Mixture Of Leachate Research Articles

Pilot-scale models of treatment of landfill leachates combined with urban wastewaters in a facultative lagoon

This study set out to determ ine the potential for treating leachates in combination withwastewater at Facultative Lagoons, a device normally used for treating raw wastewaters.Pi lot-scale models were used to simulate leachate treatment and disposal in a FacultativeLagoon (FL), combining 2.4 L/hr of raw wastewater with a leachate m ixture (comprising bothyoung and old leachates), in concentrations of 4%, 6%, and 1 0% (v/v). The solution ofleachate mixture in raw wastewater was then fed into the two pilot-scale models (MI andM2). The fol lowing parameters : concentration of algae; chlorophyll a, b and c; faecalcoliforms (FC); and heavy metals, were analyzed in all the three component stages: theunmixed wastewater; the old and young leachate mixture; and the combined wastewaterleachate mixture.As a 1 0% di lution was found not to impede correct functioning of the Model FacultativeLagoon, the same concentration was tried out using urban wastewaters from the UniversityWastewater Treatment Plant (UWTP).Interval values of BODs and COD in the wastewater and in the leachate mixture were 45-875mg/L and 307-5,763 mg/L respectively, and results showed that a I 0% concentration ofleachates combined with wastewater does not upset the system of biological treatment. Noneof the m ixtures affected the population of algae. Maximum removal efficiency of BOD5 was75%, and 35% for COD, therefore leav ing a BOD5 level of less than 25 mg/L in the efflouentfrom the FL. The removal of BOD5 and COD from the U WTP was greater still, 86% and64%, respectively. FC and heavy metal concentrationso: As (0.007 mg/L), Cd (0.02 mg/L), Cu(<0.0 l mg/L), Cr ( 0.04 mg/L), Hg (o<0.00027 mg/L), Ni ( 0.15 mg/L), Pb (0.098 mg/L), CN(0.02 13 mg/L) and Zn (0.05 mg/L), were all below the maximums establ ished by the MexicanFederal Regulation for Re-use of Wastewater in Agricultural Irrigation (NOM-ECOL-00 1 -1 996).

Treating leachate mixture with anaerobic ammonium oxidation technology

Large amounts of ammonium and a low content of biodegradable chemical oxygen demand(COD) are contained in leachate from aged landfills, together with the effluent containing high concentration of nitric nitrogen after biochemical treatment. Treatment effect of anaerobic ammonium oxidation (anammox) process on the mixture of the leachate and its biochemical effluent was investigated. The results show that the average removal efficiencies of ammonium, nitric nitrogen and total nitrogen are 87.51%, 74.95% and 79.59%, respectively, corresponding to the average ratio of removed nitric nitrogen to ammonium, i.e. 1.14 during the steady phase of anammox activity. The mean removal efficiency of COD is only 24.01% during the experimental period. The demand of total phosphorous for the anammox process is unobvious. Especially, the alkalinity and pH value of the effluent are close to those of the influent during the steady phase of anammox activity. In addition, it is demonstrated that the status of the anammox bioreactor can be indicated by the alkalinity and pH value during the course of the experiment. The anammox bioreactor has shown potential for nitrogen removal in the leachate mixture. However, COD and total phosphorous in the leachate mixture need further treatment for removal efficiencies of COD and total phosphorous are not good in the anammox bioreactor.

Struvite precipitation from anaerobically treated municipal and landfill wastewaters

A two-stage treatment system including upflow anaerobic sludge blanket reactor pre-treatment combined with a chemical post treatment system such as magnesium ammonium phosphate (MAP) precipitation was proposed as a comparable alternative to conventional biological treatment. In this study, anaerobically pre-treated domestic wastewater, domestic wastewater mixed with 2% and 3% of leachate by volume and raw leachate were further treated chemically with MAP precipitation. MAP precipitation was both applied at the stoichiometric ratio (Mg:NH4=PO4; 1:1:1) and above the stoichiometric ratio (1.1:1:1 and 1.1:1:1.1) on domestic wastewater + 3% leachate mixture. Maximum NH4-N removal of 68% was achieved at the pH of 9.2 at the stoichiometric ratio, whereas at the same pH value 70 to 72% NH4-N removal was obtained above the stoichiometric ratio. Additional ammonia recovery studies were conducted on Fenton's oxidation applied effluents before MAP precipitation and no significant additional ammonium removal was achieved. However, by the application of Fenton's oxidation high additional COD removals were obtained. Consequently, chemical treatment by MAP precipitation and/or Fenton's oxidation after anaerobic treatment yielded very effective removals for COD and NH4-N in domestic wastewaters + leachate mixtures.

Toxic effect of sulfur compounds on anaerobic biogranule

The effects of sulfide, sulfite and sulfate on degradation of volatile fatty acid (VFA) in UASB process have been studied by using serum bottle assay and septage–leachate acclimated biogranules. The relative toxicity of the compounds towards methane production and degradation of total VFA varied as SO 4 2−S>S 2−>SO 3 2−S and SO 4 2−S>SO 3 2−S>S 2−, respectively. The difference of this order shows the importance of choosing monitoring factor in evaluating the effect of sulfur compounds on a UASB system. For the individual VFA the effects of sulfur compounds depended on the types of VFA. The VFA-degrading activity of anaerobic biogranules was decreased by 50% when 34, 26 and 20 mg of S 2−, SO 3 2−S and SO 4 2−S were added to each gram of biomass, respectively. A comparison of the toxicity-resistance between two different anaerobic biogranules that acclimatized with septage–leachate mixture and septage was also made. In the presence of the leachate, the toxicity-resistance of biogranules was not weakened to sulfide and sulfate but was enhanced to sulfite.

Physical-chemical treatment of landfill leachate for metals removal

A detailed treatability study investigating metals removal from leachates collected from a sanitary landfill is presented. Experiments investigated treatment of raw leachate from younger and older zones of the landfill and of a mixture of the two leachates (representing an average leachate from the landfill). The metal concentrations and COD in leachate from the older area were approximately one order of magnitude greater than in leachate from the active area. The leachates contained significant quantities of reduced iron and manganese that, upon aeration and base addition, were precipitated and served as sorbents for trace metals that were present at much lower concentrations. Most trace metals in the younger zone leachate and in the leachate mixture were removed by adjusting solution pH to 9.0, but in leachates collected from the older landfill area, even raising the pH to 11.0 did not remove all the trace metals efficiently. Various options for treating a blend of leachate from the older and younger areas (20%:80% by volume) were evaluated. One of the key design decisions was whether to aerate the leachate prior to pH adjustment. Trace metals could be removed efficiently from the leachate with or without aeration. Benefits of aeration include increased formation of iron oxide adsorbent and a significant reduction in the amount of base required to raise the pH, since aeration strips large amounts of CO 2 from the leachates. Drawbacks include decreased sludge settleability and the cost of the aeration process itself. The settleability of the aerated sludge could be increased 5–10 fold by the addition of anionic polymer. Sludge produced was not toxic as determined by TCLP. Trade-offs implicit in these results are addressed both experimentally and theoretically.

Application of boron isotopes for identifying contaminants such as fly ash leachate in groundwater

The B isotopic ratio of a fly ash leachate can be very different from the B isotopic ratio of a natural groundwater. Mixtures of leachate and groundwater typically result in nonlinear B isotope mixing curves that enable identification and quantification of leachate contamination in a groundwater at much lower levels than possible using concentration analyses alone. Limits on B isotope use for contaminant quantification will exist for some environments such as landfills with multiple ash types, but B isotopic analysis may often remain the preferred method for qualitative identification. 20 refs., 4 figs., 3 tabs.