Treatment of municipal solid waste landfill leachate by use of combined biological, physical and photochemical processes

Abstract

a b s t r a c tThe purpose of this work was to study the treatment of a leachate coming from the municipal solid waste landfill of Astana (Kazakhstan). Physical (striping and adsorption), biological and photochemical processes were applied separately or in combination, and the treatment efficiency was attended in terms of carbon and nitrogen removal. The leachate carbon was by 45%-60% inorganic while nitrogen was almost 100% inorganic in the form of ammonia. The results showed that inorganic carbon and ammonia can be almost entirely removed by air stripping at pH = 7 and pH = 12, respectively. The removal of organic carbon by stripping alone was lower than 4% but combined to adsorption reached 20%, and to biological treatment 30%. The removal of organic carbon by photochemical oxidation alone was 43%. The combination of stripping, adsorption and biological treatment resulted in 37% organic carbon and with the addition of photochemical oxidation step the removal was increased to 59%. In overall, total carbon removal reached 85% and total nitrogen removal almost 100%. The results showed that the decomposition of landfill leachate carbon is a challenging task requiring a combination of processes. On the contrary, as almost all nitrogen is inorganic, air stripping at elevated pH alone can sufficiently eliminate it.

Survey on Household Solid Waste Sorting at Source in Developing Economies: A Case Study of Nur-Sultan City in Kazakhstan

“…However, the environmental impacts are manifold, such as, for instance, the continuous methane emissions and groundwater contamination due to leachate discharge [7,8]. Currently, about 95% of HSW in Kazakhstan is disposed into sanitary landfills, while the entire volume of HSW placed in landfills is estimated to be over 100 Mt [1,9]. The approximate annual production is 4-5 Mt, whereas by 2030 this number is expected to grow up to 7 Mt [10,11].…”

Effective photochemical treatment of a municipal solid waste landfill leachate

“…Conductivity was measured with a digital EC meter (Five Easy™ FE30). Leachate TSS (Total Suspended Solids) were measured by filtering under vacuum 20 mL of sample through a 1.2 μm glass fiber filter paper, and TS (Total Solids) measurement was conducted by placing 45 mL of sample in a beaker heated at 105˚C in an oven for 24 h [44]. All measurements were conducted at least twice for three samples.…”

“…Moreover, ammonia present at concentrations up to about 2000 mg L -1 in leachate can be toxic to microorganisms and inhibit biological treatment processes [4]. As a result, a pretreatment process was applied in two stages [44]: firstly, ammonia was eliminated by applying air stripping for 24 hours at pH = 12, and…”

“…Prior to the photochemical treatment, the pretreated leachate was mixed with tap water at a ratio of 5/12 (volume basis) [44]. The initial carbon concentration of the pretreated diluted leachate was in the range of 1200±100 mg L -1 with all carbon coming from organic compounds, while its total nitrogen was 150±24 mg L -1 and pH in the range of 5.1-5.3.…”

“…An annular photoreactor with 56.8 mL of active volume operated in batch recycle mode was used for photochemical experiments. The solution was continuously pumped at the rate of 178 mL min -1 through the photoreactor using a peristaltic pump (Heidolph 5006) [44]. An Osram lamp with 6 W power, located inside the photoreactor, emitted UV irradiation of 254 nm.…”