Tracking influent inorganic suspended solids through wastewater treatment plants.

From an experimental and theoretical investigation of the continuity of influent inorganic suspended solids (ISS) along the links connecting the primary settling tank (PST), fully aerobic or N removal activated sludge (AS) and anaerobic and aerobic sludge digestion unit operations, it was found that the influent wastewater (fixed) ISS concentration is conserved through primary sludge anaerobic digestion, activated sludge and aerobic digestion unit operations. However, the measured ISS flux at different stages through a series of wastewater treatment plant (WWTP) unit operations is not equal to the influent ISS flux, because the ordinary heterotrophic organisms (OHO) biomass contributes to the ISS flux by differing amounts depending on the active fraction of the VSS solids at that stage.     

Relations of social goal pursuit to social acceptance, classroom behavior, and perceived social support.

Relations of social goal pursuit to (1) social acceptance by teachers and peers, (2) prosocial and irresponsible classroom behavior, and (3) perceived support from teachers and peers were examined. Ss were 475 6th and 7th graders. Students' pursuit of academic prosocial goals (to help classmates with academic problems) was related positively to peer acceptance. Pursuit of academic responsibility goals (adhering to classroom rules) was related negatively to peer acceptance but positively to teacher acceptance. These findings reflected in part, significant relations between social goal pursuit and displays of social behavior. Perceived support from teachers and peers was also related positively to social goal pursuit, although findings differed as a function of type and source of support. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anoxic growth of phosphate-accumulating organisms (PAOs) in biological nutrient removal activated sludge systems

In this paper, research on the growth performance of phosphate-accumulating organisms (PAOs) was conducted based on literature and experimental investigations on biological nutrient removal (BNR) activated sludge (BNRAS) systems. The research aims at presenting the occurrence of denitrifying PAOs (DPAOs), abstracting information on the kinetics and stoichiometry of PAOs under anoxic conditions and determining the conditions that stimulate the PAO growth under anoxic conditions. The research results indicate that the PAOs are capable of utilizing nitrate as electron acceptor instead of oxygen in BNRAS systems, particularly in external nitrification BNRAS (ENBNRAS) systems. However, the growth yield of PAOs under anoxic conditions should be reduced to about 70% of that under aerobic conditions, and further the stoichiometric coefficient for anoxic P uptake per PHB COD utilized should be reduced to about 80% of that under aerobic conditions as the DPAOs show a significantly lower BEPR performance and use the influent RBCOD less "efficiently" compared with aerobic PAOs (APAOs). The research results also indicate that the major factor influencing the occurrence of DPAOs and associated anoxic P uptake is the nitrate load into the anoxic reactor, i.e. the nitrate load should be large enough or exceeds the denitrification potential of ordinary heterotrophic organisms (OHOs), i.e. non-PAO organisms in the anoxic reactor to stimulate DPAOs in the system as the specific denitrification rate of OHOs (K'2 OHO) is significantly larger than that of PAOs (K'2 PAO). In terms of this competition, if the nitrate load into the main anoxic reactor is less than the denitrification potential of OHOs, then the OHOs will outcompete PAOs for using the limited nitrate, while if the nitrate load in the main anoxic reactor exceeds the denitrification potential of OHOs, then the PAOs would have opportunities to use the "excess" nitrate and so develop in the system. The other factors that influence DPAOs include the system aerobic mass fraction, sequence of reactors and frequency of sludge alternation between the aerobic and anoxic states. Although it does appear that these factors above may significantly influence the fraction of DPAOs (etaG), the quantitative relationship between these factors and etaG is not known, and the experimental observations indicate that this will be system-specific, and require calibration for each situation.     

A predictive model for the reactor inorganic suspended solids concentration in activated sludge systems

A simple predictive model for the activated sludge reactor inorganic suspended solids (ISS) concentration (excluding that from chemical precipitant dosing) is presented. It is based on the accumulation of influent ISS in the reactor and an ordinary heterotrophic organism (OHO) ISS content (fiOHO) of 0.15 mg ISS/mg OHO organic (volatile) suspended solids (VSS) and a variable phosphate accumulating organism (PAO) ISS content (fiPAO) proportional to their P content (fXBGP). Organism ISS content is conceptualized as the uptake of dissolved inorganic solids by active organisms, which when dried in the total suspended solids (TSS) test procedure, precipitate and manifest as ISS. The model is validated with data from 22 investigations conducted over the past 15 years on 30 aerobic and anoxic-aerobic nitrification-denitrification (ND) systems and 18 anaerobic-anoxic-aerobic ND biological excess P removal (BEPR) systems variously fed artificial and real wastewater, and operated from 3 to 20 days sludge age. The predicted reactor VSS/TSS ratio reflects the observed relative sensitivity to sludge age, which is low, and to BEPR, which is high. To use the model for design, two parameters need to be known: (1) the influent ISS concentration, which is not commonly measured in wastewater characterization analyses and (2) the P content of PAOs (fXBGP), which can vary considerably depending on the extent of anoxic P uptake BEPR that takes place in the system. Some guidance on the measurement of influent ISS concentration and selection of the PAO P content to calculate the mixed liquor VSS/TSS ratio for design is given.     

Comparison of Rat Hepatic Cholesterol Biosynthesis During Skim Milk Versus Whey Permeate Ingestion

Whey permeate is an ultrafiltrate of whey that is devoid of protein but contains lactose, salts, and other soluble low molecular weight compounds. These experiments compared cholesterol concentrations of blood plasma, hepatic lipids, and hepatic cholesterol biosynthesis of rats ingesting skim milk powder versus whey permeate powder. Groups of young male rats weighing 90 to 92 g were fed a casein-based diet into which skim milk powder or whey permeate powder was incorporated isocalorically. No effects of skim milk or whey permeate on plasma cholesterol concentrations were observed at any time during 5-wk of feeding. However, 3-hydroxy-3-methylglutaryl coenzyme A reductase activity was increased by either skim milk or whey permeate feeding. Hepatic cholesterol, triglyceride, and phospholipid concentrations at wk 5 were unchanged. Plasma and hepatic cholesterol responses of rats to whey permeate ingestion are similar to those that occur with skim milk consumption, and plasma and hepatic cholesterol concentrations do not reflect necessarily an increase in hepatic cholesterol biosynthesis.     

The effect of residual ammonia concentration under aerobic conditions on the growth of Microthrix parvicella in biological nutrient removal plants

It is demonstrated with two parallel single reactor intermittently aerated nitrification denitrification systems fed municipal wastewater as influent, that Microthrix parvicella bulking can be stimulated and cured by manipulating the ammonia concentration in the aerobic period (by inhibiting the nitrifiers) to high and low values respectively. The proliferation or not of M. parvicella is hypothesized to be due to their requirement for ammonia as a nitrogen source for growth. In terms of this hypothesis, if nitrification is rapid and complete, ammonia is not freely available and will limit M. parvicella growth. If nitrification is not complete for whatever reason, ammonia is available for the growth of the slow growing M. parvicella, enabling their proliferation to cause a bulking sludge. This hypothesis does not overturn or replace the anoxic-aerobic (AA, or low Food/Microorganism, F/M, ratio) filament bulking hypothesis of Casey et al. (Water SA 25(4) (1999) 425) but appears to be additional to it. Future research will focus on determining how elements of both hypotheses superimpose on the conditions in BNR systems, to produce an AA filament bulking sludge or not.     

Gender-based emotional stereotyping.

Previous research documents that mental health professionals' attitudes reflect the general public's stereotype of women as hyperemotional. This article reports the results of 6 studies exploring the existence of a complementary stereotype of men as hypoemotional. As predicted, counselors and college students consistently stereotyped men as hypoemotional (all ps?p?     

Adolescent classroom goals, standards for performance, and academic achievement: An interactionist perspective.

In the 1st study, correlational results from 203 high school students suggest that achievement, as indexed by grade point average (GPA), is positively related to efforts to be a successful student, be dependable and responsible, understand things, do one's very best, and get things done on time, and negatively related to trying to have fun. Student GPAs were also related to the number of goals and the unique sets of goals that students try to achieve. In the 2nd study, with a subsample of 107 students, the motivational characteristics of students that predicted GPAs did not predict Scholastic Aptitude Test (SAT) scores. Findings of the 1st study suggest the potential relevance of motivation to achieve socially prescribed as well as cognitive outcomes for explaining academic performance in the classroom. The importance of studying motivation–performance relationships within context is suggested by the fact that the findings of Study 1 were not replicated when nonclassroom evaluations of performance were used as indices of academic achievement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conflict in families of adolescents: The impact on cohesion and power structures.

Investigated 3 characteristics (locus, content, and frequency) of conflict (CF) in families of adolescents. Ss were 134 parents and 170 early (mean age 11.5 yrs), 109 middle (mean age 16.3 yrs), and 47 late (mean age 18.7 yrs) adolescents. Ss reported family CF on T. M. Gehring and S. S. Feldman's (see record 1989-14119-001) Family System Test and in an interview. CF in marital (MADs) and parent–adolescent dyads (PADs) was frequently reported. Across adolescence, reports of PAD CF increased, especially those related to autonomy. CF decreased cohesion and changed power relations in the representations of family structure. CF in the MAD was related to decreased cohesion and increased cross-generational coalitions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)