Potential use of solar energy for waste activated sludge treatment

The use of solar energy as a disintegration unit operation for waste activated sludge was tested in a pilot plant. The effect of the treatment process on chemical oxygen demand (COD), total suspended solids (TSS), settling time and filtration index was investigated in single (solar) and sequential processes (solar & biological). Solar oxidation was found to be a good sludge disintegration technology. Available solar photons were utilised to degrade the soluble organic matter and release the cell liquids. The highest COD and TSS removal efficiencies were obtained by the month of June. Sequential process efficiencies were related to accumulate solar photons, aerobic treatment time and operational condition. Sequential process resulted in COD and TSS removal efficiency of 16% and 13%, respectively. Increasing aerobic treatment time and/or mixing the oxidised sludge with fresh sludge improved COD and TSS removal efficiencies to 23% and 27%, respectively. The use of sequential processes improves the settling tendency of sludge by bio-oxidation of the released portions and eliminates protein charge effect on sludge settling.     

Experimental investigation of dust pollutants and the impact of environmental parameters on PV performance: an experimental study

The accumulation of dust pollution on the photovoltaic (PV) module can have a significant effect on the productivity and efficiency of PV systems in different locations in the world. Dust which accumulated over time on the PV module and is based on weather conditions led to the reduction in the effectiveness of solar cells. The aim of this research was to experimentally investigate the effect of the natural dust and the effects of environmental parameters on PV performance. The experiments were conducted to propose a model for the current, voltage, power and efficiency and to simulate the effect of environmental parameters on PV performance. The natural dust investigated consisted of different compounds: SiO₂ (45.53 %), CaO (24.62 %), Al₂O₃ (10.83 %), Fe₂O₃ (10.46 %), MgO (6.33 %), K₂O (0.87 %), TiO₂ (0.45 %), SO₃ (0.24 %), MnO₂ (0.21), Cr₂O₃ (0.23 %), SrO (0.13 %) and NiO (0.09 %). It was found that the most accurate correlation is a polynomial from seventh degree for current, voltage, power and efficiency, fourth degree for solar radiation and temperature, cubic degree for humidity and wind velocity. The coefficients of general model are 0.6343, 0.0110, 0.0 and 0.0001 for PV module, respectively, with 0.0011 fitting factor. The proposed model has been validated using models in the literature.     

Degradation of 17α-ethinylestradiol by ozonation--identification of the by-products and assessment of their estrogenicity and toxicity

The presence of the synthetic estrogen 17α-ethinylestradiol (EE2) in waters at low levels is a concern due to its ability to act as an endocrine disruptor. Ozone (O₃) is commonly used in water treatment and reacts with EE2 to form by-products having characteristics that are mostly unknown. The aim of this study was to identify the by-products of E2 and EE2 ozonation and determine their estrogenicity and toxicity relative to the parent compound. Ozonation by-products were identified via LC-MS analysis. The estrogenicity was measured using the YES assay, and toxicity was determined by monitoring effects on histology of fetal rat testes and testosterone secretion by these tissues. Two EE2 by-products were identified with open phenolic ring structures (masses 302 and 344 u). The Yeast Estrogen Screening (YES) assay showed a decreased but incomplete removal of estrogenicity after ozonation of EE2. Histological analysis of fetal testes revealed that neither E2 nor EE2, with or without ozonation, had any effect on seminiferous cord formation; however, a remarkable negative effect on testosterone secretion was observed, with EE2 by-products after ozonation showing the most rapid and extensive inhibition. These results show that the removal of EE2 via reaction with O₃ resulted in the formation of by-products that are less estrogenic (as demonstrated by the YES assay), but have a greater negative impact on testosterone secretion. Thus, the disappearance of the parent compound is not a sufficient endpoint, as the by-products created may be more toxic. Care should be taken when implementing oxidation applications such as ozone during waste water treatment.     

Inhibition of microbial activity of activated sludge by ammonia in leachate

Leachate samples were collected from the West New Territory Landfill (WENT), Hong Kong, and characterized in the laboratory. The analytical results confirmed that it has a typical nature of aged leachate with a low BOD₅/COD ratio of 0.22 and a high strength of ammonia-nitrogen around 5 g/L. A lab-scale study was conducted to investigate the inhibition of microbial activity of the activated sludge. In the first test, glucose-based synthetic wastewater was used in two parallel reactors. The experimental results demonstrated that COD removal declined from 95.1 to 79.1% and the dehydrogenase activity of the sludge decreased from 11.04 to 4.22 μg TF/mg mixed liquor suspended solids (MLSS), when the ammonia-nitrogen concentration increased from 50 mg/L to 800 mg/L progressively. The remaining NH₃⁺-N residue in the treated wastewater increased from 0.58 mg/L to 649 mg/L extensively. In the second test, mixed wastewater samples containing glucose and raw leachate were fed into six parallel biological reactors and operated on batch mode. The experimental results showed COD removal decreased from 97.7 to 78.1% and the dehydrogenase activity decreased from 9.29 to 4.93 μg triphenyl formazon (TF)/mg MLSS, respectively, when the ammonia-nitrogen concentration increased within the same range. Microbial inhibition could also be substantiated by a decrease of specific oxygen uptake rate (SOUR) from 68 to 45 mg O₂/g MLSS. These results suggested leachate containing high-strength ammonia-nitrogen should be pretreated to an acceptable NH₄⁺-N level before it is fed into biological reactors.     

Effects of short-term ozone exposure on net photosynthesis,dark respiration,and transpiration of three eastern white pine clones

Net photosynthesis, dark respiration, and transpiration rates were determined during ozone (O₃) exposure for three clones of eastern white pine (Pinus strobus L.) differing in sensitivity to O₃. Fumigations for 4 h with 0.10, 0.20, and 0.30 μL/L O₃ inhibited net photosynthesis of all three clones. Light transpiration was inhibited in both the sensitive and the tolerant clones and was not affected in the intermediate clone. Recovery of net photosynthesis and light transpiration occurred 1 h after the termination of ozonation, with the degree of recovery depending upon clonal sensitivity to O₃ and the O₃ concentration used. Dark respiration increased in the O₃-sensitive clone only, and dark transpiration was unaffected in all three clones after 4-h exposure to 0.30 μL/L O₃. Ozone-induced inhibition of net photosynthesis and stimulation of dark respiration are discussed in relation to clonal sensitivity to O₃.     

Disinfection of filtered and unfiltered secondary effluent in two ozone contactors

the objective of this study was to evaluate the effect of filtration of secondary effluent on the mass transfer and disinfection efficiencies of two ozone contactors. The two contactors used in the comparison were a multicolumn bubble diffuser and a stirred tank reactor. The approach chosen was based on a type of statistical experimental design used in a previous contactor comparison. The design made it possible to compare the ozone transfer and coliform reduction efficiencies of the two contactors with respect to applied dose, while at the same time comparing filtered and unfiltered effluent. Results indicated that better mass transfer efficiency and, consequently, better coliform reduction efficiency occurred in the bubble diffuser, and the differences between contactors increased with dose. Mass transfer in both contactors was higher in unfiltered effluent than in filtered effluent. The most significant factors affecting the fecal coliform numbers in the treated secondary effluent were total chemical oxygen demand (COD) and absorbed ozone dose. Regression equations were developed to predict final coliform numbers as a function of COD and absorbed ozone dose.     

Applying mass transfer models for controlling organic compounds in ozonation process

Mass transfer plays a significant role in the ozonation process. The prediction models associated with the volumetric overall mass transfer coefficient (K_La) and initial fractional ozone absorption (FOA₀) during the ozonation process were developed through the use of dimensional analysis. It was found that the volumetric overall mass transfer coefficient is the function of diffusivity, agitation speed, and gas flow rate, and the parameters in the K_La equation are determined. Application of the prediction models for K_La and FOA₀ would yield information to choose the most practically feasible operating parameters. The removability of total organic carbon (TOC) can be estimated based on the mass balance relationship and kinetic expression of TOC oxidation, during continuous laboratory ozonation of humic acid solution. The reaction rate constant averaged 0.0291 L/mg·min. The developed model in combination with the mass transfer and reaction kinetics can be used successfully in forecasting the most efficient agitation speed to control the formation of organic compounds. Also, the critical value of ozone partial pressure to achieve the highest TOC removability can be determined through the use of the above developed model.     

Climate change impacts on a pine stand in Central Siberia

The objective of this paper is to analyse the impacts of climate change on a pine forest stand in Central Siberia (Zotino) to assess benefits and risks for such forests in the future. We use the regional statistical climate model STARS to develop a set of climate change scenarios assuming a temperature increase by mid-century of 1, 2, 3 and 4 K. The process-based forest growth model 4C is applied to a 200-year-old pine forest to analyse impacts on carbon and water balance as well as the risk of fire under these climate change scenarios. The climate scenarios indicate precipitation increases mainly during winter and decreases during summer with increasing temperature trend. They cause rising forest productivity up to about 20 % in spite of increasing respiration losses. At the same time, the water-use efficiency increases slightly from 2.0 g C l^?1 H₂O under current climate to 2.1 g C l^?1 H₂O under 4 K scenario indicating that higher water losses from increasing evapotranspiration do not appear to lead to water limitations for the productivity at this site. The simulated actual evaporation increases by up to 32 %, but the climatic water balance decreases by up to 20 % with increasing temperature trend. In contrast, the risk of fire indicated by the Nesterov index clearly increases. Our analysis confirms increasing productivity of the boreal pine stand but also highlights increasing drought stress and risks from abiotic disturbances which could cancel out productivity gains.     

Risk management of viral infectious diseases in wastewater reclamation and reuse: Review

Inappropriate usage of reclaimed wastewater has caused outbreaks of viral infectious diseases worldwide. International and domestic guidelines for wastewater reuse stipulate that virus infection risks are to be regulated by the multiple-barrier system, in which a wastewater treatment process composed of sequential treatment units is designed based on the pre-determined virus removal efficiency of each unit. The objectives of this review were to calculate representative values of virus removal efficiency in wastewater treatment units based on published datasets, and to identify research topics that should be further addressed for improving implementation of the multiple-barrier system. The removal efficiencies of human noroviruses, rotaviruses and enteroviruses in membrane bioreactor (MBR) and conventional activated sludge (CAS) processes were obtained by a systematic review protocol and a meta-analysis approach. The log₁₀ reduction (LR) of norovirus GII and enterovirus in MBR were 3.35 (95% confidence interval: 2.39, 4.30) and 2.71 (1.52, 3.89), respectively. The LR values of rotavirus, norovirus GI and GII in CAS processes were 0.87 (0.20, 1.53), 1.48 (0.96, 2.00) and 1.35 (0.52, 2.18), respectively. The systematic review process eliminated a substantial number of articles about virus removal in wastewater treatment because of the lack of information required for the meta-analysis. It is recommended that future publications should explicitly describe their treatment of left-censored datasets. Indicators, surrogates and methodologies appropriate for validating virus removal performance during daily operation of wastewater reclamation systems also need to be identified.     

Phosphate removal by activated carbon–silica nanoparticles composite,kaolin, and olive cake

This work aimed to utilize four low-cost materials, namely activated carbon (AC), activated carbon–nanoparticle composite, kaolin, and olive cake, for phosphate removal. Batch mode tests were used to evaluate the performance of the adsorbents. The parameters affecting the adsorption process such as pH, initial concentration, mixing time, dosage, and temperature were studied. The obtained results showed that the removal efficiency of the adsorbents followed the order of: activated carbon–nanosilica > activated carbon > kaolin > olive cake. The addition of silica nanoparticles significantly enhanced the removal efficiency of activated carbon by 18.1% reaching a removal efficiency of 98% at 15wt% nanosilica loading. The adsorption isotherm data fitted well with Langmuir and Redlich–Peterson models with a correlation coefficient of >0.98, which indicates a monolayer homogenous adsorption. The fitness of the kinetic models was ranked as: pseudo-second-order > pseudo-first-order > intraparticle model. The calculated values of ΔH° = 23.4 kJ/mole, ΔS° = 0.11 kJ/mole, and ΔG = ?7.4 to ?11.8 kJ/mole indicated the endothermic and spontaneous nature of adsorption. The positive value of activation energy (17.66 kJ/mole) and the very low value of the sticking probability (2.4 × 10^?4) suggest high indefinite sticking of the phosphate ions to the adsorbent surface. The removal efficiency increased with time, dosage, and temperature, while it decreased with the increase in the initial concentration at an optimum pH of 7. The obtained results buttressed the benefit of using silica nanoparticles to enhance activated carbon capacity for phosphate removal, while kaolin and olive cake provided lower removal.     

Evaluation of Brasilia wastewater sludge as a biomass resource for the production of energy by gasification simulation

This work evaluated the sludge potential of the Wastewater Treatment Plant (ETA) in the city of Brasília to be used as a fuel by gasification. It is known that ETA sludge is a significant environmental liability, since current legislation restricts its final disposal. For this, the chemical characterisation of ETA sludge was performed by immediate and elemental analysis. No traces of heavy metals were observed, and the moisture (ω) and ash contents were 31.17 and 51.77%, respectively, different from those already reported in the literature because the composition depends on the water treatment technology employed. The gasification process was numerically simulated; once dry, it constitutes a residue with an energy content (HHV) of 22.4498 MJ kg^?1, comparable with other types of biomass currently used for large-scale energy generation by thermochemical processes (e.g. agricultural residues, wood and sugar cane bagasse). For the numerical simulation with an equivalence ratio (Φ) near 3, higher concentrations of CO and H₂ can only be achieved with ω lower than 15%. The results showed that gasification can be an attractive option for the disposal and use of a renewable waste resource, such as ETA sludge, in an environmentally safe way, and it is allowed by local legislation.     

Current status of urban wastewater treatment plants in China

The study reported and analyzed the current state of wastewater treatment plants (WWTPs) in urban China from the perspective of treatment technologies, pollutant removals, operating load and effluent discharge standards. By the end of 2013, 3508 WWTPs have been built in 31 provinces and cities in China with a total treatment capacity of 1.48 × 10⁸ m³/d. The uneven population distribution between China's east and west regions has resulted in notably different economic development outcomes. The technologies mostly used in WWTPs are AAO and oxidation ditch, which account for over 50% of the existing WWTPs. According to statistics, the efficiencies of COD and NH₃–N removal are good in 656 WWTPs in 70 cities. The overall average COD removal is over 88% with few regional differences. The average removal efficiency of NH₃–N is up to 80%. Large differences exist between the operating loads applied in different WWTPs. The average operating loading rate is approximately 83%, and 52% of WWTPs operate at loadings of < 80%, treating up to 40% of the wastewater generated. The implementation of discharge standards has been low. Approximately 28% of WWTPs that achieved the Grade I-A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918–2002) were constructed after 2010. The sludge treatment and recycling rates are only 25%, and approximately 15% of wastewater is inefficiently treated. Approximately 60% of WWTPs have capacities of 1 × 10⁴ m³/d–5 × 10⁴ m³/d. Relatively high energy consumption is required for small-scale processing, and the utilization rate of recycled wastewater is low. The challenges of WWTPs are discussed with the aim of developing rational criteria and appropriate technologies for water recycling. Suggestions regarding potential technical and administrative measures are provided.     

Ultrasonically enhanced anaerobic digestion of waste activated sludge

Anaerobic digestion is increasingly applied to stabilise sludge and to reduce operating costs of the wastewater treatment plant by generating biogas, considered as a sustainable energy source. The process suffers from many drawbacks such as slow and incomplete degradation rates, the result of the slow and rate‐limiting sludge hydrolysis step, due to the low biodegradability of the cell walls and the presence of extra‐cellular biopolymers.

Methods to enhance the biogas formation should hence make the substrate more accessible to the anaerobic micro‐organisms. Research on increasing the biogas production is extensive, with low‐frequency ultrasound treatment emerging as the technical and economic most appropriate technology. Although ultrasound is now widely applied in practice, underlying phenomena and optimum operating conditions are still open to debate. Laboratory ultrasound treatment was coupled with digestion experiments (at 37°C) using 12 parallel digesters, two of them being used as control digesters with untreated sludge.

The present paper demonstrates that ultrasound treatment can – within specific ranges of energy‐input – achieve (i) an increased disintegration of the sludge, as witnessed by an increasing soluble COD‐fraction accompanied by an increasing presence of BOD; (ii) an increased release of volatile fatty acids as a result of the oxidising radicals being formed through cavitation; and (iii) a slightly reduced dewaterability of the residual sludge, needing an increased dosage of poly‐electrolyte to obtain a high degree of cake dryness.

As pre‐treatment to digestion, ultrasound enhances the biogas production by more than 40% at low specific energy‐inputs (SE), and approximately 15% at higher SE‐values.     

Fuel efficiency enhancement of modified diesel engine operated in dual fuel mode using renewable and sustainable fuels

ABSTRACT

Renewable and sustainable fuels for diesel engine applications provide energy protection, overseas exchange saving and address atmospheric and socio-economic concerns. This study presents the investigational work carried out on a single cylinder, four-stroke, direct injection diesel engine operated in dual fuel (DF) mode using renewable and sustainable fuels. In the first phase, a Y-shaped mixing chamber or venture was developed with varied angle facility for gas entry at 30°, 45° and 60°, respectively, to enable homogeneous air and gas mixing. Further effect of different gas and air mixture entry on the DF engine performance was studied. In the next phase of the work, hydrogen flow rate influence on the combustion and emission characteristics of a compression ignition (CI) engine operated in DF mode using diesel, neem oil methyl ester (NeOME) and producer gas has been investigated. During experimentation, hydrogen was mixed in different proportions varied from 3 to 12 l/min (lpm) in step of 3 lpm along with air-producer gas and the mixtures were directly inducted into engine cylinder during suction stroke. Experimental investigation showed that 45° Y-shaped mixing chamber resulted in improved performance with acceptable emission levels. Further, it is observed that investigation showed that at maximum operating conditions and hydrogen flow rate of 9 lpm, Diesel–producer gas and NeOME–producer gas combination showed increased thermal efficiency by 13.2% and 3.8%, respectively, compared to the DF operation without hydrogen addition. Further, it is noticed that hydrogen-enriched producer gas lowers the power derating by 5–10% and increases nitric oxide (NO_x) emissions. However, increased hydrogen addition beyond the 12 lpm leads to sever knocking.

Abbreviations: NeOME: Neem oil methyl ester; BTE: brake thermal efficiency; CI: compression ignition; ITE: indicated thermal efficiency; PG: producer gas; CA: crank angle; K: Kelvin; BP: brake power; IP: indicated power; H₂: hydrogen; HC: unburnt hydrocarbon; CO: carbon dioxide; CO₂: carbon dioxide; NO_x: nitric oxide; HRR: heat release rate; %: percentage; PPM: parts per million; CMFIS: conventional mechanical fuel injection system.     

Fate and effect of 2,4-dichlorophenol on biological treatment processes

The fate and effect of continuous feeding of increasing doses of 2,4-dichlorophenol (DCP) were investigated. At the beginning of each run, a drop in the efficiency of the system was recorded, after which a steady state was obtained. Continuous feeding of DCP up to a concentration of 50 mg L^?1 reduced BOD₅ and COD removal rates by 27% and 29%, respectively. Application of shock doses of DCP showed that adaptation increases the capacity of biological systems for removing toxic chemicals.     

Performance analysis of solar water heating system in Centre for DNA Fingerprinting and Diagnostics (CDFD), Southern region of India

In the present study, a natural circulation thermosyphon flat plate solar water heater has been tested at the CDFD, Hyderabad (17.37°N, 78.43°E) Andhra Pradesh, India. Experimental data were noted on a sunny day. Dynamic response of the system to variations in solar insulation was studied and analyzed. T _inlet °C and T _outlet °C temperatures were recorded. The performance of the system can be improved by using aluminum tape inserts into the collector fins. The objective of the present study is to evaluate the performance of flat plate collector with and without inserts (aluminum strip of 1 mm thick, 3 mm width and 203 mm length). It is expected that with the same collector with the same flow rate, higher efficiency can be obtained by inserting the tapes inside the collector copper fins (9 mm). Thus, the cost of the system can be further bringing down by enhancing the collector efficiency.     

Assessment of hydrothermally modified fly ash for the treatment of methylene blue dye in the textile industry wastewater

Dyes and pigments are one of the major water pollutants and if not discharged properly cause ecological disturbance. Considering this, the current study investigates the application of thermal power plant by-product, i.e., fly ash for the elimination of a hazardous methylene blue dye from its synthetic aqueous solution. Experiments were conducted in batch mode to study the effect of pH, temperature, adsorbent dose and contact time. Highest dye removal (94.3%) was achieved at pH 10 using adsorbent dose of 10 g/L in 90 min of contact time at 40 °C. However, for cost-effective operation at neutral pH and room temperature (30 °C), it yields 89.3% dye removal having similar dose and contact time. Equilibrium isotherms for adsorption were analyzed by Langmuir and Freundlich, Temkin and Dubinin–Radushkevich isotherm equations. The results revealed that the best fit model of adsorption closely followed Langmuir adsorption. Based on adsorption isotherm models, thermodynamics parameters ΔG, ΔH and ΔS were calculated. The negative value of ΔG and ΔH revealed that adsorption process was exothermic, spontaneous and physical. The present work suggests that through simple process hydrothermally modified fly ash has the potential to be used as cost-effective and efficient adsorbent for the treatment of wastewater from textile industries.     

Photodegradation characteristics of PPCPs in water with UV treatment

The degradation characteristics of PPCPs commonly found in surface water under UV treatment were examined for 30 kinds of PPCPs using a UV/Lamp1 that emits light at a wavelength of 254 nm and a UV/Lamp2 that emits light at 254 nm and 185 nm in pure water. When a UV dose of some 230 mJ/cm² was introduced to the 30 PPCPs, photodegradation rates of about > 3% (theophylline) to 100% (diclofenac) and about > 15% (clarithromycin) to 100% (diclofenac) were observed for UV/Lamp1 and UV/Lamp2, respectively. This study also showed that UV/Lamp2, which photolyzes water molecules and generates OH radicals, is more effective for PPCP removal than UV/lamp1. It was postulated that the degradation rates of sulfamethoxazole, sulfamonomethoxine, sulfadimethoxine and sulfadimidine, all, including sulfamethoxazole, derived from sulfanilamide, under UV/Lamp1 resulted mainly from the bond-breaking reactions occurring between –SO₂– and its side atoms, the C–S bond and the N–H bond. Some PPCPs with amide bonds, such as cyclophosphamide and DEET, were highly resistant to photodegradation by UV/Lamp1. AOPs (Advanced oxidation processes) such as the UV/H₂O₂ or UV/O₃ processes should therefore be considered for their potential to remove these substances effectively.     

区域经济重心及 COD、SO_2、TSP排放重心演变路径分析——以江苏省为例

运用重心模型,采用1996~2006年江苏省经济和环境数据,计算出各年份GDP、工业产值、COD、SO ₂和TSP排放重心坐标,揭示江苏省经济重心和环境污染排放重心变化轨迹及演变规律,以期为江苏省环境宏观战略决策及生态省建设提供理论参考。研究表明,经济重心总体上向东南方向偏移,GDP重心偏移距离为14.81 km,工业产值重心偏移距离为12.84 km;经济重心在南北方向上的偏移程度大于东西方向的偏移程度。环境污染排放重心也向东南方向偏移,COD和TSP排放重心轨迹呈现较大变化,SO2排放重心轨迹变动较小;COD排放重心偏移距离为79.26 km,SO₂排放重心偏移距离为15.73 km,TSP排放重心偏移距离为42.24 km;各污染排放重心轨迹在不同时段表现出不同特点。COD、SO₂和TSP排放重心相对于经济重心偏向于西北方向,且COD排放重心近年来明显趋向于工业产值重心;COD排放重心和TSP排放重心与经济重心存在着强正相关.     

Treatment of olive mill effluents Part II. Complete removal of solids by direct flocculation with poly-electrolytes

The pre-treatment of three different olive oil processing effluents by means of direct flocculation (i.e. without prior coagulation) was investigated. Four cationic and two anionic poly-electrolytes were tested and most of them were found capable of removing nearly completely total suspended solids (TSS) as well as reducing considerably the concentration of chemical (COD) and biochemical oxygen demand (BOD(5)) without altering solution pH. Flocculant dosage was crucial to achieve effective separation. For three cationic and one anionic poly-electrolytes, the minimum dosage required to initiate separation was about 2.5-3 g/L. The remaining two poly-electrolytes failed to cause separation even at dosages as high as 7 g/L. Lime and ferric chloride were also tested as reference coagulants and found quite effective in terms of TSS removal although the degree of COD reduction was generally lower than that with poly-electrolytes. However, lime treatment would require greater dosages and longer treatment times than that with poly-electrolytes and would also increase considerably solution pH. A preliminary cost analysis showed that lime treatment for complete solids removal was generally less costly than that with poly-electrolytes presumably due to its low market price. Nonetheless, cost-benefits may be defied by several drawbacks associated with the use of lime.