Co-Composting of Khat-Derived Biochar with Municipal Solid Waste: A Sustainable Practice of Waste Management

Abstract

Biochar is a way to improve the performance of the composting process and the quality of compost. This study was aimed to investigate the optimum ratio of khat straw (Catha edulis) biochar and organic municipal solid waste mixtures to improve the quality of the resulting co-composts. Khat-derived biochar during pyrolysis at 350 °C was added to organic municipal solid waste mix and four co-composting treatments were prepared with the compositions (% w/w): control compost (no biochar) and 5%, 15%, and 25% co-composted biochar in three replicates. The total organic carbon, organic matter, total nitrogen, available phosphorus, and potassium values ranged as 16.76–21.45%, 30.77–40.26%, 0.97–1.68%, 0.58–0.76%, and 12.72–15.29%, respectively. The results confirmed that 5% and 15% co-composted khat biochars had significantly reduced (p < 0.05) organic matter loss and increased the contents of cation exchange capacity, pH, phosphorous, potassium, calcium, magnesium, and zinc compared to the control compost, while some heavy metals (Fe, Cu, and Mn) and EC values in co-composted biochars are lower than the control compost. Khat-derived biochar could be added to municipal organic waste mix at 5–15% (w/w) in order to get better quality of compost, which can be used as biofertilizer.

Effect of forest-based biochar on maturity indices and bio-availability of heavy metals during the composting process of organic fraction of municipal solid waste (OFMSW)

“…At the end of the composting process, the C content of the piles containing 15% and 25% biochar were measured as 19.38% d.m. and 21.45% d.m., respectively 3 , which is similar to the trend seen in the present study.…”

“…In the cooling stage, mesophilic bacteria start to work again and in the last stage (compost maturation stage), actinomycetes, molds and some fungi appear 38 . Specifically, an excessive and continuous increase in temperature (typically more than 65 degrees Celsius), leads to a decrease in the population of beneficial microorganisms and, as a result, a decrease in the speed of the composting process 3 and a decrease in temperature leads to a decrease in the activity of effective microorganisms and the reduction of production efficiency will occur 18 . It is very necessary and vital that during the active stage of industrial composting, the temperature is kept within the range of activity of thermophilic bacteria so that pathogens and weed seeds are destroyed.…”

“…Many methods have been developed to dispose of the organic fraction of municipal solid waste (OFMSW). Composting is one of the most popular methods of recycling the OFMSW 3 . Compost production from OFMSW is conducted to reduce the volume and weight of disposable materials, decrease the smell and leachate, recycle resources, and mitigate potential disposal costs 4 , 5 .…”

Assessing the Potential of Teff Husk for Biochar Production through Slow Pyrolysis: Effect of Pyrolysis Temperature on Biochar Yield

“…These findings were attributed to the rapid release of volatile compounds during pyrolysis at higher temperatures. The results obtained in this study align closely with previous research [12,57,69,70], which investigated the impact of pyrolysis temperature on biochar porosity and pore size using SEM and BET analysis simultaneously. It has been found that the pyrolysis reaction obtained in this study closely matches the results of Landrat et.…”

Short term effects of Municipal Solid Waste compost, Khat-Derived Biochar and Co-composted Biochar on Soil quality and Faba bean Yield and Protein content

“…i.e i) control compost mix (no biochar), ii) 5% co-composted biochar (95%w/w organic waste mix + 5% w/w biochar), iii) 15 % co-composted biochar (85% w/w organic waste mix + 15% w/w biochar), iv) 25% co-composted biochar (75% w/w organic waste mix + 25% w/w biochar). The physico-chemical properties of amendments were showed in Table 1 30 .…”