Coagulation in combination with anaerobic digestion for enhancement of resource recovery from faecal sludge.

Poorly managed faecal sludge (FS) poses significant challenges to public health and the environment. Anaerobic digestion (AD) of FS provides an effective method for energy recovery while reducing FS associated threats. Recognizing the critical role of the dewatering process before AD, this study investigates the synergistic application of chemical coagulation and mesophilic AD for synthetic FS treatment. FeCl3, AlCl3, Fe2(SO4)3, poly ferric sulfate (PFS) and poly aluminium ferric chloride (PAFC) were utilized at varying dosages to examine their impact on FS properties and subsequent biogas production from the dewatered FS. It was found that coagulation enhances sedimentation efficiencies and dewaterability through mechanisms such as charge neutralization, charge patching and bridging, thereby improving the FS feasibility for AD. Notably, polymer coagulant PFS showed good performance in balancing pollutant removal and methane recovery, contributing to facilitating the hydrolysis and acidogenesis microorganisms involved in the AD process. Optimal dosage was identified at 150 mg/g TS (1.7 g/L FS), achieving prominent removal efficiencies for total COD (67%), turbidity (85%), and total phosphorus (60%), while simultaneously enhancing AD performance with specific CH4 production reaching 517 ml CH4/g VS or 24.8 ml CH4/g AD wet feedstock compared to 309 ml CH4/g VS or 2.7 ml CH4/g AD wet feedstock in untreated FS.

Removal of organic micropollutants from water by adsorption on thermo-plasma expanded graphite encapsulated into calcium alginate.

Nowadays, public concern is focused on the degradation of water quality. For this reason, the development of innovative technologies for water treatment in view of (micro)pollutant removal is important. Indeed, organic (micro)pollutants, such as pharmaceuticals, herbicides, pesticides and plasticizers at concentration levels of µg L-1 or even ng L-1 are hardly removed during conventional wastewater treatment. In view of this, thermo-plasma expanded graphite, a light-weight innovative material in the form of a powder, was encapsulated into calcium alginate to obtain a granular form useful as filtration and adsorption material for removal of different pollutants. The produced material was used to remove atrazine, bisphenol-A, 17-α-ethinylestradiol and carbamazepine (at concentration levels of 125, 250 and 500 µg L-1) by top-down filtration. The effect of flow rate, bed depth and adsorbent composition was evaluated based on breakthrough curves. The experimental data was analysed with the Adams-Bohart model in view of scale-up. Under optimal conditions, removal and adsorption capacity of respectively about 21%, 21%, 38%,42%, 43 µg g-1, 44 µg g-1, 37 µg g-1 and 87 µg g-1 were obtained for atrazine, bisphenol, 17-α ethinylestradiol and carbamazepine when using 0.12 g of thermo-plasma expanded graphite to treat 200 mL at 500 µg L-1 (for each compound) of solution obtaining at contact time of 20 min. The granular form of TPEG obtained (GTPEG) by entrapping in calcium alginate results to have a good adsorbent property for the removal of carbamazepine, atrazine, bisphenol A and 17-α ethinylestradiol from water at concentration levels between 250 and 500 µg L-1. Promising results confirm the adsorbent properties of TPEG and push-up us to investigate on its application and improve of its performance by evaluating different entrapping materials. Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-023-00876-9.

Removal of several pesticides in a falling water film DBD reactor with activated carbon textile: Energy efficiency.

Bio-recalcitrant micropollutants are often insufficiently removed by modern wastewater treatment plants to meet the future demands worldwide. Therefore, several advanced oxidation techniques, including cold plasma technology, are being investigated as effective complementary water treatment methods. In order to permit industrial implementation, energy demand of these techniques needs to be minimized. To this end, we have developed an electrical discharge reactor where water treatment by dielectric barrier discharge (DBD) is combined with adsorption on activated carbon textile and additional ozonation. The reactor consists of a DBD plasma chamber, including the adsorptive textile, and an ozonation chamber, where the DBD generated plasma gas is bubbled. In the present paper, this reactor is further characterized and optimized in terms of its energy efficiency for removal of the five pesticides α-HCH, pentachlorobenzene, alachlor, diuron and isoproturon, with initial concentrations ranging between 22 and 430 µg/L. Energy efficiency of the reactor is found to increase significantly when initial micropollutant concentration is decreased, when duty cycle is decreased and when oxygen is used as feed gas as compared to air and argon. Overall reactor performance is improved as well by making it work in single-pass operation, where water is flowing through the system only once. The results are explained with insights found in literature and practical implications are discussed. For the used operational conditions and settings, α-HCH is the most persistent pesticide in the reactor, with a minimal achieved electrical energy per order of 8 kWh/m3, while a most efficient removal of 3 kWh/m3 or lower was reached for the four other pesticides.