Effect of Treated Wastewater from Anaerobic Digester Coupled with Anaerobic Baffled Reactor as Fertigation on Soil Nutrient Residues, Growth and Yield of Maize Plants

Water scarcity, wastewater management and growing food demand associated with global population increase, are among the drivers cited for water reuse in agriculture. The current study intends to contribute on the influence of treated wastewater from the anaerobic digester coupled with anaerobic baffled reactor (ABR) as a fertigation on soil nutrient residues, growth and yield attributes of maize plants by using surface drip irrigation system to apply the treated wastewater. The experiment consisted of experimental plots irrigated with treated wastewater and control plots irrigated with tap water; all with three replications. The treated wastewater was lightly alkaline with pH of 7.8±0.2 and high concentration of nutrients than tap water, but were within the acceptable levels. Fertigation with treated wastewater improved soil fertility evidenced by significant improvement (P≤0.05) in plant height, leaf area Index (LAI) and maize yield. Plant height was 1.5 times taller and LAI was about 2.5 times more in treatment than in control plots. Yield attributes in experimental plots including number of grains per cob, (97±11.3); weight of grains per cob, (80.7±7.9 g); mass of 100 grains, (35.0±3.5 g), and grain yield, (745.8±62.9 Kg/ha) were significantly higher (P≤0.05) compared to their counterpart control plots. The grain yield in experimental plots was about 37% higher than the yield in control plots. Therefore, fertigation with treated wastewater from the anaerobic digester coupled with ABR improves maize yield and is advisable in areas with water scarcity

Pilot-scale experiment on anaerobic landfill bioreactor in Tanzania

Landfill bioreactors have been developed in industrialized countries as a long-term municipal solid waste (MSW) management option, but in East Africa no landfills have yet been designed and operated as recirculated landfills or bioreactors. Treatment of leachate and landfill gas emanating from landfilling remains a major environmental concern despite improved techniques of landfilling of solid wastes. This paper presents findings from a comparative study of a pilot scale landfill bioreactor and sanitary landfill conducted in Dar es Salaam city, Tanzania, to study the effect of leachate recirculation on waste degradation and acidification, landfill gas production, and in situ leachate treatment to provide insights for the successful operation of landfill bioreactors in developing countries. Two reactors R1 and R2 were built and each filled with about 2.3 tons of wet waste predominantly food waste (about 60%) of moisture content about 64% collected from municipal waste transfer stations. R1 was operated as a control reactor simulating a sanitary landfill and R2 was a simulated landfill bioreactor (LFB). Throughout the study of 52 weeks R1 was run as a flow through system whereas R2 was broken into two phases. During phase one of R2 the leachate was recirculated directly to the top of the reactor and phase two involved recirculation of leachate after treatment via an Up-flow Anaerobic Sludge Blanket reactor as an in-situ pre-treatment measure of the leachate. The study revealed that acidification of the leachate in the LFB without production of landfill gas (LFG) during a certain period is possible and that the LFB can be used for the first two steps of anaerobic digestion (i.e. hydrolysis and acidification) and then the remaining step of methanogenesis can be carried out in a separate reactor to produce biogas at a shorter period. The study also showed that biogas production in the reactor with recirculation of leachate strongly increases the total biogas production compared to the reactor with no recirculation of leachate. Overall, this study indicated the feasibility of operation of the LFB with waste characteristics of Tanzania to accelerate the stabilization of organic-rich wastes, enhance LFG production and achieve a degree of leachate treatment.Keywords: Landfill Bioreactor, anaerobic digestion, leachate, landfill ga