Search results for "liete"
showing 10 items of 31 documents
To incinerate or not? - Effects of incineration on the concentrations of heavy metals and leaching efficiency of post-precipitated sewage sludge (RAV…
2020
The major element and heavy metal concentrations of post-precipitated sewage sludge (PPS) and its ash residue (PPA) were determined using microwave digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS). To the best of our knowledge, this has not been previously done. In both PPS and PPA the heavy metal concentrations were clearly below the average concentrations than those encountered in sewage sludge in Europe. The leaching efficiency of the metal (Al/ Fe) used as a precipitation agent from post-precipitated sludge and its ash residue with phosphoric acid was also investigated with previously optimized leaching conditions. T…
Brønsted and Lewis acid catalyzed conversion of pulp industry waste biomass to levulinic acid
2019
Enormous amounts of fiber sludge are generated annually by the pulp industry as a by-product. As a cellulose-rich material, its current usage, mainly as fuel, is inefficient from a material efficiency point of view. This work studied the utilization of fiber sludge from a Finnish and a Swedish pulp mill as a potential feedstock to produce levulinic acid, a valuable platform chemical. The conversion experiments of fiber sludge to levulinic acid were performed in a microwave reactor with a mixture of H2SO4 and Lewis acid as the catalyst. The reaction conditions, which included reaction time and temperature as well as the H2SO4 and Lewis acid concentrations, were studied in detail. The highest…
A preliminary study on the ecotoxic potency of wastewater treatment plant sludge combining passive sampling and bioassays.
2021
Highlights • The passive samplers collected bioavail able and bioaccessible chemicals from the WWTP sludge samples. • The sampler extracts were acutely and chronically toxic to water flea. • The sampler extracts were cytotoxic and genotoxic. • The sludge treatment such as composting and digesting diminished the toxicity. • Effect-based methods should be part of the risk assessment of sludge recycling. Sewage sludge is an inevitable byproduct produced in wastewater treatment. Reusing nutrient-rich sludge will diminish the amount of waste ending in soil dumping areas and will promote circular economy. However, during sewage treatment process, several potentially harmful organic chemicals are …
Optimizing the H3PO4 leaching conditions of post-precipitated sewage sludge using response surface methodology
2018
The leaching procedure of post-precipitated aluminium phosphate sludge with dilute phosphoric acid was developed. The leaching offers a route to recover both critical phosphorous from sewage sludge and the metal used in precipitation. Using phosphoric acid as leaching solution makes it possible to continue the recovery process without the need to remove chloride or sulfate anions. The optimization of the leaching was based on experimental three-level-four-variable central composite face-centered design. The four variables included were acid concentration, volume of acid, temperature and time of leaching. The leaching was conducted for dewatered and water-containing sludge (total solid conte…
Co-digestion of energy crops and industrial confectionery by-products with cow manure: batch-scale and farm-scale evaluation.
2002
The possible co-digestion of energy crops and industrial confectionery by-products with cow manure was evaluated firstly, through long-term batch experiments and secondly, in a farm-scale digester. In batch assays, digestion with mesophilically digested cow manure as inoculum resulted in specific methane yields (m3 kg−1 VSadded waste) of 0.35 for grass hay (particle size <1.0 cm); 0.26 for oats (0.5 cm) and 0.21 for clover (2.0 cm) harvested at vegetative stage and 0.14 (2.0 cm) for clover harvested at flowering stage. Specific methane yields (m3 kg−1 VSadded waste) for confectionery by-products were 0.37 for chocolate, 0.39 for black candy and 0.32 for confectionery raw material. Ou…
To make room or not to make room: clients’ narratives about exclusion and inclusion of spirituality in family therapy practice
2017
This empirical article presents four narratives from an ongoing qualitative PhD project about spirituality and family therapeutic practice. Using case studies and narrative vignettes, the article presents client perspectives on being able to discuss their spirituality in therapy, and the repercussions when therapists exclude it. The article refers to current research and provides some reflections on how we can understand spirituality in the context of family therapeutic practice; therapists for holistic, cultural, and ethical reasons should acknowledge the client’s spirituality. Therapists need to reflect on their own spirituality and how it may influence their relationships with clients. n…
Preparation and Characterization of Pulp and Paper Mill Sludge-Activated Biochars Using Alkaline Activation : A Box–Behnken Design Approach
2022
This study utilized pulp and paper mill sludge as a carbon source to produce activated biochar adsorbents. The response surface methodology (RSM) application for predicting and optimizing the activated biochar preparation conditions was investigated. Biochars were prepared based on a Box–Behnken design (BBD) approach with three independent factors (i.e., pyrolysis temperature, holding time, and KOH:biomass ratio), and the responses evaluated were specific surface area (SSA), micropore area (Smicro), and mesopore area (Smeso). According to the RSM and BBD analysis, a pyrolysis temperature of 800 °C for 3 h of holding and an impregnation ratio of 1:1 (biomass:KOH) are the optimum conditions f…
LU Studenšu korporāciju filistru biedrību sastāvi, 1937. gada 1. aprīlī
1937
Purification of recovered phosphoric acid by extracting aluminium with di-2-ethylhexyl phosphoric acid
2021
AbstractThe extraction of aluminium from dilute phosphoric acid with di-2-ethylhexyl phosphoric acid (DEHPA) was optimized using response surface methodology. The optimization was based on the experimental three-level central composite face-centred design (CCF) and was conducted on real-life samples. The three variables included were pH, extractant concentration and aqueous to organic phase ratio (AO). Under the optimized conditions (pH 2.5, 0.6 M DEHPA and AO ratio 1:2), extraction efficiency of 99% for aluminium in four extraction stages is achieved. The purified phosphoric acid solution can then be utilized by the fertilizing industry. Stripping tests for organic phase loaded with alumin…