Superfine Powdered Activated Carbon (S-PAC) Coupled with Microfiltration for the Removal of Trace Organics in Drinking Water Treatment

Anthropogenic contaminants - such as pharmaceuticals and personal care products - are an area of emerging concern in the treatment of drinking water. An integrated activated carbon membrane coating consisting of superfine powdered activated carbon (S-PAC) with particle size near or below one micrometer was explored to enhance removal of trace synthetic organic contaminants (SOCs) from water. S-PAC was chosen for its fast adsorption rates relative to conventionally sized PAC and atrazine was chosen as a model SOC. S-PAC and microfiltration membranes have a symbiotic relationship; membrane filtration separates S-PAC from water, while S-PAC adds capacity for a membrane process to remove soluble components. Three aspects of S-PAC in conjunction with membranes were examined, fouling by S-PAC on the membrane, effects of S-PAC production on material parameters, and modeling of S-PAC adsorption with and without a membrane. Fouling caused by carbon particles can result in marked reduction of filtration rate and an increased cost of operation. Since larger carbon particles foul less than smaller particles, while smaller carbons have faster adsorption performance, states of carbon aggregation were tested for filtration. Particles aggregated using the coagulant ferric chloride resulted in improved flux, while aluminum sulfate and polyaluminum chloride resulted in the same or worse filtration rates. A calcium chloride control showed that increased effective particle size via divalent bridging was very successful in reducing fouling. While particle size increased with conventional coagulants, the unflocculated metal precipitates likely contributed to membrane fouling. The methods of producing S-PAC determine material properties that affect both adsorption and filtration performance. In-house S-PACs - including multiple sizes of several carbon types - were prepared by wet bead milling and measured for both physical and chemical material parameters. Physical parameters, aside from particle size, did not change deterministically with milling duration, although stochastic changes were observed. Chemical measurements revealed a heavily oxidized external particle surface resulting from a high energy milling environment. Surfaces of interior pores appeared to be unaffected. Adsorption via batch kinetics and adsorption via S-PAC coating were modeled with analytical and computational models, respectively, using experimental data produced from the in-house S-PACs. The experimental data showed that removal of atrazine by S-PAC membrane coating correlated most strongly to a combination of oxygen content and the specific external surface area, while membrane fouling correlated to particle size and the specific external surface area. Batch kinetics data were modeled with the homogeneous surface diffusion model (HSDM) while membrane coating data were modeled with computational fluid dynamics (CFD). The fitted models required isotherm parameters indicative of an adsorbent with more capacity than was measured for S-PAC experimentally. Lastly, surface diffusion coefficients were neither constant nor varied with any measured material parameter. However, both model parameters correlated with overall atrazine removal, which indicates that model fits are related to performance, but it is not yet clear how they are connected

Dissolved Carbon Dioxide for Scale Removal in Reverse Osmosis

Membrane fouling is a major operational issue in reverse osmosis (RO) desalination plants. In particular, plants treating brackish groundwater can encounter troublesome inorganic scales, including carbonates, sulfates, and silicates. A novel cleaning method is proposed to remove inorganic scales from fouled RO membranes usinag dissolved CO 2 . As CO2 molecules encounter membrane foulants, the surfaces serve as nucleation sites for small bubbles to form and shear off foulants. Dissolved CO2 solutions were prepared by bubbling CO2 gas into water held in a pressure vessel. Gas dissolution was confirmed by enhanced exit velocities for water containing CO2 , due to the increase in volume from exsolution, when compared to water containing less soluble N2 . A dissolved CO2 solution was effective in removing scale from RO membranes through bubble nucleation. Membranes scaled with CaCO3 were cleaned for 10 minutes with a once-through dissolved CO2 solution of approximately pH 4.5, achieving an average 80% flux recovery. Controls were performed with other cleaning regimes to isolate effects from pH and air scouring present in CO2 cleaning. An HCl solution at pH 3 provided an average flux recovery of 79% after circulating through the system for 30 minutes, while an HCl solution at pH 4 only gave an average 20% flux recovery. Trials using N2 gas in place of CO2 only produced a 6% flux recovery on average. Lowering the pH of the N2 solution to pH 4 with HCl boosted cleaning slightly to an average 8% flux recovery. Thus, the low pH of the CO2 solution at pH 4.5 and bulk phase air scouring are minor mechanisms in scale removal. In addition, membranes scaled with calcium silicates were not cleaned using dissolved CO2 - only NaOH at pH 12 plus sodium dodecyl sulfate provided significant cleaning. Future work should be done with additional scale types to narrow in on the mechanism for cleaning by dissolved CO2

Small time deposits and the recent weakness in M2

The authors review the supply and demand side developments that may have contributed to the recent decline in small time deposits and weak M2 growth. They also consider whether M2 should be redefined to exclude small time deposits in light of the recent difficulties in interpreting the performance of M2.Bank deposits ; Money supply ; Bank loans

Recent innovations in Treasury cash management

The Treasury Tax and Loan program, a joint undertaking of the Treasury and the Federal Reserve, is designed to manage federal tax receipts and stabilize the supply of reserves in the banking system. Three recent innovations-electronic collection of business taxes, real-time investment of excess Treasury balances, and competitive bidding for Treasury deposits-have materially enhanced the ability of the two agencies to achieve these objectives.Taxation ; Tax and loan account ; Federal Reserve System

Reserves forecasting for open market operations

Bank reserves ; Open market operations

EvolvingBehavior: Towards Co-Creative Evolution of Behavior Trees for Game NPCs

To assist game developers in crafting game NPCs, we present EvolvingBehavior, a novel tool for genetic programming to evolve behavior trees in Unreal Engine 4. In an initial evaluation, we compare evolved behavior to hand-crafted trees designed by our researchers, and to randomly-grown trees, in a 3D survival game. We find that EvolvingBehavior is capable of producing behavior approaching the designer's goals in this context. Finally, we discuss implications and future avenues of exploration for co-creative game AI design tools, as well as challenges and difficulties in behavior tree evolution.Comment: 13 pages, 5 figures. Accepted for publication in Foundations of Digital Games 2022 (FDG '22

Non Equivalent: The State of Education in New York Citys Hasidic Yeshivas

Yaffed was founded to address the lack of secular education in many ultra-Orthodox schools. Tens of thousands of children attending these schools, also known as yeshivas, are being denied the education to which they are entitled under New York State law. For more than five years we have worked to educate public officials about this matter. Throughout, city and state education officials have demonstrated ignorance, disregard, and gross incompetence and in all these years have done little or nothing to improve education at these institutions.This report attempts to change that by increasing public awareness about ultra-Orthodox education.It describes the lack of secular education in many ultra-Orthodox and Hasidic yeshivas and the government inaction that has come at the expense of tens of thousands of children. It exposes the array of funding that the government doles out to yeshivas while fully aware that these schools arenot meeting standards. Finally, it sheds light on the grave consequences for the citizens of New York City and New York State were this problem to remain unchecked. We hope that the information provided here will enable readers to stand up for these children and for the proper use of their own tax dollars.After years of broken promises on the part of New York City and State education departments —after phantom investigations and reports, missed deadlines with no explanation, and promisedimprovements that never occurred — it is time the matter is addressed so that tens of thousands of current and future students at those yeshivas receive the education to which they are entitled. It is our sincere hope that this report will make that happen sooner. We invite the public to join us in demanding change

An alternative method of long lead-time tool purchases

Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2002.Includes bibliographical references (p. 132-140).by Eric W. Partlan.S.M.M.B.A

Nuclear Flow in Consistent Boltzmann Algorithm Models

We investigate the stochastic Direct Simulation Monte Carlo method (DSMC) for numerically solving the collision-term in heavy-ion transport theories of the Boltzmann-Uehling-Uhlenbeck (BUU) type. The first major modification we consider is changes in the collision rates due to excluded volume and shadowing/screening effects (Enskog theory). The second effect studied by us is the inclusion of an additional advection term. These modifications ensure a non-vanishing second virial and change the equation of state for the scattering process from that of an ideal gas to that of a hard-sphere gas. We analyse the effect of these modifications on the calculated value of directed nuclear collective flow in heavy ion collisions, and find that the flow slightly increases.Comment: 12 pages, REVTeX, figures available in PostScript from the authors upon reques