Hydrometallurgical processes for heavy metals recovery from industrial sludges

Hydrometallurgical approaches have been successfully employed for metal separation and recovery from various types of waste materials. Therefore, hydrometallurgy is a promising technology for metal recovery and the removal of potentially toxic heavy metals found in industrial sludge. However, a comprehensive review that focuses on the heavy metal recovery from industrial sludge using hydrometallurgical approaches has not been conducted in the recent past. The present review discusses the capacity of hydrometallurgical techniques in recovering heavy metals sourced from different types of industrial sludges, highlighting recent scientific findings. Hydrometallurgical approaches primarily consist of three process stages: metal dissolution, concentration and purification, and metal recovery. The chemical characteristics of industrial sludge, including the type, concentration and speciation of heavy metals, directly impact selection of the best recovery method. Solvent extraction, ion-exchange, and adsorption are the major techniques employed in concentration and purification, whereas electrodeposition and precipitation are the main methods used in metals recovery. Future research should focus on the development of more efficient and environmentally-friendly methods for metal dissolution from industrial sludges contaminated with multiple metals, while increasing selectivity and energy use efficiency in the concentration and purification, and recovery steps

За кадры. 1980. № 31 (2255)

Первое место - нашей газетеЧитатель и газета / [беседа с] В. Попова ; [беседа с] М. В. Самойлова ; [беседа с] Л. Жирникова ; [беседа с] Л. Ф. Ковалева ; [беседа с] Л. И. КиселевК нашим общественным корреспондентамИным газета - бумажица… / Г. ЮровБоевые помощники / В. ФинниковаОбъявляется благодарностьЗвучащее слово. 7 мая - День радио / Г. ГалкинаВклад НТО / Л. М. АнаньевНарушители наказаны / А. Кузьмин, А. ЗаворинЭкологическая подготовка студентов / В. ФедоровЦарь сибирских лесов / И. ЗыряновЗа безотказную технологию / Л. Молодежников, А. МелешкоМесячник по охране рыбных богатств / В. ЕрохинаПером и фотокамерой / Р. Горска

The potential of biochar for reducing the negative effects of soil contamination on the phytochemical properties and heavy metal accumulation in wheat grain

The food industry faces the problem of soil contamination and consequently the deterioration of the quality of plant products. Here, we present a study on evaluation of the effect of fertilization with sewage sludge (SL) with varying, rates of biochar (BC 2.5, 5 and 10% of DW) on yield quality and the accumulation of heavy metals in wheat grains. The greatest grain yield with the highest content of protein and gluten as well as the highest total content of phenols and flavonoids, was obtained when SL+5%BC fertilization was applied. The addition of 5%BC and 10%BC to SL resulted in the greatest increase in the antioxidant capacity of grain. Among phenolic acids, syringic acid was found in the largest amount in grain in the SL+2.5%BC treatment. A significant decrease in Pb accumulation in wheat grain after application of SL+5%BC and a successive decrease in Al content with increasing BC addition were observed. To increase the quality of wheat grains and to reduce the bioaccumulation of harmful elements after the application of biochar to the soil is important in the context of food safety and health of humans especially in food production on acidic and/or contaminated soils

Physicochemical Characteristics of Biochar from Waste Cricket Chitin (Acheta domesticus)

The properties of biochar (BC) from crustacean chitin are relatively well understood, while there are few studies on BC from insect chitin. This study presents the characterization and phytotoxic assessment of BC produced from crickets and cricket chitin. Cricket powder (BCCR) and cricket chitin (BCCH) were pyrolyzed at 500 °C and 700 °C. Physicochemical characteristics, N ad-/desorption, FTIR, were examined. SEM images were also performed. Regardless of the pyrolysis temperature, biochars were characterized by a densely “packed” solid surface/monolithic type with a non-porous structure (0.05–0.22 m2/g) and high content of N (9.4–11.8%). BCCHs showed a higher pH (12.2–12.4) compared to BCCR (8.7–10.8). Based on the XRD analysis, BCs were characterized by an amorphous carbon turbostratic structure and a randomly oriented graphitic-like micro-crystallite structure. FTIR spectra of BCs confirmed the presence of various O2 and N-functional groups on the BC surface. BCCHs added to soil at rates from 0.5 to 1.5% significantly reduced the germination of Lepidium sativum. Stimulation of root elongation was also observed in the case of BCCR500 1.0% and BCCR700 1.5%. Thermal degradation of cricket powder and cricket chitin promotes the formation of organic N-containing heterocyclic rings, which lead to the production of N-doped carbons with potential uses in energy storage and the contaminations sorption