The chemistry at the heart of the study is fermentation, the same family of microbial processes that turns sugars into alcohol or yogurt into existence. In dark fermentation, hydrogen-producing bacteria break down complex organic matter into hydrogen, organic acids, and alcohols without needing light or oxygen. Photo fermentation, the second stage, uses photosynthetic bacteria that capture light energy to generate ATP, which they then spend to ferment the organic acids left behind by the first stage into more hydrogen. Each stage alone is inefficient, converting only a fraction of the feedstock into gas, but the two-stage combination recovers substantially more hydrogen because the fatty acids that would otherwise accumulate as waste in dark fermentation become the fuel for the second act. This sequential logic formed the backbone of the experimental design.

The team collected fresh leachate from the Al Multaqa landfill in Al Amerat, Oman’s first engineered landfill, which receives roughly 200 cubic meters of leachate per day, along with household food waste and sewage sludge from a local treatment plant to serve as the microbial inoculum. Characterization of the leachate revealed a chemical oxygen demand of about 43,000 milligrams per liter and a biochemical oxygen demand of roughly 27,000 milligrams per liter, values indicating a highly biodegradable, organic-rich liquid drawn from a young landfill cell. Iron and magnesium concentrations fell within ranges previously reported as favorable for hydrogen-producing microbes. The food waste was composed of about 50 percent fruit and vegetables, 25 percent protein, and 20 percent carbohydrate, a composition typical of Omani kitchen discards, which collectively represent more than 50 million Omani rials in wasted value each year.

Eight experimental schemes probed the variables that matter most. Four tested different ratios of landfill leachate to food waste, from pure leachate to pure food waste, under dark fermentation at 30 degrees Celsius and a pH of 5.5. The sweet spot turned out to be a 75:25 leachate-to-food-waste blend, which yielded 2.507 milliliters of hydrogen per liter of medium at a rate of 0.021 milliliters per liter per hour, roughly double the output of either feedstock alone. The explanation lies in the carbon-to-nitrogen ratio: leachate brings abundant nitrogen that supports microbial growth, while a modest dose of carbon-rich food waste supplies the electrons that ultimately end up in hydrogen gas. Acetic and propionic acids dominated the fatty acid profile of the best-performing scheme, confirming that the microbial community was operating along productive metabolic pathways rather than being stalled by acid accumulation.

Pretreatment emerged as a make-or-break variable. When the researchers skipped the heat treatment of the inoculum and feedstock, hydrogen production fell to zero even though fatty acid concentrations soared, a signature of acid accumulation poisoning the hydrogen-producing metabolism. Similarly, omitting the centrifugation and sterilization of the dark fermentation effluent before feeding it to the photo fermentation stage cut hydrogen output and left a heavy load of unconverted acids. In the single-stage experiments using only food waste, smaller medium volumes outperformed larger ones: a scheme with 40 percent more substrate and inoculum produced 28.74 percent less hydrogen per liter, echoing earlier reports that smaller reactors avoid substrate inhibition. Hydrogen purity in the collected gas ranged from under 5 percent to over 60 percent depending on the blend and treatment regime.

With technical feasibility established at bench scale, the team scaled the concept to a hypothetical plant processing 50 cubic meters of leachate per day alongside collected food waste, using literature benchmarks of 200 to 400 milliliters of hydrogen per liter for dark fermentation and 700 to 1000 milliliters per liter for photo fermentation. Four plant configurations were modeled: two-stage fermentation with full pretreatment, two-stage with treatment only before the photo stage, two-stage with treatment only before the dark stage, and single-stage dark fermentation of food waste alone. Plant capacities ranged from 2.7 to 12.13 kilograms of hydrogen per day, and capital costs clustered around 25.5 to 25.8 million US dollars, dominated by bioreactors and gas compression equipment.

The economics told a striking story. All four scenarios produced a positive net present value over a ten-year lifetime at a 5 percent discount rate, but Scenario 2, the two-stage system with treatment applied only before photo fermentation, came out on top with an NPV of 45.06 million US dollars and cumulative revenue of roughly 80.65 million dollars. Revenue flows from four streams: hydrogen sold at approximately 12 dollars per kilogram, carbon dioxide captured during gas separation, biofuel derived from volatile fatty acids, and compost recovered from the microfiltration stage. Operating costs were driven primarily by energy and maintenance, with heating vessels alone consuming 45.6 percent of total energy demand. Notably, the feedstocks themselves cost nothing; in fact, facilities can collect tipping fees for accepting waste, a structural advantage over electrolysis plants that must purchase purified water and electricity.

Sensitivity analysis showed the discount rate and hydrogen price exert the strongest influence on profitability, while carbon pricing barely moves the needle. A 30 percent increase in the discount rate dropped Scenario 2’s NPV to 41.63 million dollars, while a 30 percent decrease lifted it to 48.90 million. The Oman results sit within a global spectrum of biohydrogen economics, from a modest 4.7 million dollar NPV for rice straw fermentation in Malaysia to industrial-scale biomass systems in Bangladesh and Nigeria exceeding 480 million dollars, suggesting that revenue diversification through biorefinery integration is what separates marginal projects from compelling ones.

The authors are candid about limitations. The experiments were designed as a proof of concept without replicates, and the economic model relied on literature-based hydrogen prices rather than localized Omani market data. Pilot-scale validation will be essential before commercial deployment, since hydrogen productivity at industrial scale often diverges from laboratory performance. Still, the broader implications are hard to ignore: waste streams that cost municipalities money to manage can be converted into a zero-emission energy carrier, compost, and biofuel, aligning circular-economy practice with national climate goals. As global hydrogen strategies mature, the study argues that waste-derived biohydrogen deserves formal recognition within green hydrogen frameworks, supported by feedstock-based subsidies, carbon credit mechanisms, and standardized purity certification. If Oman’s landfills can become hydrogen factories, the model could travel well beyond the Gulf.

Subject of Research: Techno-economic feasibility of biohydrogen production from landfill leachate and food waste via dark and photo fermentation in Oman

Article Title: Economic feasibility and optimization of biohydrogen gas production- a case study in Oman

Article References: Barghash, H., Farai, S. A., AlRashdi, Z., & Okedu, K. E. (2026). Economic feasibility and optimization of biohydrogen gas production- a case study in Oman. Results in Engineering, 32, Article 113232. https://doi.org/10.1016/j.rineng.2026.113232

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113232

Keywords: biohydrogen, landfill leachate, food waste, dark fermentation, photo fermentation, techno-economic analysis, Oman Vision 2040, circular economy, waste-to-energy, net present value, renewable energy, Al Multaqa landfill

The research team, led by Syed Ariful Haque of Sultan Qaboos University together with Saud M. Al Jufaili, Mohammad Chhiddikur Rahman, and Mohammad Shafiur Rahman, surveyed 120 licensed fishers randomly selected from a population of 3,888 across the three Muscat landing sites. Data were collected between August 2024 and March 2025 using a mixed-methods design that combined face-to-face structured interviews with three established assessment tools developed by the FAO and the University of Greenwich: the Informal Fish Loss Assessment Method for qualitative scoping, the Load Tracking Method for direct observational measurement, and the Questionnaire Loss Assessment Method for structured self-reporting. Enumerators physically followed consignments from landing site to auction hall, weighing rejected fish before disposal and cross-verifying official catch weights with calibrated scales. Organoleptic testing distinguished good-quality from lower-quality fish, and price differentials observed during live auctions allowed the team to convert quality degradation directly into monetary terms.

The headline numbers are striking. The average fisher reported total post-harvest losses of 125.5 Omani Rials per fishing day, roughly 326 US dollars at Oman’s fixed exchange rate, with individual losses ranging from 6 to 259 OMR per day. Because each sampled vessel is associated with a single licensed fisher, these figures represent the gross market value of downgraded or rejected catches attributable to that fisher, not net income losses after operating costs. Even so, the daily loss figures sit uncomfortably close to the monthly income brackets reported by respondents, most of whom earned between 301 and 400 OMR per month from fishing alone. With 60.8 percent of fishers working part-time and household sizes averaging six members, the scale of value leakage at the very first node of the supply chain carries obvious implications for coastal livelihoods and food security.

Losses were not distributed evenly across species. The team ranked 56 species by total percentage loss and found that small, oily, fast-spoiling pelagics fared worst. Sardines topped the table at 13.8 percent total loss, translating to an average monetary loss of 31.61 OMR per fisher, followed by yellowfin tuna at 12.4 percent and longtail tuna at 11.2 percent. Indian mackerel and mahi-mahi rounded out the top five. Shrimp, though only sixth by percentage at 10.7 percent, suffered the highest average monetary loss of any species at 63.69 OMR, a consequence of its exceptional market value combined with its biochemical vulnerability to autolysis and melanosis, the enzymatic self-digestion and dark-spot discoloration that rapidly degrade crustacean flesh. The pattern reflects well-understood food science: polyunsaturated fatty acid-rich small pelagics oxidize quickly at high ambient temperatures, while histidine-rich species such as tuna and mahi-mahi risk histamine accumulation when chilling is delayed, a food-safety hazard as well as an economic one.

Why does so much value evaporate between net and auction? The fishers’ own rankings pointed first to high temperature, cited by 32.5 percent of respondents, and insufficient ice availability, cited by 31 percent, followed by long distances to landing sites and inadequate storage. Likert-scale items measuring perceived causes showed strong internal consistency, and analysis of variance confirmed that the causes differed significantly in their perceived severity. Direct exposure to sunlight drew 89.2 percent agreement, prolonged gear setting and hauling 85.8 percent, and long distances to landing sites 84.2 percent. Spearman correlation analysis revealed coherent clustering among these factors: poor handling during unloading correlated strongly with prolonged unloading times and inadequate storage, while cold-chain failures such as missing ice boxes and improper ice-to-fish ratios interlocked with transport and logistical constraints, painting a picture of systemic vulnerability rather than isolated mistakes.

To move beyond perception, the researchers fitted an ordinary least squares regression with nineteen explanatory variables spanning socio-demographics, fishing operations, preservation practices, and marketing conditions. The model explained a remarkable 81 percent of the variance in daily losses. Insufficient ice during transportation emerged as the strongest positive predictor, adding 46.55 OMR to daily losses when present. Conversely, preserving fish with ice on board the vessel cut losses by 32.81 OMR, and participation in post-harvest handling training reduced losses by 25.17 OMR. Market dynamics mattered too: each additional day required to sell the catch added 23.87 OMR in losses, and every extra kilogram of unsold fish, which averaged 10 kilograms per day, cost another 1.46 OMR daily. Notably, 70 percent of fishers reported insufficient ice during transport, largely because ice melted rapidly in the region’s heat, and 91.7 percent reported price fluctuations driven by supply-demand imbalances.

The socio-demographic signals were more nuanced. Older fishers tended to lose more per day, while higher educational attainment, larger household size, greater fishing experience, and full-time occupation were each associated with lower losses, though monthly income and access to bank loans showed no significant effect. The authors interpret these associations cautiously given the moderate sample size, emphasizing that they are correlational rather than causal. Still, the pattern aligns with a growing international literature: studies in Bangladesh, Ethiopia, Nigeria, Zambia, Ghana, and Malawi consistently find that education, experience, and training buffer against losses, while inadequate ice and cold storage amplify them. In Bangladesh, small-scale fisher losses reach 17.75 percent; in Kenyan Lake Victoria, artisanal fishers report total losses of 31 percent. Oman’s species-level losses of roughly 2 to 14 percent appear moderate by comparison, but the high absolute monetary value of the daily losses underscores how much revenue is at stake in a sector that produced 869,968 metric tons, about 95 percent of Oman’s 2021 landings, from small-scale operations.

The study’s diagnosis of infrastructure gaps is grounded in direct field observation. Assessments at As Seeb, Muttrah, and Qurayyat revealed inadequate insulated storage capacity, scarce ice supply points, a shortage of sheltered unloading areas, limited refrigerated transport to retail halls, and few processing facilities. Waste management systems showed limited capacity to recover fish by-products. The authors argue that Oman’s expanding artisanal landings have outpaced investment in cold-chain infrastructure, ice supply, and processing capacity, particularly at decentralized landing sites, echoing earlier work on the country’s fisheries development. When fish sit in queues under the sun awaiting unloading, or travel uninsulated in motorized cargo tri-cycles to auction halls, microbial and biochemical degradation accelerates, freshness declines, and auction prices fall, sometimes triggering outright rejection of fish with belly rupture, mechanical damage, or severe odor.

When asked to rank solutions, fishers put adequate ice facilities first at 40.8 percent, followed by improved storage facilities on boats at 33.5 percent, faster transportation, modern fishing gear, and refrigeration at landing sites. The authors translate these priorities into a multi-stakeholder framework aligned with Oman Vision 2040 and the United Nations Sustainable Development Goals. Government agencies would lead investment in ice plants, insulated storage, and unloading shelters; fisher cooperatives would manage shared facilities and coordinate auction timing; academic institutions and vocational institutes would deliver handling and cold-chain training; and microfinance institutions would finance insulated containers and small refrigeration units for fishers who cannot otherwise afford them. The framework distinguishes between smaller operators, who might benefit from subsidized input packages and localized extension services, and larger-scale fishers who need integrated cold-chain systems and better market access. Complementary non-infrastructure measures include selective fishing gears to reduce mechanical injury, value-addition through drying, salting, smoking, and freezing to absorb unsold fish, and by-product recovery for fishmeal or fertilizer in line with circular economy principles.

What makes this study significant beyond Oman is its methodological rigor in a data-poor region. Post-harvest loss assessments remain scarce across the Arabian Peninsula, and the combination of load tracking, auction price validation, and regression modeling offers a template that other Gulf and Indian Ocean fisheries could adopt. The authors call for future research extending into transport vehicles and retail markets, where losses likely continue to accumulate after the auction hall. For now, the message from Muscat’s landing sites is clear: the gap between a thriving catch and a thriving income is measured largely in degrees Celsius and kilograms of melting ice, and closing it will require coordinated investment in cold-chain infrastructure, human capital, and market systems rather than any single technical fix.

Subject of Research: Post-harvest fish losses and their determinants among small-scale fishers at landing sites in Oman

Article Title: Post-harvest fish losses among small-scale fishers in Oman: Magnitude, determinants, and mitigation priorities

Article References: Post-harvest fish losses among small-scale fishers in Oman: Magnitude, determinants, and mitigation priorities. (n.d.). https://doi.org/10.1016/j.indic.2026.101532

Image Credits: AI Generated

DOI: 10.1016/j.indic.2026.101532

Keywords: post-harvest fish losses, small-scale fisheries, Oman, cold chain, ice supply, food security, artisanal fishing, fish spoilage, auction markets, fisheries economics, OLS regression, Oman Vision 2040