Leachate Quality Research Articles

An innovative coupling between column leaching and oxygen consumption tests to assess behavior of contaminated marine dredged sediments

Contaminated dredged sediments are often considered hazardous wastes, so they have to be adequately managed to avoid leaching of pollutants. The mobility of inorganic contaminants is a major concern. Metal sulfides (mainly framboïdal pyrite, copper, and zinc sulfides) have been investigated in this study as an important reactive metal-bearing phase sensitive to atmospheric oxygen action. An oxygen consumption test (OC-Test) has been adapted to assess the reactivity of dredged sediments when exposed to atmospheric oxygen. An experimental column set-up has been developed allowing the coupling between leaching and oxygen consumption test to investigate the reactivity of the sediment. This reactivity, which consisted of sulfide oxidation, was found to occur for saturation degree between 60 and 90 % and until the 20th testing week, through significant sulfates releases. These latter were assumed to come from sulfide oxidation in the first step of the test, then probably from gypsum dissolution. Confrontation results of OC-Test and leachate quality shows that Cu was well correlated to sulfates releases, which in turn, leads to Ca and Mg dissolution (buffer effect). Cu, and mostly Zn, was associated to organic matter, phyllosilicates, and other minerals through organo-clay complexes. This research confirmed that the OC-Test, originally developed for mine tailings, could be a useful tool in the dredged sediment field which can allow for intrinsic characterization of reactivity of a material suspected to readily reacting with oxygen and for better understanding of geochemical processes that affect pollutants behavior, conversion, and transfer in the environment.

Chemical quality of leachates and enzymatic activities in Technosols with gossan and sulfide wastes from the São Domingos mine

Purpose Sao Domingos mine area (Portuguese Iberian Pyrite Belt) contains several mine wastes with different environmental hazard which are disposed irregularly over a large area. This study aimed to evaluate the following: (1) soil enzymatic activities, chemical quality of leachates and Cistus ladanifer germination in Technosols composed of gossan or sulfide wastes from the mine and amendment mixtures (organic and inorganic); (2) the efficiency of a layer of gossan over sulfide wastes to improve rehabilitation of the more hazardous waste.

Leachate Treatment Using Aged Refuse (AR) as a Biofilter Medium

The uncontrolled formation of leachate during a waste-disposal process has become a serious issue in landfill management. An innovative filtration process for treating leachate by using aged refuse as a medium in biofilter has been studied recently. The aim of this study is to treat leachate by using aged refuse varied by years (4, 8, and 11 years) as a biofilter medium. To achieve the target, a few objectives were listed: i) to construct the biofilter system in a laboratory scale, ii) to explore the use of aged refuse (AR) as a biofilter medium to treat leachate from the selected landfill in Malaysia, and iii) to assess the quality of leachate treated with different aged refuse regarding physical properties, chemical properties, and microbe activity. Results showed that the initial concentration of leachate parameters is: i) chemical oxygen demand (COD) was 981.47 mg/L, ii) biochemical oxygen demand (BOD) was 527.16 mg/L, and iii) ammonia-nitrogen (NH3-N) was 2,815.56 mg/L and iv) bacterial count is 3.3×106 CFUs. After treating with aged refuse, the quality of leachate is increased based on the concentration reduction of COD, BOD, and N H3-N in the range of 30% to 49%, 17% to 48%, and 68% to 92%, respectively.

Effect ofMunicipal Solid Waste (MSW) depth on leachate quantity and quality

Effect ofMunicipal Solid Waste (MSW) depth on leachate quantity and quality

The release of As, Cr and Cu from contaminated soil stabilized with APC residues under landfill conditions

The aim of this study was to investigate the stability of As, Cr and Cu in contaminated soil treated with air pollution control residues under landfill conditions. The influence of landfill gas and temperature on the release of trace elements from stabilized soil was simulated using a diffusion test. The air pollution control residues immobilized As through the precipitation of Ca–As minerals (calcium arsenate (Ca5H2(AsO4)3 × 5H2O), weilite (CaAsO4) and johnbaumite (Ca5(AsO4)3(OH)), incorporation of As into ettringite (Ca6Al2(SO4)3(OH)12 × 26H2O) and adsorption by calcite (CaCO3). The air pollution control residues generally showed a high resistance to pH reduction, indicating high buffer capacity and stability of immobilized As in a landfill over time. Generation of heat in a landfill might increase the release of trace elements. The release of As from stabilized soil was diffusion-controlled at 60 °C, while surface wash-off, dissolution, and depletion prevailed at 20 °C. The air pollution control residues from the incineration of municipal solid waste immobilized Cr, indicating its stability in a landfill. The treatment of soil with air pollution control residues was not effective in immobilization of Cu. Contaminated soils treated with air pollution control residues will probably have a low impact on overall leachate quality from a landfill.

循環式準好気性埋立における循環浸出水の曝気効果に関する基礎研究（その４）-曝気浸出水の循環に伴う属レベルの細菌群集構造の変化とその要因-

循環式準好気性埋立における循環浸出水の曝気効果に関する基礎研究（その４）-曝気浸出水の循環に伴う属レベルの細菌群集構造の変化とその要因-

Landfill Gas Detection in Leachate Pipe: A Consideration for Design Improvement of Leachate Piping and Gas Venting Systems

Landfill provides simple and economic means of solid waste disposal. However, it causes negative effects to the environment due to leachate generation and greenhouse gas emissions. Current trends in landfill design allow aerobic or semi aerobic processes to take place inside the landfill to speed up degradation process and reduce odour. In Malaysia, the semi aerobic system of landfill design is adopted. This paper presents the study of the gas venting system and leachate quality of the semi aerobic landfill. The gas samples were collected from the end of the leachate pipe and the gas vent of a sanitary landfill by the water displacement method. Raw leachate samples from the landfill leachate ponds were collected and the COD of the samples were measured. The concentration of methane gas escaping from the leachate pipe was found to be around 13%. The COD content of the raw leachate was found to be more than 15000 mg/l. The improvement of landfill gas collection in Malaysia is recommended.

Effect of moisture control and air venting on H2S production and leachate quality in mature C&D debris landfills.

The effect of air venting and moisture variation on H2S production and the leaching of metals/metalloids (arsenic, copper, chromium, and boron) from treated wood in aged mature construction and demolition (C&D) debris landfills were examined. Three simulated C&D debris landfill lysimeters were constructed and monitored, each containing as a major debris component either wooden pallets, chromated copper arsenate (CCA) treated wood, or alkaline copper quaternary (ACQ) treated wood. The lysimeters were operated with alternating periods of water addition (a total of 160 L in four equal amounts) and air venting (68.4 m(3)per day for 121 days in two phases). Moisture addition did not increase H2S levels in the long term, and a significant drop in H2S concentration was observed (up to 99%) when aerobic conditions were promoted through air venting. H2S concentrations increased after venting stopped up to values approximately two orders of magnitude lower than observed prior to venting. Venting had the immediate consequence of suppressing biological H2S production, and the longer-term effect of decreasing organic matter that could otherwise be utilized in this process. Under aerobic conditions, the levels of arsenic, chromium, and boron in leachate decreased up to 96%, 49%, and 68%, respectively, while copper was found to increase up to 200% in CCA and 445% in ACQ column leachates.

Treatment of leachate by recirculating through dumped solid waste in a sanitary landfill in Addis Ababa, Ethiopia

In order to study the effect of leachate recirculation on the quality of leachate and as an in-situ ammonia–nitrogen removal mechanism, two polyvinyl chloride pipes compacted with a similar raw material composition and working with 4mL/min and 8mL/min leachate recirculation flow rate were continuously operated for nine consecutive weeks. In this laboratory scale study, wastewater quality indicator parameters including TS, BOD5, and two selected heavy metals Pb and Cu were used. To this end, the raw material characterization data indicates that all the materials compacted in the reactor were suitable for recirculation of leachate. We found 84.32% BOD5, 82.24% TS, 88.97% COD, 79.2% NH4+–N and 94% Cu removal efficiency that was operated at 4mL/min in R1 and 66.45% BOD5, 75% COD, 62.98% TS, 67.47% NH4+–N and 79.32% Cu achieved removal efficiency at 8mL/min in R2. The overall study indicates that leachate recirculation can serve as an in-situ treatment of leachate, even for ammonia nitrogen removal and old landfill leachate, if the working conditions are maintained in appropriate manner.

Comparison of Solid Waste Stabilization and Methane Emission from Anaerobic and Semi-Aerobic Landfills Operated in Tropical Condition

Leachate quality and methane emission from pilot-scale lysimeters operated under semi-aerobic and anaerobic conditions were monitored for 650 days. Two semi-aerobic lysimeters were filled with un-compacted and compacted municipal solid wastes whereas two anaerobic lysimeters containing compacted wastes were operated with leachate storage at 50% and 100% of waste height, respectively. Despite having high moisture in wastes and operating under tropical rainfall events, leachate stabilization in semi-aerobic lysimeters took place much faster resulting in BOD reduction by 90% within 60 days, significantly shorter than 180?210 days observed in anaerobic lysimeters. Nitrogen concentration in leachate from semi-aerobic lysimeter could be reduced by 90%. In term of gas emission, semi-aerobic lysimeter with un-compacted wastes had much lower methane emission rate of 2.8 g/m2/day compare to anaerobic lysimeters (62.6 g/m2/day) through seasonal fluctuation was observed. Nevertheless, semi-aerobic lysimeter with waste compaction has similar performance to anaerobic lysimeter.

Spent Potassium Silicate Drilling Fluid Affects Soil and Leachate Properties

Potassium silicate drilling fluid (PSDF) is a relatively new type of drilling waste generated by the oil and gas industry. PSDF effects on soil, vegetation, and ground water must be determined before its land disposal and use in reclamation can be regulated. A laboratory column leachate study was conducted to quantify the response of select soil and leachate properties to PSDF at various depths in soil column profiles. A spent PSDF was applied to two soils (sand and loam textures) at four rates (20, 40, 60, 120 m3 ha−1) with two application methods (incorporated, sprayed). Changes to soil and leachate properties were at values that would not be detrimental to most plant species when PSDF was applied at ≤60 m3 ha−1. Applying PSDF at 120 m3 ha−1 had significant effects on soil properties and leachate quality. Hydraulic conductivity and field capacity were significantly reduced, and soil available potassium and sulfate concentrations, pH, and salinity increased with PSDF. Incorporated PSDF in the upper 10 cm of soil accelerated PSDF element transport through soil columns to leachate and increased organic carbon and salinity in leachate. PSDF application rate significantly reduced soil field capacity, available nitrogen, and increased salinity at the highest rates in loam soil, suggesting a threshold beyond which conditions will not be suitable for land spraying PSDF. This research demonstrates that PSDF has potential to improve soil short term water availability, macronutrient potassium and sulfur for disposal on cultivated and uncultivated lands. This potential should be field tested.

The potential impact of leachate-contaminated groundwater of an ex-landfill site at Taman Beringin Kuala Lumpur, Malaysia

Spreading of leachates to soil, surface and groundwater aquifers is a prevailing problem with unlined landfills, causing many problems with adverse impacts on the surrounding environment. The impact of leachate contamination on groundwater quality was investigated from unlined ex-landfill site at Taman Beringin in Malaysia to identify the characteristics of the groundwater, and the possible impacts on the environment. Various physico-chemical parameters including: temperature, pH, color, TDS, TSS, BOD, COD, S2−, F−, Cl−, NH3-N, \({\text{SO}}_{4}^{2 - }\), \({\text{NO}}_{3}^{ - }\), and heavy metals: Ag, As, Cd, Cu, Cr3+, Cr6+, Fe, Hg, Ni, Pb, Zn, Mn, B, Se, Sn and Ba, were collected from four (4) monitoring wells and six (6) surface raw leachate points between December 2012 and January 2013. Physico-chemical analyses of sampled leachates and groundwater followed standard analytical methods. The results showed considerable impact of leachates on groundwater with high concentration of most chemical parameters in groundwater samples: COD (101.75 ± 99.42), BOD (28 ± 30.99), NH3-N (31.10 ± 19.12), F− (0.72 ± 0.32) and heavy metal; Pb (0.042 ± 0.045), Ni (0.016 ± 0.006), Fe (0.41 ± 0.68) have exceeded the Malaysian National Drinking Water Quality Standard and National Water Quality Standards CLASS II A. Remedial measures are suggested to prevent further spreading of leachates into rivers via groundwater flow. In addition, combined process of routine chemical treatment prior to biological treatment is necessary to improve the existing leachate quality to minimize the effects on the surrounding environment.

Performance of vertical flow constructed wetlands for faecal sludge drying bed leachate: Effect of hydraulic loading

The discharge of raw faecal sludge directly into the environment is a common practice that threatens environmental and public health in low-income countries. Planted drying beds are a promising and low-cost option for treatment of faecal sludge and the production of fodder plants, but current research shows the leachate quality does not meet guidelines for discharge. This paper investigates the use of Vertical Flow Constructed Wetlands (VFCWs) planted with Echinochloa pyramidalis for polishing of leachate from faecal sludge drying beds. At a pilot-scale, three hydraulic loads (50, 100 and 150mm/d) were applied with single loadings once a week on VFCWs (corresponding to 31±9, 63±19, 94±28g/m2/month of BOD5; 21±6, 42±12, 63±19 TKN; and 2±1; 4±4; 6±6 PO4–P, respectively, for hydraulic loading rates of 50, 100 and 150mm/d). Infiltration flow rate, plant growth, rhizospheric bacteria, and leachate characteristics were monitored. VFCWs were effective in reducing on average more than 80% of the pollutants monitored (COD, BOD5, NH4–N, TKN, PO4–P, and faecal bioindicators), which met all National Cameroon and WHO guidelines for safe reuse in agriculture, except for total nitrogen and faecal indicators. Results confirmed a correlation between plant density and rhizospheric bacteria growth with increasing hydraulic load. These are important results, demonstrating that VFCWs can operate efficiently at multiple hydraulic loadings, and are hence adaptable to different sized treatment schemes. It also illustrates that if plant production for fodder is a goal, increased loading rates are preferable as they achieve overall treatment goals and result in greater plant production.

Field investigation of the quality of fresh and aged leachates from selected landfills receiving e-waste in an arid climate

The management of electronic waste (e-waste) is a serious problem worldwide and much of it is landfilled. A survey of four selected landfills in an arid region of South Australia was conducted to determine the proportion of e-waste in municipal waste and the properties of each landfill site. Leachate and groundwater samples were collected upgradient and downgradient of the landfills for analysis of polybrominated diphenyl ethers (PBDEs) and 14 metals and metalloids, including Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, V and Zn. Our data demonstrate that the selected landfills in South Australia continue to receive municipal waste containing in excess of 6%, or 25,000tonnes per year, of e-waste. The leachates and groundwater collected from the landfills contained significantly elevated concentrations of Pb with the highest concentration in groundwater of 38μg/l, almost four times higher than the Australian drinking water guideline of 10μg/l. The presence of PBDEs was detected in both leachate and groundwater samples. Total PBDEs values of 2.13–59.75ng/l in leachate samples were 10 times higher than in groundwater samples, which recorded a range of 0.41–6.53ng/l at all sites. Moreover, the concentrations of metals and metalloids in sampled groundwater contained elevated levels of Al, As, Fe, Ni and Pb that exceeded Australian drinking water guideline values. For these reasons potential leaching of these contaminants is of concern and while difficult to attribute elevated contaminant levels to e-waste, we do not recommend continued disposal of e-waste in old landfills that were not originally designed to contain leachates. The survey also revealed temporal variation in the electrical conductivity and concentrations of As, Cd and Pb present in leachates of landfills in arid Mediterranean climates. These results are consistent with the marked variations in rainfall patterns observed for such climates. The solute concentration (EC and other ions including As, Cd and Pb) declines in the leachates during wet winter months (June to September), in contrast to tropical countries where such changes are observed during wet summer months.

N2O emission from a combined ex-situ nitrification and in-situ denitrification bioreactor landfill

A combined process comprised of ex-situ nitrification in an aged refuse bioreactor (designated as A bioreactor) and in-situ denitrification in a fresh refuse bioreactor (designated as F bioreactor) was constructed for investigating N2O emission during the stabilization of municipal solid waste (MSW). The results showed that N2O concentration in the F bioreactor varied from undetectable to about 130ppm, while it was much higher in the A bioreactor with the concentration varying from undetectable to about 900ppm. The greatly differences of continuous monitoring of N2O emission after leachate cross recirculation in each period were primarily attributed to the stabilization degree of MSW. Moreover, the variation of N2O concentration was closely related to the leachate quality in both bioreactors and it was mainly affected by the COD and COD/TN ratio of leachate from the F bioreactor, as well as the DO, ORP, and NO3−-N of leachate from the A bioreactor.

Application of a partial nitritation and anammox system for the old landfill leachate treatment

This study shows high nitrogen removal efficiency of a combination of partial nitritation and Anaerobic Ammonium Oxidation (anammox) process for old landfill leachate treatment. A lab-scale experiment including partial nitritation using a sequencing batch reactor (PN-SBR) followed by a anammox hybrid reactor (HAR), which consists of suspended biomass layer in the bottom part and bio-carrier bed in the upper part run at the influent total ammonia concentrations (TAN) of 500 mg N/L and 1000 mg N/L. The result of PN-SBR experiment showed that the NO2–N:NH4–N ratio achieved about 1.22 and 1.02 at HRT of 12 h (influent TAN of 500 mg N/L) and HRT of 19 h (influent TAN of 1000 mg N/L), respectively. Simultaneously, the HAR was operated at the nitrogen loading rate (NLR) of 4.2 and 8.3 kg N/m3.d, corresponding to influent TAN of 500 mg N/L and 1000 mg N/L, respectively. The effluent of the system containing 9.7 ± 3.5 mg NH4–N/L, 1.7 ± 0.4 mg NO2–N/L and 23 ± 4 mg NO3–N/L (equivalent to 35 ± 4 mg TN/L) at NLR of 1.02 for PN-SBR and NLR of 4.2 kg N/m3.d for HAR. This effluent quality was good enough to meet Vietnamese treated landfill leachate quality. The system obtained TN removals of 93 ± 1% and 81 ± 1.2% at NLRs of 4.2 kg TN/m3.d (phase I) and 8.3 kg TN/m3.d (phase II), respectively. The total biomass of HAR including attached biomass and suspended one was maintained up to 20,400 mgVSS/L at the end of the experiment when the removal rate of anamnox biomass obtained 0.4 kg TN/kgVSS.d. While, PN-SBR was kept at 2300 mg MLVSS/L and SRT of 10–12 days at NLR of 4.2 kg TN/m3.d, which the nitrogen conversion rate of AOB was 0.53 kg TAN/kgVSS.d. In terms of COD removal, it is found that PN-SBR removed only 14% of influent COD, whereas HAR removed 30% of COD.

Leaching characteristics of poultry litter in first phase of multistage anaerobic digestion

Poultry litter is highly biodegradable in nature. Therefore, it could be subjected to biomethanation to produce valuable biogas and bio-manure as byproducts. Some studies have been conducted along these lines in India by utilizing the poultry litter as a substrate in batch type dung digesters of KVIC and DENABANDHU models. However, these reactors have the drawbacks of high residence time (30 – 35 days), scum formation problems etc. Moreover, these batch type plants are not suitable for the treatment of large quantities of solid waste. Multistage anaerobic digestion has the potential to overcome some of the aforesaid issues. Anaerobic leaching experiments were conducted at different total solids concentration and pH using poultry litter in order to evaluate the leachate quality for a period of 7 days. The increase in Total solids (TS) % from 15 to 20% show inverse effect on VFA and Alkalinity. The change in pH from 8.5 to 5.5 didn’t show much impact on VFA but there is a small impact on alkalinity. It was also observed that the leaching of the organic matter in the solid to the liquid phase is very fast and it is taking place approximately in three to four days and subsequently leachate getting saturated. Therefore, reactor set up was made in the last phase to regularly remove the water from the reactor so that higher driving force is available for leaching. The study resulted in leaching of maximum organic content in the solid to liquid within three days. DOI: http://dx.doi.org/10.3126/ije.v3i2.10516 International Journal of the Environment Vol.3(2) 2014: 76-82

Pretreated municipal solid waste behaviour in laboratory scale landfill

Mechanical biological pretreatment processes are increasingly being employed as a means of diverting biodegradable municipal waste from landfi ll to comply with the EU Landfi ll Directive. This will have major implications for the nature of the waste that is disposed of to landfi lls and hence for the way in which the landfi lls should be managed. The long-term behaviour of mechanically biologically treated (MBT) waste will be different from that of unprocessed municipal solid waste since the pretreatment process may change its physical, chemical and biological properties. To investigate the impact of the level of pretreatment, large-scale laboratory experiments were carried out on MBT wastes treated to typical UK and German standards. Gas generating potential, leachate quality, settlement characteristics and hydraulic properties of MBT wastes were determined and compared. The research has demonstrated the benefi ts of pretreatment in substantially reducing the gas generating potential, releasing low levels of total organic carbon and ammoniacal nitrogen and, reducing the long-term settlements due to creep and biodegradation. Data from both MBT wastes followed the same general trend of decreasing hydraulic conductivity and drainable porosity with increasing stress and waste density.

INVESTIGATING LEACHATE CONTAMINATION NEAR THE QUEZON CITY CONTROLLED DUMPING FACILITY (QCCDF) USING CHLORIDE ION AS INDICATOR

The Quezon City Controlled Dumping Facility (QCCDF) has been the main disposal site of Quezon City, the largest city within Metro Manila since the 1970s. With the huge volume of wastes received every day and with no protective liner on the old mound and creeks directly connecting the facility to Marikina River, the main river system in eastern Metro Manila, surface and groundwater contaminations have been a critical concern. The main objective of the study is to determine the effect of the disposal site on the surface water and groundwater quality by evaluating the water quality at different points in and around the landfill. Secondarily, it aims to investigate correlations between the water quality parameters as well as determine any seasonal effects on the water quality. Sampling points from wells on and around the facility were collected for six months covering dry and wet season using Horiba water quality monitoring equipment and CHEMetrics V-2000 Photometer. Leachate quality parameters pH, turbidity, DO, and chloride are not affected by the change in seasons as evidenced by statistical t-tests. Temperature is higher during the wet season, while TDS is lower at this time which may be attributed to dilution due to rainfall. DO and turbidity in leachate is strongly negatively correlated, while temperature and Clin leachate are positively correlated. In groundwater, the change in season affects temperature, TDS and chloride concentrations. This trend is not evidenced in pH and turbidity. TDS and chloride are correlated with each other. Based on the surface water quality measurements, temperature, pH, DO, and TDS are affected by the change in season while turbidity and chloride are not, based on the comparison of samples taken from different locations. Aside from strong correlation of Clˉ and TDS, as seen in groundwater, very strong correlations are also observed between Clˉ and DO, and TDS and DO. Using chloride ion as indicator of leachate, the study reveals that the leachate tends to spread downward towards Marikina River. Based on the comparison of chloride concentrations near the outfall of the leachate creek at Marikina River, it can be seen that the release of leachate at the river impacts the river as evidenced by an increase in chloride concentration downstream of the outfall.

Possible source term of high concentrations of mecoprop-p in leachate and water quality: impact of climate change, public use and disposal

Mecoprop-p herbicide is often found in wells and water abstractions in many areas around Europe, the UK inclusive. There is a growing environmental and public health concern about mecoprop-p herbicide pollution in ground and surface water in England. Reviews suggest that extensive work has been carried out on the contribution of mecoprop-p herbicides from agricultural use whilst more work needs to be carried out on the contribution of mecoprop-p herbicide from non-agricultural use. The study covers two landfill sites in Weaver/Gowy Catchment. Mecoprop-p herbicide concentrations in the leachate quality range between 0.06 and 290 μg l−1 in cells. High concentration of mecoprop-p herbicide in the leachate quality suggests that there is a possible source term in the waste stream. This paper addresses the gap by exploring possible source terms of mecoprop-p herbicide contamination on landfill sites and evaluates the impact of public purchase, use and disposal alongside climate change on seasonal variations in mecoprop-p concentrations. Mecoprop-p herbicide was found to exceed the EU drinking water quality standards at the unsaturated zone/aquifer with observed average concentrations ranging between 0.005 and 7.96 μg l−1. A route map for mecoprop-p herbicide source term contamination is essential for mitigation and pollution management with emphasis on both consumer and producer responsibility towards use of mecoprop-p product. In addition, improvement in data collection on mecoprop-p concentrations and detailed seasonal herbicide sales for non-agricultural purposes are needed to inform the analysis and decision process.