Ahmed Hussen

• Professor (Associate) at Addis Ababa University

This study presents an innovative approach to enhancing the efficiency of composting organic municipal solid waste (MSW) and improving fertilizer quality using a pilot Aerated Static Pile (ASP) system with extremophilic lake sediment as a microbial inoculum. By optimizing waste mixing ratios, refining operational parameters, and assessing the quali...

Detecting and quantifying pharmaceutical compounds in various environmental matrices is complex and challenging. This difficulty stems from the trace levels at which these compounds are found and the lack of analytical methods that are rapid, cost-effective, and portable. To address these challenges, this study aimed to develop microfluidic paper-b...

In the highland areas of Ethiopia, farming communities are struggling with severe soil erosion, which is putting significant strain on ecosystems and food production capabilities. Many smallholder farmers in the basin cultivate fragile soils on steep slopes, often without proper management practices, leading to substantial soil loss, ecosystem degr...

Purpose This study aims to optimize the process of converting organic municipal solid waste (MSW) into organic fertilizer using a pilot Aerated Static Pile (ASP) composting system. It focuses on identifying the best waste mixing ratios, optimizing operational parameters, and evaluating the quality of the resulting fertilizer to enhance waste manage...

In this study a paper-based analytical device was developed using screen printing technique for the determination of particulate iron from welding fumes. The operational parameters such as volume and concentration of 1,10-phenanthroline, volume and concentration of hydroxylamine were optimized by the Box Behnken Design (BBD) using Minitab. Addition...

In the present study, a sensitive microfluidic paper-based analytical device (μ-PADs) integrated with adsorption enrichment procedure was developed to analyze Cr(VI) in water samples. The affecting factors, including pH and amounts of reagents were optimized. The limit of detection of 0.0015 mg L−1 and linear range of 0.005–2 mg L−1 were achieved w...

Microalgae have the ability to utilize nutrients present in wastewater and generate biomass that is abundant in carbohydrates, lipids, and proteins. The ability of microalgae to integrate wastewater management and biofuel production makes them a promising solution for enhancing environmental sustainability. The objective of this study was to assess...

This study aimed to determine the quantity and quality of source separated organic household solid waste (SSOHSW) generation in Addis Ababa, Ethiopia with particular reference to its bioenergy recovery potential using bioconversion technologies. A multi-stage probability sampling approach was employed to collect data from 304 households representin...

Increasing waste production and its disposal into the environment without treatment and resource recovery is considered as a threat to the environment and human health. This study aimed to determine the current commercial and institutional solid waste generation rates, physicochemical and compositional analyses at selected sub-cities in Addis Ababa...

Carbohydrates are more likely to be found in lipid-extracted microalgal biomass, which can be used to produce bioethanol with different pretreatment methods. The objective of this study was to prepare lipid-extracted biomass of Scenedesmus sp. grown in anaerobically digested brewery effluent for bioethanol production. Pretreatments such as autoclav...

A simple, fast, low-cost and sensitive microfluidic paper-based analytical device (u-PADs) integrated with the co-precipitation enrichment procedure was developed to analyse Ni(II) in tap and mineral water samples. The impacting factors, including pH, centrifugation (5 min at 4000 rpm), and amounts of reagents were optimized. The limit of detection...

The concentration levels of some selected common (Mg, K, Ca), heavy (Cr, Mn, Co, Ni, Cu, Zn) and toxic metals (Cd and Pb) were determined in coffee (Coffea arabica) beans, leaves and supportive soil of Gedeo zone, Ethiopia using Flame Atomic Absorption Spectrometer after microwave digestion of the samples. In coffee beans, among the common metals,...

Microfluidic paper-based analytical devices (μ-PADs) are a new technology platform for the development of extremely low-cost sensing applications. In this study, μ-PADs has been developed for quantitative determination of carbamate pesticides. Key experimental parameters including concentration and volume of acetylcholinesterase, acetylthiocholine...

Several physicochemical techniques have been widely studied for heavy metals removal despite most of them are associated with challenges of higher cost, accessibility, and complex technical feasibility. In this study, nano-sorbent materials were developed from a naturally available clay matrices and its heavy metals (Cu2+ and Pb2+) removal capacity...

A microfluidic paper-based analytical device (µPAD) is a new technology platform for extremely low-cost sensing applications. This study aimed to explore for an inexpensive alternative fabrication method. Accordingly, a simple wax screen printing fabrication manageable with locally available materials has been elaborated and successfully demonstrat...

There has been an increasing challenge from the emission of methylene blue (MB) dye-containing wastewater and its management methods in industry. The sorption process is one conventionally used method. In this study, nanoclay, nano zero valent iron (nZVI), and iron impregnated nanoclay were prepared and studied for the removal of MB dye in batch mo...

The present study focused on improving sensitivity to trace levels of Cu(II) by subjecting microfluidic paper-based analytical devices (μ-PADs) to a preconcentration process via coprecipitation using aluminum hydroxide. The experimental conditions were optimized for the pH of the coprecipitation, centrifugation, and amounts of reagents that were de...

The aim of this study was to select a suitable pretreatment method and optimize total reducing sugar extraction from indigenous Scenedesmus sp. grown on brewery wastewater for bioethanol production. Microalgal biomass was pretreated using a microwave, autoclave, water bath, and oven with HCl, H2SO4, NaOH, and KOH, followed by the optimization of th...

Correction for ‘Nano zero valent iron (nZVI) particles for the removal of heavy metals (Cd ²⁺ , Cu ²⁺ and Pb ²⁺ ) from aqueous solutions’ by Mekonnen Maschal Tarekegn et al. , RSC Adv. , 2021, 11 , 18539–18551. DOI: 10.1039/D1RA01427G.

For the past 15 years, nanoscale metallic iron (nZVI) has been investigated as a new tool for the treatment of heavy metal contaminated water. The removal mechanisms depend on the type of heavy metals and their thermodynamic properties. A metal whose redox potential is more negative or close to the reduction potential of Fe(0) is removed by the red...

The use of wastewater as a nutrient source for microalgae cultivation is considered as a cost-effective approach for algal biomass and biofuel production. The microalgal biomass contains carbohydrates that can be processed into bioethanol through different extraction methods. The objective of this study is to optimize the microwave-assisted extract...

Speciation of chromium (Cr) was demonstrated using microfluidic paper-based analytical devices (μ-PADs) that permit the colorimetric determination of hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) via online oxidation. The μ-PADs consist of left and right channels that allow the simultaneous measurements of Cr(VI) and total Cr based...

The municipal and agricultural wastes are promising source of ligniocellulosic biomasses (LBs) for bioethanol production. However, the pretreatment-hydrolysis (P–H) of LB is the most difficult process in bioethanol production due to high crystallinity of LB compositional structures. In this study, p-toluenesulphonic acid (PTSA) was investigated for...

Background The combination of nutrient removal using microalgae from wastewater with carbohydrate production has been considered as a promising approach for sustainable wastewater treatment and production of valuable products such as biofuels. In Ethiopia, urbanization and industrial development are not in tandem with wastewater treatment system Th...

Biodiesel was prepared by extracting oil from Cladophora glomerata green algae followed by transesterification of the oil using NaOH as a catalyst. The algae Oil extraction was carried out using two different techniques (Soxhlet and refluxing) and similar oil yield was obtained (23-24%). The resulting biodiesel showed desirable physical and chemica...

Microfluidic paper-based analytical devices (μ-PADs) fabricated in Japan were employed for the determination of total chromium (Cr) in water, soil, and lettuce irrigated with wastewater in Ethiopia. The μ-PADs, which were printed by wax printing in Japan, were transported to Ethiopia and prepared for the determination of total Cr by adding appropri...

Fresh cow's milk samples were collected from four dairy farms of Arero, Gololcha, Odomike, and Semero sites of Borena Zone, Ethiopia and preserved in a deep freezer (-20℃). The milk samples were digested by the optimized microwave digestion method using HNO 3 and H 2 O 2. The concentrations of Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb were determined by Fl...

The powder of root bark of Malva parviflora (Malvaceae) was successively extracted with petroleum ether (b.p. 60–80 °C), chloroform and ethanol. The chloroform extract showed antibacterial activity against Staphylococcus aureus and Escherichia coli, whereas the ethanolic extract showed antibacterial activity against only S. aureus. The chloroform e...

Removal of hexavalent chromium ions [Cr(VI)] from aqueous solutions by adsorbents prepared from barks of Acacia albida of Fabaceae family and leaves of Euclea schimperi of Ebenaceae family has been studied by batch adsorption technique. Double-beam UV–visible spectrophotometer was used to monitor the concentration of Cr(VI). The influence of contac...

In this study, the levels of DDT and its metabolite residues were determined in chewable parts of Catha edulis plants grown in the southern part of Ethiopia. The levels of p,p'-DDT and p,p'-DDE were found to be in the range of 10.8-19.7 and 3.5-18.6 μg/kg, respectively. These data revealed that the residue being detected is from recent applications...

This research attempts to assess pesticide use, practice and risk in Gedeo and Borena Zones. Three sample districts have been selected purposively from these zones and four sub districts from each district. Primary data was collected through in depth interview and group discussion. Results show that people in the sample area use pesticides for crop...

The defluoridation of ground water is regarded as one of the key areas of attention among the universal water community. The present investigation deals with fluoride removal from aqueous solution by thermally activated biosorbents prepared from banana (Musa paradisiaca) peel and coffee (Coffea arabica) husk. Fluoride ion selective electrode was us...

Fish is one of our most valuable sources of protein food. Worldwide, people obtain about 25% of their animal protein from fish and shellfish. Fish, apart of being a good source of digestible protein vitamins, minerals and polyunsaturated fatty acids (PUFA), are also an important source of heavy metals. Some of the metals found in the fish might be...

Sugarcane bagasse and wheat straw were applied for the removal of nitrite ions from water samples. Batch experiments were conducted to establish optimum pH (5), initial nitrite concentration (5 mg/L), adsorbent dose (3 mg/L) and contact time (90 min). Under the optimized conditions, raw sugarcane bagasse was found to be a more effective (removal ef...

The in vitro toxicity of Millettia ferruginea darasana (family: Fabaceae) was tested against the larvae adult male and female of a three-host tick, Amblyomma variegatum Fabricius (family: Ixodidae or hard tick), known as ‘tropical bont tick’ parasitic mainly to cattle found in Ethiopia and other equatorial Africa. The 20, 40, 60, 80 and 100 % conce...

Upper Awash Agro Industry Enterprises (UAAIE) is one of the major state farms in Ethiopia with known large-scale pesticide use. Although organochlorine pesticides (OCPs) have been applied for about three decades, no studies have been carried out on levels of residue in the region. In this work a fast selective pressurised liquid extraction (SPLE) m...

A selective pressurized liquid extraction (SPLE) procedure capable of performing simultaneous extraction and clean-up has been demonstrated for multi-residue analysis of organochlorine pesticides (OCPs) in soil. The final method was performed at 100 degrees C for 3 x 10 min using acetone/n-heptane (1:1, v/v). Florisil was placed inside the extracti...

The effectiveness of extracting p,p'-DDT and p,p'-DDE from aged contaminated soil samples by means of pressurized liquid extraction (PLE) was evaluated. Two soil samples, which were contaminated more than 10 years ago, were used in the investigation. The static extraction time was optimised and then validated against the total sum of target analyte...

The Extracting Syringe (ESy), a novel membrane-based sample preparation technique directly coupled as an autosampler to gas chromatography, has been employed for the analysis of organochlorine pesticides (OCPs) in raw leachate water. The ESy has also been applied for extraction of OCPs from contaminated soil samples and its performance has been com...

Pressurized liquid extraction (PLE) was investigated for the extraction of two endosulfan isomers and their metabolite from two real contaminated soil samples. PLE for 3x10min at 100 degrees C was proven to be more exhaustive than Soxhlet extraction (SOX) in one soil sample. On the other soil sample investigated the method was found to be equally e...