In this paper scenario calculations with a calibrated biokinetic model were executed to evaluate the effect of different operation strategies for the granular SBR. Modeling results showed that the granules with an average diameter of 2.5 mm had an aerobic layer in between 65-95 microm. Density of the granules was 40 kgVSS/m3. Results revealed amongst others optimal operation conditions for nitrogen removal with oxygen concentrations below 5 gO2/m3. Lower oxygen concentrations led to thinner aerobic but thicker anoxic granular layers with higher nitrate removal efficiencies. Total SBR-cycle times should be in between 360-480 minutes. Reduction of the cycle time from 480 to 360 minutes with a 50% higher throughput resulted in an increase of peak nitrogen effluent concentrations by 40%. Considering biochemical processes the volumetric loading rate for dairy wastewater should be higher than 4.5 kgCOD/(m3*d). Higher COD input load with a COD-based volumetric loading rate of 9.0 kgCOD/(m3*d) nearly led to complete nitrogen removal. Under different operational conditions average nitrification rates up to 5 gNH/(m3*h) and denitrification rates up to 3.7 gNO/(m3*h) were achieved.     

Modelling the energy balance of an anaerobic digester fed with cattle manure and renewable energy crops

Knowledge of the net energy production of anaerobic fermenters is important for reliable modelling of the efficiency of anaerobic digestion processes. By using the Anaerobic Digestion Model No. 1 (ADM1) the simulation of biogas production and composition is possible. This paper shows the application and modification of ADM1 to simulate energy production of the digestion of cattle manure and renewable energy crops. The paper additionally presents an energy balance model, which enables the dynamic calculation of the net energy production. The model was applied to a pilot-scale biogas reactor. It was found in a simulation study that a continuous feeding and splitting of the reactor feed into smaller heaps do not generally have a positive effect on the net energy yield. The simulation study showed that the ratio of co-substrate to liquid manure in the inflow determines the net energy production when the inflow load is split into smaller heaps. Mathematical equations are presented to calculate the increase of biogas and methane yield for the digestion of liquid manure and lipids for different feeding intervals. Calculations of different kinds of energy losses for the pilot-scale digester showed high dynamic variations, demonstrating the significance of using a dynamic energy balance model.     

Systematic bias in job evaluation and market wages: Implications for the comparable worth debate.

Evaluated the consequences of systematic measurement errors in job evaluation and in wage distributions used as a criterion in the empirical validation of job evaluation. The way reverse regression combined with conventional regression could be used to identify systematic errors under a restrictive set of assumptions was also demonstrated. It was found that bias against female key or benchmark job wages had the generally hypothesized negative impact on predictions for female non-key job wages. However, systematic evaluation bias of female jobs does not necessarily serve to the wage disadvantage of all female jobs. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A NOTE ON NON-STATIONARITY AND CANONICAL ANALYSIS OF MULTIPLE TIME SERIES MODELS

Abstract. Box and Tiao (1977) established the correspondence between non-stationary roots and canonical correlations of an AR(1) process. In this paper, we give an alternative, more direct, proof of the correspondence and extend a special case of that result to AR( p ) processes. The usefulness of these results for multiple time series modelling is also briefly discussed.     

Hohlfaser-Membrankontaktoren zur Stickstoffrückgewinnung aus Prozesswasser einer kommunalen Kläranlage

Process water deriving from digested sludge dewatering at municipal wastewater treatment plants (WWTP) represents an additional load for the plant in terms of nitrogen. Münster WWTP is the first German plant to operate an innovative full-scale membrane contactor facility for nitrogen removal and recovery from process water. Within the scope of this study, aspects influencing the membrane performance and operation as well as utilization of the produced fertilizer are investigated. First results reveal nitrogen removal efficiencies around 85 % and a regional usability of the produced fertilizer.     

High electro-optic response in polymers doped with novel chromophores with good thermal and orientational stability

Novel chromophores designed towards the elaboration of highly electro-optic (EO) polymers have been synthesized and characterized. EO doped polymers were prepared and characterised using second harmonic generation and the Teng and Man techniques at 1.3 μm for measurements of d₃₃ and r₃₃, respectively. The measured values of r₃₃ (18 pm/V) in a polycarbonate matrix doped with 5.5% of chromophore qualify these materials for further elaboration in EO devices for optical signal processing.     

Structure-activity relationships among aromatic analogs of trail-following pheromone of subterranean termites

A series of 12 substituted (Z)-4-phenyl-3-buten-l-ol (PBO) derivatives were synthesized and evaluated for trail-following activity in five species of subterranean termites in the generaCoptotermes, Prorhinotermes, Reticulitermes, andSchedorhinotermes (Isoptera: Rhinotermitidae). The unsubstituted parent PBO was the most active for all species, and electron-withdrawing and electron-donating groups both reduced potency. Sensitivity to substitution in the ortho position suggests steric inhibition of binding by the 2-substituted analogs. Different sensitivities to these pheromone analogs were found among the five species, withR.flavipes andS. lamanianus showing the highest level of trail-following activity for the PBO analogs.Fellow of the Alfred P. Sloan Foundation (1981–85) and Camille and Henry Dreyfus Teacher-Scholar (1981–86).     

Segmentation, Indexing, and Retrieval for Environmental and Natural Sounds

We propose a method for characterizing sound activity in fixed spaces through segmentation, indexing, and retrieval of continuous audio recordings. Regarding segmentation, we present a dynamic Bayesian network (DBN) that jointly infers onsets and end times of the most prominent sound events in the space, along with an extension of the algorithm for covering large spaces with distributed microphone arrays. Each segmented sound event is indexed with a hidden Markov model (HMM) that models the distribution of example-based queries that a user would employ to retrieve the event (or similar events). In order to increase the efficiency of the retrieval search, we recursively apply a modified spectral clustering algorithm to group similar sound events based on the distance between their corresponding HMMs. We then conduct a formal user study to obtain the relevancy decisions necessary for evaluation of our retrieval algorithm on both automatically and manually segmented sound clips. Furthermore, our segmentation and retrieval algorithms are shown to be effective in both quiet indoor and noisy outdoor recording conditions.