ABSTRACT
Electroplating sludge was a hazardous waste comprised of heavy metals and other Fe/Al/Ca/Si impurities, and produced massively in surface treatment industry. In the past, it was commonly purified via hydrometallurgy, chlorination and reduction calcination routes, but also blended as additive in rotary kiln, to stabilize the heavy metals in geopolymer. Herein, an alternative strategy was developed to treat a real electroplating sludge for recycling magnetic Zn-rich spinel and stabilizing Zn in calcium metasilicate glass via a facile pyrometallurgy route with the blending of emulsion mud and coal ash. The sludge contained 35.6% Zn and 0.54% Cr and then was blended with 50% emulsion mud. After calcination at 1200 °C, the product was highly dispersed, whilst octahedral ZnAlFeO4 spinel with Zn content of 40.0% were formed and separated by using magnet, in accordance with the recycling efficiency of 51.2% Zn from the electroplating sludge. But after calcination at 1400 °C, the gypsum in emulsion mud was decomposed as CaO and accelerated the dissolution of Si-bearing substance as calcium metasilicate glass for covering ZnAlFeO4 spinel, resulting in the Zn leaching of 1568 mg/L. By adding 50% Si-rich coal ash in the calcination system, more calcium metasilicate glass were generated, and then the Zn concentration in the toxic leaching test was only 12.09 mg/L. During the calcination, Cr showed similar performance to Al/Fe and involved in the spinel formation. This provided a new route to recycle Zn from Zn-rich electroplating sludge and to solidify heavy metals via calcium metasilicate glass route.
Subject(s)
Metals, Heavy , Sewage , Sewage/analysis , Coal Ash , Calcium , Electroplating , EmulsionsABSTRACT
Cr/Fe-bearing sludge is a hazardous solid waste, produced at mass production in smelting, plating and surface finishing industries. Such waste is commonly treated by chemical detoxification and safety landfill, whereas only a few Cr-rich sludge is recycled as a tanning reagent. In this study, a novel route was developed to recycle Cr/Fe-bearing sludge as erdite-bearing flocculant for wastewater treatment. Results showed that two sludges were irregular aggregates, one of which contained 1.6 wt.% Cr (short for LS) and the other contained 4.2 wt.% Cr (HS). After hydrothermal treatment, stable Cr(III)/S-bearing product was formed from the Cr(VI) reduction in the sludges. Conversely, erdite was generated in nanorod form with diameter and length of 200 nm and 0.5-1 µm from LS, respectively, whereas grew radially to 1.5-2.5 µm for HS. The two erdite-bearing products were spontaneously hydrolysed to Fe/S-bearing flocs and showed similar performance in the treatment of real electroplating effluent with 91.55, 1.94 and 0.25 mg/L of Zn, Ni and Cr, respectively. For instance, by adding 1 g/L product of LS, the release of Cr from the products did not occur, and the residual Zn, Ni and Cr in the effluent was 0.25, 0.65 and 0.17 mg/L, respectively, which met the discharge standard of the electroplating industry. With the two converted products, the residual Zn/Ni/Cr concentrations were apparently lower than those of the raw sludges and other common reagents (e.g. polymeric ferric sulphate, activated carbon and diatomite). Thus, such erdite-bearing products could serve as a flocculant and then be applied in electroplating wastewater treatment.
ABSTRACT
Objective:To investigate the risk factors for early complications after laparoscopy-assisted gastrectomy in patients with gastric cancer.Methods:The retrospective case-control study was conducted. The clinicopathological data of 196 patients who underwent laparos-copy-assisted radical gastrectomy at Peking Union Medical College Hospital from March 2016 to March 2019 were collected. There were 144 males and 52 females, aged (61±10)years. Observation indicators: (1) early complications after laparoscopy-assisted radical gastrectomy and treatment; (2) analysis of risk factors for early complications after laparoscopy-assisted radical gastrectomy.Measurement data with normal distribution were represented as Mean± SD, and measurement data with skewed distribution were represented as M( P25,P75). Count data were represented as absolute numbers. Univariate analysis was conducted using the t test, Mann-Whitney U test or chi-square test. Multivariate analysis was conducted using the Logistic regressional model. Results:(1) Early complications after laparoscopy-assisted radical gastrectomy and treatment: 51 of 196 patients had early postoperative complications, including 7 cases of grade Ⅰ according to Clavien-Dindo classi-fication system, 32 cases of grade Ⅱ, 9 cases of grade Ⅲa, 3 cases of grade Ⅲb. There was no grade Ⅳ or Ⅴ complication. There were 25 cases with abdominal complications, 7 cases with thoracic complications, 3 cases with internal/catheter related complications and 16 cases with other unclassified complications. All patients with complications were improved after symptomatic and supportive treatments. (2) Analysis of risk factors for early complications after laparoscopy-assisted radical gastrectomy: results of univariate analysis showed that the lymphocyte count, neutrophil-to-lymphocyte ratio, radiotherapy, operation time, volume of intraoperative blood loss, T stage, lymph node metastasis were related factors for early complications after laparoscopy-assisted radical gastrectomy in patients with gastric cancer ( Z=?2.048, χ2=6.385, 4.168, 8.068, 6.336, 12.497, 7.522, P<0.05). Results of multivariate analysis showed that the neutrophil/lymphocyte ratio ≥1.96, operation time ≥222 minutes, and lymph node metastasis were independent risk factors for early complica-tions after laparoscopy-assisted radical gastrectomy in patients with gastric cancer ( odds ratio=2.279, 2.245, 2.226, 95% confidence interval as 1.149-4.519, 1.116-4.517, 1.125-4.402, P<0.05). Conclusions:The abdominal complications are the most common early complications after laparoscopy-assisted radical gastrectomy. The neutrophil-to-lymphocyte ratio ≥1.96, operation time ≥222 minutes, and lymph node metastasis are independent risk factors for early complications after laparoscopy-assisted radical gastrectomy in patients with gastric cancer.
