Enhanced sludge dewatering using a novel synergistic iron/peroxymonosulfate-polyacrylamide method.

In the sludge dewatering process, a formidable challenge arises due to the robust interactions between extracellular polymeric substances (EPS) and bound water. This study introduces a novel, synergistic conditioning method that combines iron (Fe2+)/peroxymonosulfate (PMS) and polyacrylamide (PAM) to significantly enhance sludge dewatering efficiency. The application of the Fe2+/PMS-PAM conditioning method led to a substantial reduction in specific filtration resistance (SFR) by 82.75% and capillary suction time (CST) by 80.44%, marking a considerable improvement in dewatering performance. Comprehensive analyses revealed that pre-oxidation with Fe2+/PMS in the Fe2+/PMS-PAM process effectively degraded EPS, facilitating the release of bound water. Subsequently, PAM enhanced the flocculation of fine sludge particles resulting from the advanced oxidation processes (AOPs). Furthermore, analysis based on the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory demonstrated shifts in interaction energies, highlighting the breakdown of energy barriers within the sludge and a transition in surface characteristics from hydrophilic (3.79 mJ m-2) to hydrophobic (-61.86 mJ m-2). This shift promoted the spontaneous aggregation of sludge particles. The innovative use of the Flory-Huggins theory provided insights into the sludge filtration mechanism from a chemical potential perspective, linking these changes to SFR. The introduction of Fe2+/PMS-PAM conditioning disrupted the uniformity of the EPS-formed gel layer, significantly reducing the chemical potential difference between the permeate and the water in the gel layer, leading to a lower SFR and enhanced dewatering performance. This thermodynamic approach significantly enhances our understanding of sludge dewatering and conditioning. These findings represent a paradigm shift, offering innovative strategies for sludge treatment and expanding our comprehension of dewatering and conditioning techniques.

Novel combination of iron-carbon composite and Fenton oxidation processes for high-concentration antibiotic wastewater treatment.

The research presented herein explores the development of a novel iron-carbon composite, designed specifically for the improved treatment of high-concentration antibiotic wastewater. Employing a nitrogen-shielded thermal calcination approach, the investigation utilizes a blend of reductive iron powder, activated carbon, bentonite, copper powder, manganese dioxide, and ferric oxide to formulate an efficient iron-carbon composite. The oxygen exclusion process in iron-carbon particles results in distinctive electrochemical cells formation, markedly enhancing wastewater degradation efficiency. Iron-carbon micro-electrolysis not only boosts the biochemical degradability of concentrated antibiotic wastewater but also mitigates acute biological toxicity. In response to the increased Fe2+ levels found in micro-electrolysis wastewater, this research incorporates Fenton oxidation for advanced treatment of the micro-electrolysis byproducts. Through the synergistic application of iron-carbon micro-electrolysis and Fenton oxidation, this research accomplishes a significant decrease in the initial COD levels of high-concentration antibiotic wastewater, reducing them from 90,000 mg/L to about 30,000 mg/L, thus achieving an impressive removal efficiency of 66.9%. This integrated methodology effectively reduces the pollutant load, and the recycling of Fe2+ in the Fenton process additionally contributes to the reduction in both the volume and cost associated with solid waste treatment. This research underscores the considerable potential of the iron-carbon composite material in efficiently managing high-concentration antibiotic wastewater, thereby making a notable contribution to the field of environmental science.

[Clinical efficacy and safety of uterine artery chemoembolization in abnormal placental implantation complicated with postpartum hemorrhage].

OBJECTIVE: To investigate the safety and clinical efficacy of uterime artery chemoembolization in postpartum hemorrhage (PPH) caused by abnormal placental implantation. METHODS: Between December 2006 and September 2009, there were 23 cases of abnormal placental implantation with PPH in our hospital, among which 9 presented with continuous small amount of vaginal bleeding and 14 with acute excessive bleeding. The average bleeding time was (8+/-6) d and the mean blood loss was (980+/-660) ml. Abnormal placental implantation was confirmed by color Doppler ultrasound (CD-US) in all cases, the internal iliac artery angiography was performed to identify the uterine artery and bilateral uterine artery chemoembolization (UACE) with methotrexate (MTX) and gelfoam particles to the distal end of uterine artery was conducted after. CD-US rechecked all patients within 48 h after UACE and those patients with blurred margins between placenta and uterus and abnormal blood flow (>1 cmx1 cm) received ultrasonic-guided per vagina MTX multipoint injections. All cases were followed up for 3-26 months (average 12 months) to observe vaginal bleeding, placenta tissue discharge, serum human chorionic gonadotropin (hCG), uterine involution, menses, and side-effects or complications. RESULTS: (1) Curative effect: These 23 cases underwent 24 procedures of UACE successfully and vaginal bleeding ceased at an average of (3.5+/-1.3) min after UACE. Reduced blood flow in the placental implantation area was detected under CD-US after UACE. Among the 23 patients, wterine curettage was required in 16 cases due to retained placenta tissues with the mean blood loss of (40+/-28) ml during the operation, 2 underwent subtotal hysterectomy and confirmed to be placenta percreta by pathology examination, and placenta tissues were spontaneously discharged completely in 5 cases. Totally, 91% of the patients (21/23) reserved their uterus. (2) FOLLOW-UP: the serum hCG reduced to normal within 1-13 d after the placenta tissue were evacuated. Regular menstruation returned within 2-3 months in those patients who reserved uterus and normal size uterus was found under sonography at 3 months. No severe complication was reported except for some post embolization syndrome, such as pelvic pain or fever. CONCLUSIONS: UACE, combined with ultrasonic-guided transvaginal MTX injection, is a safe, minimal invasive and quick hemostatic procedure in treatment of abnormal placental implantation with PPH, and allows the preservation of uterus possible. CD-US is helpful in evaluation of the blood flow changes before and after UACE in abnormal placental implantation patients.