Simultaneous recovery of phosphorus and potassium as magnesium potassium phosphate from synthetic sewage sludge effluent.

Bench-scale experiments were performed to investigate simultaneous recovery of phosphorus and potassium from synthetic sewage sludge effluent as crystals of magnesium potassium phosphate (MPP or struvite-(K), MgKPO4·6H2O). The optimal pH of MPP formation was 11.5. A phosphorus level of at least 3 mM and K:P molar ratio over 3 were necessary to form MPP, which showed higher content rate of phosphorus and potassium in precipitate. MPP crystallization was confirmed by analysing the precipitates using a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) apparatus and an X-ray Diffractometer (XRD). Inhibition of MPP crystallization by iron and aluminium was confirmed by precipitation experiments and SEM-EDX analysis. Potassium ratio against magnesium in precipitate decreased for iron concentrations greater than over 0.2 mM and aluminium concentrations over 0.05 mM.

Deconjugation characteristics of natural estrogen conjugates by acid-catalyzed solvolysis and its application for wastewater samples.

Deconjugation reactions of natural estrogen conjugates were studied here by three different solutions of 1 M hydrochloric acid (HCl) in methanol. Estrogen sulfates could be easily deconjugated even at low temperature, while deconjugation conditions of estrogen glucuronides required a higher temperature and longer time. For 1 M HCl in methanol with 8% water, the deconjugation efficiencies of the three studied estrogen glucuronides were below 59.4% at 80 degrees C for 360 min, while the corresponding deconjugation efficiencies were above 80.6% for anhydrous HCl methanol at 80 degrees C for 210 min, which suggested trace water in the solution of 1 M HCl methanol retarded the deconjugation rates of estrogen glucuronides. On the other hand, their corresponding deconjugation rates increased with the addition of ethyl acetate, and their corresponding deconjugation efficiencies were above 86.7% at 80 degrees C for 120 min. As water is a highly polar solution, and the polarity of ethyl acetate is lower than that of methanol, this may suggest that a low polar substance would favor the reaction, while a highly polar solution would prohibit the reaction. All reactions were in pseudo first-order, and higher temperature increased the reaction rate. Finally, a GC-MS method for simultaneous analysis of free estrogens and estrogen conjugates in wastewater with acid-catalyzed solvolysis was developed, and satisfactory recovery efficiencies were obtained by spiking the standard target chemicals into the influent and effluent of one municipal wastewater treatment plant (WWTP), which demonstrated the feasibility of the developed method. Compared with enzymatic hydrolysis, the acid-catalyzed solvolysis method developed here to deconjugate estrogen conjugates is cost effective and time-saving, giving it a greater potential for use with environmental samples.

A review of phytoestrogens: their occurrence and fate in the environment.

Phytoestrogens are plant compounds with estrogenic activities. Many edible plants, some of which are common in the human diet, are rich in phytoestrogens. Almost all phytoestrogens eaten daily by people were reported partly recovered in urine or feces, which can be regarded as one of the main sources of their occurrence in municipal wastewaters. As they may act as one part of the endocrine disrupting compounds (EDCs) in water systems, some phytoestrogens have been monitored and detected in wastewater and other various environments. It is very difficult to monitor numerous unknown EDCs in complex wastewater samples, and it is helpful if some estimation of target EDCs can be done before monitoring. With this in mind, this review will: (1) summarize estrogenic activities or estrogenic potencies of phytoestrogens by different bioassays; (2) summarize daily urinary excretion rates of phytoestrogens by humans, and compare their urinary excretion rates to that of estrone, which suggests that most phytoestrogens may occur in municipal wastewaters; (3) collect and summarize published data on the occurrence and fate of phytoestrogens in various environments.

Profile and removal of endocrine disrupting chemicals by using an ER/AR competitive ligand binding assay and chemical analyses.

An estrogen receptor (ER)/androgen receptor (AR) ligand competitive binding assay (ER/AR-binding assay) and chemical analyses were used to evaluate the endocrine disrupting chemicals (EDCs) behavior of two municipal wastewater treatment plants (WWTPs) (K and S). In the influents, estrone (E1), androsterone (A), androstenedione (AD), BPA (bisphenol A), NP (nonylphenol) and daidzein (DZ) were detected in high amounts with subsequent 24 h-average concentrations of 350, 1000, 29, 1300, 3900, and 5700 ng/L in K-WWTP and of 310, 620, 59, 1600, 2600, and 8400 ng/L in S-WWTP. The estrogenic (androgenic) activity as 17beta-estradiol (E2) equivalents (EEQ) or testosterone (Te) equivalents (TEQ) was consequently 620 ng E2/L (570 ng Te/L) and 580 ng E2/L (800 ng Te/L) for the two WWTPs. The removal efficiencies of the above mentioned sole target chemicals were 51%-100% for K-WWTP and 55.6%-100% for S-WWTP. The removal efficiencies of EEQ were about 73% for both WWTPs, while the removal efficiencies of TEQ were 62.1% for K-WWTP and 98.4% for S-WWTP. In addition, chemical-derived EEQ were about 1.2%-52.4% of those by ER-binding assay for K-WWTP and the corresponding ratios were 1.3%-83.3% for S-WWTP, while chemical derived TEQ were less than 3% of values measured by the AR-binding assay for both WWTPs.

Urinary excretion rates of natural estrogens and androgens from humans, and their occurrence and fate in the environment: a review.

Endocrine disrupting compounds (EDCs) are pollutants with estrogenic or androgenic activities at very low concentrations and are emerging as a major concern for water quality. For sewage of municipal wastewater treatment plants in cities, one of the most important sources of EDCs are natural estrogens and natural androgens (NEAs) excreted from humans. Therefore, estrogenic/androgenic potencies or relative binding affinity of the NEAs were first outlined from different sources, and data of urinary excretion rates of NEAs were summarized. To evaluate their estrogenic activities, their excretion rates of estrogen equivalent (EEQ) or testosterone (T) equivalent (TEQ) were also calculated. Based on our summary, the total excretion rates of EEQ by estrone (E1), 17beta-estradiol (E2), and estriol (E3) only accounted for 66-82% of the total excretion rate of EEQ among four different groups, and the other corresponding natural estrogens contributed 18-34%, which meant that some of the other natural estrogens may also exist in wastewater with high estrogenic activities. Based on the contribution ratio of individual androgens to the total excretion rate of TEQ, five out of 12 natural androgens, T, dihydrotestosterone (DHT), androsterone (AD), 5beta-androstanediol (beta-ADL), and androstenediol (ANL) were evaluated as the priority natural androgens, which may exist in wastewater with high androgenic activities. Published data on occurrence and fate of the NEAs including natural estrogen conjugates in the environment were also summarized here.

Removal mechanisms for endocrine disrupting compounds (EDCs) in wastewater treatment - physical means, biodegradation, and chemical advanced oxidation: a review.

Endocrine disrupting compounds (EDCs) are pollutants with estrogenic or androgenic activity at very low concentrations and are emerging as a major concern for water quality. Within the past few decades, more and more target chemicals were monitored as the source of estrogenic or androgenic activity in wastewater, and great endeavors have been done on the removal of EDCs in wastewater. This article reviewed removal of EDCs from three aspects, that is, physical means, biodegradation, and chemical advanced oxidation (CAO).