THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Recent advances in membrane bioreactors (MBRs): membrane fouling and membrane material.

A mini-review on membrane fouling

Membrane fouling in membrane bioreactors (MBR) normally depends on the microbial cell density and microbial population structure. A nitrifying-enriched activated sludge (NAS) was obtained in this study through particular ammonium feeding of conventional activated sludge (CAS). Next, the dominance of autotrophic nitrifier population in NAS system was checked and compared with CAS system by its high nitrification efficiency (100% vs. 43%) and low COD removal (9% vs. 65%). Furthermore, the maximum amount of N-NO3− produced from similar concentrations of ammonium in CAS and NAS systems were 6.6 mg/L and 37.5 mg/L, respectively. A filterability test also was done in the cross-flow and simple dead-end filtration systems proportionally employing different amount of NAS and CAS with a constant MLSS concentration of 2000 mg/L. NAS was twice as filterable compared to CAS. Soluble microbial products (SMP) and extracellular polymeric substance (EPS) in CAS were significantly higher than NAS system (2 and 6 mg/L for NAS vs.100 and 36 mg/L for CAS). By increasing the proportion of nitrifying bacteria, the permeation was enhanced remarkably about 2.5 folds and the operation time of MBR was approximately doubled (6–11.5 h). The results indicated that an appropriate C/N ratio can control the microbial population and help the nitrifier significantly mitigate fouling in MBR.

Effect of nitrifiers community on fouling mitigation and nitrification efficiency in a membrane bioreactor

https://www.cell.com/trends/biotechnology/pdf/S0167-7799(06)00239-3.pdf

Towards commercial production of microbial surfactants

Optimization of batch process parameters using response surface methodology for dye removal by a novel adsorbent

Response surface modeling and optimization to elucidate and analyze the effects of inoculum age and size on surfactin production

Response-surface methodology was applied to determine the effect of the fermentation process conditions, namely pH, temperature, rates of agitation and aeration, on surfactin production. The effects of the mutual interactions between these parameters were extensively studied to optimize the process conditions for the maximum production of surfactin. With a view to simultaneously reducing the number of experiments and obtaining the mutual interactions between the variables required for achieving the optimal experimental conditions, a 24 full-factorial central composite design followed by multi-stage Monte-Carlo optimization was employed for experimental design and analysis of the results. The optimum process conditions for the enhanced production of surfactin were as follows: pH = 6.755, temperature = 37.4 °C, agitation = 140 rpm and aeration = 0.75 vvm. Relative surfactin concentrations were denoted by the reciprocal of the critical micelle concentrations.

T. Swaminathan

Papers

Optimization of batch process parameters using response surface methodology for dye removal by a novel adsorbent

Response surface modeling and optimization to elucidate and analyze the effects of inoculum age and size on surfactin production

Application of response-surface methodology to evaluate the optimum environmental conditions for the enhanced production of surfactin

Effect of DO concentration on biofilm structure and membrane filterability in submerged membrane bioreactor.

Characterization of concentration and purification parameters and operating conditions for the small-scale recovery of surfactin