Search

In this paper, short-term exposure experiments with different ZVI concentrations were conducted to research the effects of ZVI adding on the anaerobic system for treating swine wastewater. Increasing the ZVI dose had a stimulatory effect on COD removal and CH 4 production possibly due to a higher corrosion-induced H 2 and dissolved ferrous ions, which could stimulate the methanogenesis and thus the biodegradation. In addition, the abiotic corrosion reactions such as flocculation, adsorption and precipitation were inevitable to removal some suspended COD. However, high ZVI doses had a potential risk on microorganism due to the present of large numbers of solid iron species in sludge, which likely encapsulated the cells and even damaged the cellular structure. Taken as a whole, the most enhancing effect induced by ZVI was observed at the r ZVI/VSS of 2.63, and the maximum efficiency of per ZVI adding occurred at the r ZVI/VSS of 0.74. But the ZVI concentration of 50 g/L (the r ZVI/VSS was 5.26) was proved too high to facilitate microorganism activity, considering the higher LDH leakage and lower intracellular ATP level than the only sludge system. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOFs act as dual-functional adsorbents and electrocatalysts for the removal of PPCPs. • Real active sites of MOFs are pinpointed using in-situ electrochemical methods. • Fe-MOFs exhibit high efficacy and stability in practical wastewater treatment. Pharmaceuticals and personal care products (PPCPs) pose a significant wastewater pollution concern. While electrochemical oxidation is promising, it struggles with slow mass transfer. To address this, we propose a novel strategy utilizing bifunctional metal–organic frameworks (MOFs) that couple an adsorbent with an electrocatalyst. The real active sites within iron-based MOFs responsible for the adsorption of PPCPs are MIL-101(Fe) molecules, while the in-situ formed active sites, α -FeOOH, accelerate the charge transfer under bias, contributing to the electrooxidation of PPCPs. The rapid destruction of adsorbed organics on the dual-functional electrode surface enables to release adsorption sites. This, in turn, paves the way for fast and efficient re-adsorption of PPCPs molecules, consequently promoting mass transfer. Iron-based MOFs exhibit excellent adsorption capacity (∼60 mg g−1 for sulfosalicylic acid, ∼15 mg g−1 for acetaminophen) and electrooxidation ability (94 % removal in 2 h, 31.2 kWh kg−1 COD) with good stability in realistic pharmaceutical wastewater treatment. This study offers a novel strategy for removing PPCPs using molecular electrocatalysts and provides new insights for designing and constructing MOFs for refractory wastewater treatment. [ABSTRACT FROM AUTHOR]

• A cocatalyst loading strategy is proposed for wastewater electrochemical treatment. • The cocatalyst NiOOH accelerates the charge transfer, thus promoting water oxidation. • The increased reactive oxygen species promote the electrooxidation of organics. • The electrode shows great promise for pharmaceutical wastewater treatment. Acetaminophen (APAP), a common pharmaceutical and personal care product, is highly toxic and resistant to conventional wastewater treatment. Electrochemical oxidation is a promising technique for removing pharmaceuticals and personal care products (PPCPs), and the Ti-doped α -Fe 2 O 3 electrode is a low-cost alternative to noble-metal electrocatalysts. Herein, we present a novel cocatalyst loading strategy to enhance the electrocatalytic ability of the electrodes by loading a cocatalyst, NiOOH, by electrodeposition. The cocatalyst leads to a higher potential drop (97.7%) on the Helmholtz layer than the bare one (80.5%) and accelerates the charge transfer by ten. The increased production of reactive oxygen species during water activation further facilitates the electrooxidation of APAP, resulting in a threefold increase in removal rate and a twofold increase in Faraday efficiency. Additionally, the obtained NiOOH/Ti-Fe 2 O 3 electrode shows excellent ability (100% APAP removal in 2 h) and stability (removal efficiency greater than 94% after ten cycles) for pharmaceutical wastewater treatment containing APAP. These findings provide a novel and generalized strategy for enhancing the electrocatalytic ability of Ti-doped α -Fe 2 O 3 electrodes and offer valuable guidelines for exploring efficient and economic electrocatalysts for refractory wastewater treatment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Anaerobic membrane bioreactor was applied to treat bamboo industry wastewater. [•] N2 flushing was employed as the membrane fouling control method. [•] Influence of HRT on the system performance and membrane cleaning was evaluated. [•] Major organic compounds in raw and treated wastewater were analyzed by GC–MS. [ABSTRACT FROM AUTHOR]

Abstract: Dilemmas like water shortage, rapid industrialization, growing human population and related issues have seriously affected human health and environmental sustainability. For conservation and sustainable use of our water resources, innovative methods for wastewater treatment are continuously being explored. Advance Oxidation Processes (AOPs) show a promising approach to meet specific objectives of municipal wastewater treatment (MWW). The MWW samples were pretreated with Al2(SO4)4·8H2O (Alum) at different doses 4, 8, 12–50mg/L to enhance the sedimentation. The maximum COD removal was observed at alum treatments in range of 28–32mg/L without increasing total dissolved solids (TDS). TDS were found to increase when the alum dose was increased from 32–40mg/L. In the present study, the optimum alum dose of 30mg/L for 3h of sedimentation and subsequent integrated H2O2/UV treatment was applied (using 2.5mL/L of 40% waste H2O2 and 35% fresh H2O2 separately). Organic and inorganic pollutants, contributing towards chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity and total dissolved solids were degraded by H2O2/UV. About 93% COD, 90% BOD and 83% turbidity reduction occurred when 40% waste H2O2 was used. When using fresh H2O2, 63% COD, 68% BOD and 86% turbidity reduction was detected. Complete disinfection of coliform bacteria occurred by using 40% H2O2/UV. The most interesting part of this research was to compare the effectiveness of waste H2O2 with fresh H2O2. Waste H2O2 generated from an industrial process of disinfection was found more effective in the treatment of MWW than fresh 35% H2O2. [Copyright &y& Elsevier]

Abstract: Car wash wastewater (CWW) contains petroleum, hydrofluoric acid, ammonium bifluoride products, paint residues, rubber, phosphates, oil, grease and volatile organic compounds (VOCs). The present study dealt with various investigations conducted for the treatment of CWW. A treatment system of 5L capacity was designed in the laboratory. Due to high load of oil and grease, CWW was aerated and scum was removed. Alum was used as coagulant in primary treatment which resulted 93% and 97% reduction in COD and turbidity. During secondary treatment CWW was further treated with waste hydrogen peroxide which resulted in further 71% and 83% reduction in COD and turbidity, respectively. Other desirable changes were also observed in pH, total dissolved solids (TDS), conductivity and dissolved oxygen contents. It was concluded that designed system could be effectively used to treat carwash wastewater that could be reused in the same station. [Copyright &y& Elsevier]

Biotechnology can be used to assess the well being of ecosystems, transform pollutants into benign substances, generate biodegradable materials from renewable sources, and develop environmentally safe manufacturing and disposal processes. Simultaneous elimination of sulfide and nitrite from synthetic wastewaters was investigated using a bioreactor. A laboratory scale anoxic sulfide-oxidizing (ASO) reactor was operated for 135 days to evaluate the potential for volumetric loading rates, effect of hydraulic retention time (HRT) and substrate concentration on the process performance. The maximal sulfide and nitrite removal rates were achieved to be 13.82 and 16.311kg/(m3 day), respectively, at 0.10 day HRT. The process can endure high sulfide concentrations, as the sulfide removal percentage always remained higher than 88.97% with influent concentration up to 1920mg/L. Incomplete sulfide oxidation took place due to lower consumed nitrite to sulfide ratios of 0.93. It also tolerated high nitrite concentration up to 2265.25mg/L. The potential achieved by decreasing HRT at fixed substrate concentration is higher than that by increasing substrate concentration at fixed HRT. The process can bear short HRT of 0.10 day but careful operation is needed. Nitrite conversion was more sensitive to HRT than sulfide conversion when HRT was decreased from 1.50 to 0.08 day. Stoichiometric analyses and results of batch experiments show that major part of sulfide (89–90%) was reduced by nitrite while some autooxidation (10–11%) was resulted from presence of small quantities of dissolved oxygen in the influent wastewater. There was ammonia amassing in considerably high amounts in the bioreactor when the influent nitrite concentration reached above 2265.25mg/L. High ammonia concentrations (200–550mg/L) in the bioreactor contributed towards the overall inhibition of the process. Present biotechnology exhibits practical value with a high potential for simultaneous removal of nitrite and sulfide from concentrated wastewaters at shorter HRT. [Copyright &y& Elsevier]