Multiple wastes' co-digestion is one of the alternatives for improved anaerobic digestion (AD) process of industrial and municipal wastes. The present work investigated the influence of fruit-vegetable solid waste (FVW) addition as a co-substrate on the performance of AD of abattoir wastewater (AWW). The co-digestion was done at a lab-scalebased experiment under mesophilic condition using a two-phase anaerobic sequencing batch reactor without agitation. It was tested at different mixing ratios (100%AWW; 75%AWW:25%FVW; 50%AWW:50%FVW; 25%AWW:75%FVW; 100%FVW) with the intention of looking for the best mixing ratio with the best performance. It was fed on a semicontinuous basis and operated for 18 days (d) total retention time (HRT): 3 days for the acidogenesis reactor and 15 days for methanogenesis reactor. The addition of FVW enhanced biogas yield and VS removal by 70.26% and 57.11%, respectively, at optimum mixing ratio. Moreover, to some extent improvement of AD process stability verified by the decreased TVFA:TAlk ratio and free ammonia nitrogen was observed upon progressive addition of FVW. Finally, this co-digestion process should further be studied for its performance at different HRTs with agitation.

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Biochar has gained an attention in reducing the bio-availability of toxic heavy metals and minimize threat of entering into food chain from contaminated soil. This study was aimed at evaluating the potential use of brewery sludge biochar (BSB) as a soil amendment for reducing cadmium bio-availability and uptake by Brassica carinata in a pot experiment. In this pot experiment, artificially cadmium spiked, moderately fertile, and slightly basic silty-loam soil was used. The biochar was produced by pyrolyzing of the brewery sludge at 500 °C. The obtained biochar was sieved with 0.5 mm mesh size and applied at the rate of 4 % (w/w) on the Brassica carinata grown cadmium spiked soil. The additions of BSB to the soil contributed a significant reduction of the bio-availability of cadmium in the soil and its accumulation in the shoot of Brassica carinata by 86% and 93%, respectively. Besides, it remarkably increased the dry weight of the edible part of Brassica carinata by 228% . The results revealed that BSB is very effective additive in cadmium immobilization, in turn, significantly (p-value = 0.00) promoting vegetable ( Brassica carinata ) growth. Therefore, BSB can be used as agricultural soil remedy for cadmium contamination and as safe disposal of brewery sludge.