Dehydroepiandrosterone supplementation improves predictive markers for diminished ovarian reserve: serum AMH, inhibin B and antral follicle count.

OBJECTIVE: To evaluate the effect of dehydroepiandrosterone (DHEA) supplementation on ovarian reserve by measuring markers such as antral follicle count, serum anti-Müllerian hormone (AMH) and inhibin B in patients with diminished ovarian reserve. STUDY DESIGN: This prospective study was undertaken at Dr. Zekai Tahir Burak Women's Health Research and Education Hospital, Ankara, Turkey. Forty-one patients with diminished ovarian reserve were included in the study and received supplementation with DHEA 25mg, t.i.d., for at least 6 weeks. Serum AMH, inhibin B, follicle-stimulating hormone (FSH) and oestradiol, and antral follicle count were determined before and after DHEA supplementation. Baseline ovarian reserve parameters such as antral follicle count, FSH, oestradiol, AMH, inhibin B, clinical and laboratory IVF outcomes, and pregnancy rates were studied. RESULTS: There were significant differences in day 3 FSH, oestradiol, antral follicle count, AMH and inhibin B levels before and after DHEA supplementation in all patients (p=0.001, 0.001, 0.002, 0.001 and 0.001, respectively). The study population was divided into two age groups (<35 and ≥35 years) to determine whether there was a difference in the effect of DHEA supplementation between younger and older patients with diminished ovarian reserve. Significant differences were found in all of the parameters in both study groups (p<0.05). CONCLUSIONS: DHEA supplementation is an effective option for patients with diminished ovarian reserve. Prior to assisted reproductive technology, patients with diminished ovarian reserve should be offered DHEA supplementation as an alternative to oocyte donation.

Phosphorus removal from anaerobically digested swine wastewater through struvite precipitation.

Phosphorus removal from agricultural wastewater streams is an important aspect of managing surface water quality, due to the contribution of phosphorus to eutrophication. Removal of phosphorus through struvite precipitation allows for its recovery as a potential fertilizer, and by determining the best conditions for struvite precipitation the removal process can be optimized. The effects of pH, Mg:P ratio, and time on struvite precipitation from anaerobically digested swine manure effluent were investigated. Effluent with Mg:P ratios from 1.0:1 to 1.6:1 were adjusted to pH values between 7.5 and 9.5 and left to equilibrate for 24 h. Results indicate that phosphorus removal increased with increasing pH and Mg:P ratio; the maximum phosphorus removal achieved was 80% at pH 9.0 and a Mg:P ratio of 1.6:1. The purest struvite precipitate was found at pH 7.5, with calcium carbonate and struvite precipitating at higher pH values. A continuously stirred batch of centrate was adjusted to pH 8.4 to determine the struvite formation rate constant. The rate constant was found to be 1.55 h(-1), with 17% phosphorus removal during the first 20 min. The results indicate that struvite precipitation could be a viable method of phosphorus removal from anaerobically digested swine manure.

Hydrogen limitation--a method for controlling the performance of membrane biofilm reactor for autotrophic denitrification of wastewater.

Hydrogen-driven denitrification using the fiber membrane biofilm reactor (MBfR) was evaluated for consistent operation in tertiary wastewater treatment. The possibility of controlling the process rates, as well as biofilm parameters by supplying limited amounts of electron donor (hydrogen), was tested. Limiting the hydrogen supply proved to be efficient in controlling the biofilm growth and performance of the MBfR. Denitrification rates remained unchanged for both synthetic wastewater (SWW) and real municipal wastewater (MWW) effluent as well through the fluctuations in the substrate (NO3-N) concentration. The average denitrification rates were 0.50 (+/- 0.02) g NO3-N per day per m2 for SWW and 0.59 (+/- 0.04) g NO3-N per day per m2 for MWW. Biofilm density rather than thickness was the determining factor in substrate diffusion and biofilm sloughing, ultimately determining operating stability. Limited hydrogen supply assured constant volatile solids (VS) concentration in the biofilm. It was determined that VS/TS ratio higher than 0.25 assured stable biofilm operation. Decrease of VS/TS ratio below 0.25 led to shearing of the nonbiological outer layers of the biofilm. The values of chemical oxygen demand (COD), volatile suspended solids (VSS) and total suspended solids (TSS) in the final effluent were stable and well below wastewater effluent guidelines. Substitutions of bicarbonate with gaseous carbon dioxide as the carbon source did not affect denitrification rates despite lower than optimum pH conditions.

Effect of solids retention time on the performance and biological characteristics of a membrane bioreactor.

The purpose of this study was to compare the performance of a pilot-scale membrane bioreactor (MBR) in the treatment of municipal strength wastewater at solid retention times (SRTs) ranging from 30 days to two days. Cumulative nitrogen and phosphorus mass balances resulted in closures exceeding 90% at each steady state period. Biomass production rate and biomass viability generally increased with decreasing SRT, whereas overall enzymatic activity did not change significantly at most SRTs, but was highest at the two day SRT. Nitrification decreased at two day SRT but did not fail completely. At higher SRTs, nitrification was not noticeably affected by the sludge age. Phospholipid fatty acid (PLFA) analysis showed substantially diverse biomass in the sludge at different SRTs. Different ratios of gram positive bacteria, eukaryotic organisms, and yeast cells were observed in the mixed liquor at varying SRTs. On the other hand, BIOLOG analysis indicated that the overall capacity of the biomass to degrade different carbon substrates did not change significantly at different SRTs. The concentration of metals in the MBR mixed liquor declined steadily with decreasing SRT. The MBR effluent contained negligible amounts of Fe, Zn, Mn, and Co at each condition, indicating the retention of these metals regardless of the SRT.