Washing Treatment Research Articles

Study on the mechanism of ultrasonic enhanced removal of zinc and germanium from lead residue

Lead residue is the residue from the leaching process of zinc oxide dust containing germanium, which comprises a certain amount of valuable elements such as zinc and germanium. Conventional water washing treatment cannot effectively remove zinc and germanium from lead residue, resulting in a backlog of zinc and germanium in the system and raising production costs for enterprises. By using a dilute sulfuric acid solution and introducing ultrasonic waves for enhanced washing, the easily separated zinc and germanium are basically removed, while the residual zinc occurred as ZnS and germanium wrapped in lead sulfate are difficult to elute. The removal efficiency of zinc and germanium can reach 53.82% and 50.24%, respectively, which are 12.67% and 6.10% higher than conventional acid washing efficiency, and 31.10% and 22.51% higher than conventional water washing efficiency. During water washing, the hydrolysis of Zn2+ and Fe3+ results in low elution efficiency. While in pickling process, hydrolysis can be effectively inhibited. When use ultrasonic to enhance sulfuric acid washing, some ZnS dissolves, while the silica gel colloid that adsorbs germanium is destroyed, and germanium is released into the solution again, thus improving the removal efficiency of zinc and germanium. This article has reused more than half of the residual zinc and germanium in lead residue, and points out the direction for further reducing zinc and germanium residues in lead residue. It is of great significance for the comprehensive utilization of zinc and germanium resources.

Affected of Ameliorated Alkaline Water and Soil Amendments on Exchangeable Cation, Macro and Micronutrients in Sodic Soil under Drip Irrigation

The Field experiment was carried out at Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli using cotton (RCH- 20) as a test crop to examine the effect of ameliorated alkali water and soil amendments on soil properties, growth, and yield of hybrid cotton in sodic soil under drip irrigation. In this experiment, Drip irrigation with gypsum treatment water and drip irrigation with spent wash treatment water were used as main-plots treatments. Soil application of gypsum @ 50 % GR (5.2 t ha-1) and one time soil application of distillery spent wash @ 5 lakh litter ha-1 were imposed as sub-plot treatments. The treatment without amendments both under main plot and sub plots were used as control. The experiment was carried out using a strip-plot design with four replications. The application of additives through irrigation water (or) soil considerably decreased the pH of post-harvest soil. The soil exchangeable Ca and Mg were found significant due to soil application of amendments only and value ranged from 8.51 to 9.35 and 5.03 to 5.20 Cmol (p+) kg -1 respectively. The soil available nutrients N, P and K were found significant, and value range from 167 to 311, 15.4 to 21.5, 158 to 928 kg ha-1 respectively. The application distillery spent wash (DSW) and gypsum slightly increased the micronutrient cations range which from 4.80 to 6.85 mg kg-1 of Fe, 8.60 to 10.43 mg kg-1 of Mn, 0.64 to 0.88 of mg kg-1 of Zn, 1.10 to 1.42 mg kg-1 of Cu. The results of the field experiment revealed that application of amended alkali water and amended soil significantly increased all the growth and yield parameters of cotton. An increase in seed cotton yield of 701 and 544 kg ha-1 was recorded due to the application of gypsum treated water and DSW treated water respectively over control. Similarly, an increase of 773 and 973 kg ha-1 of seed cotton yield was recorded due to soil application of gypsum and DSW respectively over control. While considering the interaction effect, soil application of DSW along with gypsum bed treated water found to be the best for getting higher seed cotton yield (3015 kg ha-1) when compared to other treatment combination.

Carbonization of Corn Leaf Waste for Na-Ion Storage Application Using Water-Soluble Carboxymethyl Cellulose Binder.

Hard carbon materials are considered to be the most practical anode materials for sodium ion batteries because of the rich availability of their resources and potentially low cost. Here, the conversion of corn leaf biomass, a largely available agricultural waste, into carbonaceous materials for Na-ion storage application is reported. Thermal analysis investigation determines the presence of exothermic events occurring during the thermal treatment of the biomass. Accordingly, various temperatures of 400, 500, and 600 °C are selected to perform carbonization treatment trials, leading to the formation of various biocarbons. The materials obtained are characterized by a combination of methods, including X-ray diffraction, electron microscopy, surface evaluation, Raman spectroscopy, and electrochemical characterizations. The Na-ion storage performances of these materials are investigated using water-soluble carboxymethyl cellulose binder, highlighting the influence of the carbonization temperature on the electrochemical performance of biocarbons. Moreover, the influence of post-mechanochemical treatment on the Na-ion storage performance of biocarbons is studied through kinetic evaluations. It is confirmed that reducing the particle sizes and increasing the carbon purity of biocarbons and the formation of gel polymeric networks would improve the Na-ion storage capacity, as well as the pseudocapacitive contribution to the total current. At a high-current density of 500 mA g-1, a specific Na-ion storage capacity of 134 mAh g-1 is recorded on the biocarbon prepared at 600 °C, followed by ball-milling and washing treatment, exhibiting a reduced charge transfer resistance of 49 Ω and an improved Na-ion diffusion coefficient of 4.8 × 10-19 cm2 s-1. This article proposes a simple and effective technique for the preparation of low-cost biocarbons to be used as the anode of Na-ion batteries.

ACID WASH INFLUENCES ON PHYSICOCHEMICAL CHARACTERISTICS OF BAMBOO LEAVES ASH

Silica production from sandstone requires tremendous fossil resources that threaten our environment. Hence, greener resources from biomass should be utilized. One of them is from bamboo leaves which contain rich silica in ash. Even so, acid wash should be applied to achieve higher silica purity. This work aims to investigate the acid wash influences on the physicochemical characteristics of bamboo leaves ash (BLA). The treatment used 1 mol/L HCl under 1-h, 2-h, and no acid wash as a control. The BLA crystallography indicates a fully amorphous phase of silica. Interestingly, 1-h acid wash precisely reduces the silica purity from 95.35% to 94.74%, but it then increases to 96.06% under 2-h acid wash. It is also notified that the longer acid wash duration could alleviate leaves’ mechanical strength. After calcination, consequently, a smaller average particle size of BLA was nominated under 2-h acid wash (6.32 mm). It was then followed by 1-h acid wash (21.32 mm) and no acid wash (149.44 mm). The 2-h acid wash is concluded able to intensify silica purity as well as reduce the particle size of BLA. Finally, acid wash treatment becomes important to facilitate further BLA extraction in order to achieve high purity of silica.

Comparison of peroxyacetic acid and acidified sodium chlorite at reducing natural microbial contamination on chicken meat pieces

The spin-chill process at poultry processing plants involves the immersion of chicken carcasses in cold water (<5°C) often containing sodium hypochlorite which significantly contributes to the reduction of bacterial loads. Cutting carcasses into pieces, however, has been linked with increases in Campylobacter and Salmonella counts. Here, the efficacy of PAA and ASC on reducing bacteria on skin-on, bone-in thigh cuts was investigated. Three concentrations of ASC (60, 112, and 225 ppm) and PAA (50, 75, 100 ppm) were used. Thighs were dipped into sanitizer and tested for total viable bacterial counts, Campylobacter load, and prevalence of Salmonella. The efficacy of PAA and ASC was also compared with chlorine (8 ppm). All sanitizers exhibited a greater log reduction compared with water. PAA at both 75 and 100 ppm resulted in significantly higher log reductions compared with the water only. PAA at 100 ppm and 225 ppm ASC were the most effective at reducing Campylobacter. All wash treatments reduced the proportion of Salmonella positive samples, but the greatest reduction was observed for 225 ppm ASC. Both concentrations of ASC resulted in a greater reduction in total viable counts compared with chlorine.

Effect of Lignin or Lignosulfonate Addition on the Fire Resistance of Areca (Areca catechu) Particleboards Bonded with Ultra-Low-Emitting Urea-Formaldehyde Resin

As a way to accommodate the rising demand for “green” wood-based products, agricultural waste from Areca (Areca catechu) nut farms, which is generally burned on-site, can be used to raise the value of alternative lignocellulosic raw materials. This research aimed to investigate and evaluate the effect of technical lignin (kraft lignin or lignosulfonate) addition on particleboard properties from areca bonded with ultra-low-emitting urea formaldehyde (UF) resin. The physical properties, mechanical properties, and fire resistance of the laboratory-made particleboards were tested and evaluated in accordance with the applicable Japanese industrial standards (JIS). The highest density of 0.84 g/cm3 was determined for the laboratory boards, bonded with an adhesive mixture of UF resin and kraft lignin with three washing treatments. The lowest moisture content of 9.06%, thickness swelling of 71.16%, and water absorption of 129.17% were determined for the boards bonded with lignosulfonate with three washing treatments, with commercial lignin, and with lignosulfonate with five washing treatments, respectively. The highest MOR and MOE values, i.e., 113.49 kg/cm2 and 10,663 kg/cm2, respectively, were obtained for the particleboards bonded with lignosulfonate with five washing treatments. Interestingly, all laboratory boards exhibited good fire resistance following the UL-94 standard. Based on the gas torch test, the lowest weight loss of 16.7% was determined in the boards fabricated with lignosulfonate with five washing treatments. This study demonstrated that adding lignin-based fire retardants represents a viable approach to producing lignocellulosic composites with enhanced fire resistance and a lower carbon footprint.

Recycling of Polypropylene Recovered from a Composting Plant: Mechanical Behavior of Compounds with Virgin Plastic

The recycling of polypropylene recovered from waste discarded by a composting plant was investigated. The recovery involved a sorting step carried out by means of an optical infrared separator and a subsequent washing treatment. This method of processing allowed us to obtain polypropylene that was only slightly contaminated by other polymeric and inorganic materials. As many tens of tons of polypropylene could be recovered every year in this plant, recycling could be convenient from the economic point of view and beneficial for the protection of the environment. In fact, the landfill of this waste could be reduced in this manner. A possible mechanical recycling route was developed for the recovered plastic. The recycling was carried out by pelletizing the recovered polypropylene, mixing it with a commercial polypropylene feedstock, and manufacturing items by injection molding. In this way, tensile specimens containing different amounts of recycled polypropylene were processed and tested. Their tensile features were compared with those of a commercial polypropylene that was used as a reference. The elastic modulus and tensile strength were slightly worsened when using the recycled plastic, while the strain at failure significantly increased. Nonetheless, the tensile properties of compounds made by mixing recycled and virgin polypropylene were consistent with the characteristics that are expected for polypropylene-based plastics.

Simulated transmission and decontamination of Listeria monocytogenes biofilms from plastic cutting boards

The presence and persistence of Listeria monocytogenes biofilms on food contact surfaces are often considered as a critical source of cross-contamination of foodstuffs and hence pose a major risk in food safety. This is particularly an issue in numerous countries where knowledge of appropriate food hygiene practices is limited. In this study, the biofilm formation of L. monocytogenes (ATCC 19115) on plastic cutting boards as well as their transmission rates to selected food samples were simulated and evaluated. The effectiveness of the typical household washing practice in biofilm removal from artificially-contaminated plastic cutting boards was also assessed. Crystal violet indicated that L. monocytogenes biofilms on plastic cutting boards mature within 24 h, during which biofilm adhesion was the greatest with 1.62 OD value. The transfer rates of L. monocytogenes from artificially-contaminated plastic cutting board to cabbage (79.27%), chicken fillet (69.88%) and bread (83.25%) during the cutting process were determined. With regards to washing treatment, scrubbing with a commercial dishwashing liquid was shown to be effective at reducing microbial concentrations by 3–6 log CFU/cm2, with virtually all biofilms removed after 5 s of washing. Tap water rinsing on cutting boards was less effective with a mere decrease of 1–2 log CFU/cm2. The findings have provided an insight on the risks associated with the cross-contamination of L. monocytogenes and likely other pathogenic microbes which should be a concern everywhere in the world. Therefore, promoting a better awareness of proper cleaning practices, including the sanitization of cutting boards during food preparations is necessary.

Car wash wastewater treatment combination: A systematic review

Car wash wastewater is a source of water pollution. Processing car wash waste is crucial to prevent environmental pollution. In this issue, car wash treatment has the potential to sustain of clean water. However, the effective treatment of car wash wastewater is still being determined, complicated to solve, limited resource capabilities, inadequate surrounding environmental support, and very expensive processing costs. This systematic review paper aims to review the combination technology of car wash wastewater treatment systematically. A literature survey was conducted, and 11 research articles were found suitable for inclusion in the investigation, which extracted information, country of origin, and method used. The best 8 of 11 articles were removed as secondary data for writing this manuscript to be included in the analysis table. Studies on flocculation-column-flotation, coagulation-flocculation, ultra-microfiltration, coagulation-flocculation, electrocoagulation, sedimentation-filtration, filtration-ozonation, electrocoagulation-adsorption, and each n=1. This systematic review shows that ultrafiltration and microfiltration membrane treatment methods effectively remove pollutants from car wash wastewater.

Effect of Acidic Washing Treatment for Fe-N/C Catalyst Synthesized Using E-beam Irradiation

Effect of Acidic Washing Treatment for Fe-N/C Catalyst Synthesized Using E-beam Irradiation

OZONE MICRO-BUBBLE WATER (OMBW) AS RAW CHICKEN SANITIZER AGAINST Salmonella spp. AND THE EFFECT DURING TEMPERATURE ABUSE STORAGE

Ozone micro-bubble water (OMBW) can be used as sanitizer to wash fresh food products in order to eliminate microbiological contamination. A trial was carried out to determine the effectiveness of OMBW as a washing solution for raw chicken breast on the growth and concentration of cocktail mix Salmonella spp. (S. Enteritidis DMST 15676, S. Derby DMST 16879, S. Newport DMST 15675 and S. London DMST 7110). The washing treatment was carried out by dipping the artificially contaminated raw chicken breast in 1 and 2 ppm of OMBW or sterilized water (control) and shaken at 80 rpm for 5 minutes. The samples were kept at 4°C for 24 h before being exposed to the temperature abuse condition. The temperature abuse condition was carried out continuously from 10° C for 4, 6 and 8 h up to 30° C for 2 h. After the washing process, Salmonella spp. was greatly reduced by 1 and 2 ppm OMBW, significantly different (P&lt;0.05) from washing with sterilized water. Washing with 1 ppm OMBW, 2 ppm OMBW and sterilized water reduced the Salmonella spp. by 0.86, 0.72 and 0.41 log CFU/mL, respectively. Storage of raw chicken fillet at the recommended temperature of 4° C for 24 h, inhibited the growth of Salmonella spp. in samples that had previously been washed with 1 and 2 ppm OMBW, while samples washed with sterilized water showed a slight increase in Salmonella spp. numbers, but was not significantly different (P&gt;0.05) from the other treatments. At the end of temperature abuse storage, the Salmonella spp. concentration in all samples increased from the initial counts.

Investigating the use of Aspergillus niger fermentation broth as a washing treatment for arsenic and antimony co-contaminated soil.

High concentrations of arsenic and antimony contamination in soil are a potential risk to the ecological environment and human health. Soil washing can effectively and permanently reduce the soil contamination. This study used Aspergillus niger fermentation broth as a washing agent to remove As and Sb from contaminated soil. Characterization of organic acids in the fermentation broth by high-performance liquid chromatographic (HPLC) and chemically simulated leaching experiments revealed that oxalic acid played a significant role in removing As and Sb from the soil. The effect of washing conditions on the metal removal rate of Aspergillus niger fermentation broth was investigated by batch experiments, and the optimal conditions were determined: no dilution, pH 1, L/S ratio 15:1, and leaching at 25°C for 3h. The soils were washed three times under optimal conditions, with 73.78%, 80.84%, and 85.83% removal of arsenic and 65.11%, 76.39%, and 82.06% removal of antimony, respectively. The results of metal speciation distribution in the soil showed that the fermentation broth could effectively remove As and Sb on amorphous Fe/Al hydrous oxides in soil. The analysis of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) of soils before and after washing showed that the washing of Aspergillus niger fermentation broth had a minor effect on the structural changes of soils. After washing, soil organic matter and soil enzyme activity were increased. Thus, Aspergillus niger fermentation broth shows excellent potential as a washing agent for removing As and Sb from soils.

Multifunctional PVDF nanofiber materials for high efficiency dual separation of emulsions and unidirectional water penetration

Multifunctional fibrous materials are desirable for smart garments, dual separation of oil-in-water (O/W) and water-in-oil (W/O) emulsions, and membrane filtration, however, the contradictory permselectivity and sophisticated preparation method impede the large-scale manufacture and their wide applications. Herein, the multifunctional polyvinylidene fluoride (PVDF) nanofibrous materials were fabricated by the facile washing treatment of electrospun PVDF-polyvinylpyrrolidone nanofiber membrane (WPVDF). The WPVDF nanofiber membranes with hierarchical and porous structure illustrated interesting wettability, such as superamphiphilic in air, underoil superhydrophobic, and underwater superoleophobic. Consequently, the WPVDF membranes achieved intriguing dual separation performance towards both O/W and W/O emulsions, involving separation efficiency >98.5% and permeation flux >12940.1 L m-2h−1 towards O/W emulsions, separation efficiency >99.5% and permeation flux >8264.3 L m-2h−1 towards W/O emulsions, and good reusability within 20 cycles. Furthermore, the WPVDF/PVDF composite membranes exhibited intriguing unidirectional water penetration performance and long-term stability, the water can only penetrate from hydrophobic PVDF layer to hydrophilic WPVDF layer and cannot occur in reverse direction. The fabrication of such multifunctional PVDF nanofibrous materials could be potentially applied in the field of smart garments, water treatment, and flow control devices.

A reusable electrochemiluminescence biosensor controlled by a nanochannel gating system for T-2 toxin detection

A reusable electrochemiluminescence (ECL) biosensor based on the switchable gating property of nanochannels has been successfully developed and applied in the detection of T-2 toxin. The sensing interface was achieved by modifying nanoporous anodic aluminum oxide membrane with gold nanoparticles and T-2 aptamers, which has a switchable gating property triggered by the target. Once triggered by the target, the gating system could be switched from the "OFF" state to the "ON" state allowing diffusion of ascorbic acid (AA) and H2O2. Due to the consumption of reactive oxygen species by AA, ECL signals of luminol/Au NPs was significantly inhibited. Through the treatment of heating and washing, captured T-2 toxin can be fully released and the gating system can be switched to the “OFF” state and applied in the following detection. Due to the spatial separation, reactivation of the sensing interface by repeated heating and washing will not affect the ECL emitters after repeated tests. This biosensor was applied in the analysis of actual samples. There’s a good linear relationship between ECL intensity and the logarithm value of the concentration in the range of 10 pg mL−1 to 100 μg mL−1 with a limit of detection of 3.2 pg mL−1.

Characterization of the Bacterial Communities in Cichorium intybus According to Cultivation and Storage Conditions.

Chicory leaves (Cichorium intybus) are widely consumed due to their health benefits. They are mainly consumed raw or without adequate washing, which has led to an increase in food-borne illness. This study investigated the taxonomic composition and diversity of chicory leaves collected at different sampling times and sites. The potential pathogenic genera (Sphingomonas, Pseudomonas, Pantoea, Staphylococcus, Escherichia, and Bacillus) were identified on the chicory leaves. We also evaluated the effects of various storage conditions (enterohemorrhagic E. coli contamination, washing treatment, and temperature) on the chicory leaves' microbiota. These results provide an understanding of the microbiota in chicory and could be used to prevent food-borne illnesses.

Ionothermal synthesis of activated carbon from waste pet bottles for dye waste water treatment

The production and use of poly-ethylene terephthalate (PET) bottles in packaging have increased significantly. Thus, PET bottles have become a significant plastic waste with environmental problems. Currently, the conventional methods for producing activated carbons (ACs) from waste PET are unsustainable, complex, and unfeasible. As a result, ionothermal synthesis (IS) of waste PET bottles impregnated with choline chloride-urea (CU) deep eutectic solvent (DES) was carried out in order to prepare ACs. The obtained ACs were characterized using XRD, CHNS Elemental analysis and FTIR. The as-prepared ACs were effective as adsorbents for dye adsorption from dye waste water. Specifically, the AC obtained from pristine waste PET bottles (956 mgg−1 at 100 ppm) displayed higher adsorptive capacity compared to the ACs obtained from CU-DES impregnated PET flakes (550mgg−1 at 100ppm). Even though it was expected that the use of CU-DES required no post-synthesis washing or higher temperature treatments might be required to improve the adsorptive capacity of the ACs obtained from IS.This research work established that the synthesis of AC from abundant waste PET bottles using a sustainable and facile method could facilitate its commercial application. Also, this work represents the first attempt to produce activated carbons from PET using low temperature annealing in the presence of limited air, instead of the usual pyrolysis.

Effect of trans-cinnamaldehyde nanoemulsion wash on chicken embryo development in fertilized eggs

Cleanliness of eggs is critical in successful hatching egg operations. The objective of this study was to investigate the effect of trans-cinnamaldehyde nanoemulsion (TCNE) wash treatments, as a sanitation strategy, on embryonic development in fertilized eggs. Trans-cinnamaldehyde is a generally recognized as safe status phytochemical obtained from cinnamon bark. TCNE were prepared with emulsifiers Tween 80 (Tw.80) or gum Arabic and lecithin (GAL) by sonication. Day-old fertilized eggs were subjected to TCNE wash treatments at 34°C for 5 min, followed by 18 d of incubation at 37.7°C. Washing of fertilized eggs with TCNE-Tw.80 or GAL at 0.48% concentration did not significantly alter the egg weight at d 18 of incubation, as compared to baseline and control (P > 0.05). The egg weight loss (calculated as percentage) did not differ significantly between eggs subjected to nanoemulsion wash treatments and control eggs (P > 0.05). In case of embryo fertility and mortality, for baseline and control, ∼ 95% fertility rate was achieved, with combined early and midterm mortality at 16%. Likewise, TCNE-Tw.80 or TCNE-GAL resulted in 95% fertility (P > 0.05), with 11% and 17% combined early and midterm mortality, respectively. Furthermore, TCNE wash treatments did not differ significantly in yolk sac and embryo weight (as compared to control) and did not affect the length of the d 18 embryo (P > 0.05). Moreover, TCNE wash treatments did not alter tibia weight and length (P > 0.05). Results suggest that TCNE could potentially be used as a natural antimicrobial for fertilized egg sanitation. Further studies in industry settings are warranted.

Fine-Tuned Synthesis for Reducing Residual Lithium in Ni-Rich Cathode Materials for Lithium-Ion Batteries

Incidentally generated residual lithium on the surface during the synthesis of Ni-rich cathode materials for lithium-ion batteries has been considered one of the most serious problems to be solved. In this work, a suitable condition for simple washing and post-heat treatment with additional lithium salt process for preparing LiNi0.8Co0.1Mn0.1O2 is optimized through a systematic evaluation. By varying amount of additional lithium salt, the most appropriate input is found to be 5 wt % in terms of electrochemical performance, such as initial capacity, capacity retention, and rate capability. In addition, it is verified by several techniques that it has the ideal composition (lithium/transition metal = 1:1) and the stable structure of R3̅m. From electrochemical impedance spectroscopy, it is found that the good performance of the cell assembled using the optimized material is originated from lowering resistance between the cathode and the electrolyte.

The Fate of Heavy Metals and Risk Assessment of Heavy Metal in Pyrolysis Coupling with Acid Washing Treatment for Sewage Sludge.

Pyrolysis is an emerging and effective means for sludge disposal. Biochar derived from sludge has broad application prospects, however, is limited by heavy metals. In this study, the fate of heavy metals (HMs) in pyrolysis coupling with acid washing treatment for sewage sludge was comprehensively investigated for the first time. Most of the HMs redistributed in the pyrolyzed residues (biochar) after pyrolysis, and the enrichment order of the HMs was: Zn > Cu > Ni > Cr. Compared with various washing agents, phosphoric acid presented a superior washing effect on most heavy metals (Cu, Zn, and Cr) in biochars derived at low pyrolysis temperature and Ni in biochars derived at high pyrolysis temperature. The optimal washing conditions for heavy metals (including Cu, Zn, Cr, and Ni) removal by H3PO4 were obtained by batch washing experiments and the response surface methodology (RSM). The total maximum HM removal efficiency was 95.05% under the optimal washing specifications by H3PO4 (acid concentration of 2.47 mol/L, L/S of 9.85 mL/g, and a washing temperature of 71.18 °C). Kinetic results indicated that the washing process of heavy metals in sludge and biochars was controlled by a mixture of diffusion and surface chemical reactions. After phosphoric acid washing, the leaching concentrations of HMs in the solid residue were further reduced compared with that of biochar, which were below the USEPA limit value (5 mg/L). The solid residue after pyrolysis coupling with acid washing resulted in a low environmental risk for resource utilization (the values of the potential ecological risk index were lower than 20). This work provides an environmentally friendly alternative of pyrolysis coupling with acid washing treatment for sewage sludge from the viewpoint of the utilization of solid waste.

Understanding factors responsible for the slow decline of soil-transmitted helminthiasis following seven rounds of annual mass drug administration (2012–2018) among school children in endemic counties of Kenya: A mixed method study

Soil-transmitted helminthiasis (STH) continue to be a significant health problem in Sub-Saharan Africa especially among school children. In Kenya, treatment of over five million children has been conducted annually in 28 endemic counties since the year 2012. However, the latest monitoring and evaluation (M&E) results indicated a slow decline of prevalence and intensity of STH in some counties after the seven rounds of annual mass drug administration (MDA). The current study sought to determine the factors associated with the slow decline in prevalence and intensity of STH among school children participating in the school deworming programme. Mixed methods cross-sectional study was conducted in three endemic counties of Kenya. For quantitative technique, simple random sampling was used to select 1,874 school children from six purposively selected primary schools. The school children were interviewed, and a single stool collected and analysed using Kato-Katz technique. While for qualitative methods, 15 focus group discussions (FGDs) were conducted with purposively selected parents/guardians of school children. Data was collected through voice records using FGD and analyzed using NVIVO. Prevalence of any STH infection was 30.8% (95%CI: 28.7-32.9), with the highest prevalence observed in Vihiga County (40.7%; 95%CI: 37.4-44.4). Multivariable analysis revealed that geographical location (OR = 3.78, (95%CI: 1.81-7.88) p<0.001), and not washing hands after defecation (OR = 1.91, (95%CI: 1.13-3.20) p = 0.015) were significantly associated with any STH infection. For qualitative analysis, majority of the parents/guardians of SAC felt that poor water sanitation and hygiene practices (WASH) both in school and household level could be a cause of continued STH infection. Also failing to include the rest of the community members in the MDAs were mentioned as possible contributors to observed slow decline of STH. There was moderate STH prevalence and mean intensity despite the seven rounds of repeated annual MDA. The study recommends a revamped awareness creation on WASH and community wide treatment.