Ash Dosage Research Articles

Viscosity and Strength Properties of Cemented Tailings Backfill with Fly Ash and Its Strength Predicted

It is of great significance to study the effect of solid contents (SC), binder-to-tailings (b/t) ratio, types and dosage of fly ash (FA) on the viscosity (V) and uniaxial compressive strength (UCS) of backfill. It can improve filling efficiency and reduce filling costs to understand the relationship between SC, b/t ratio, FA dosage and viscosity, and UCS of backfill. Consequently, this paper carried out uniaxial compression tests and rheological tests on five different types of backfill specimens. Experimental results indicate that, with the increase of SC, the viscosity and UCS of all backfill samples increases as a power function. With the decrease of b/t ratio, the viscosity and UCS of all backfill samples decreases as an exponential function. The coupling effect of SC and b/t ratio has a great influence on the viscosity and UCS of backfill samples. The relationship between SC, b/t ratio and viscosity, and UCS is a quadratic polynomial function. The order of the viscosity of the backfill slurry is: pure tailings < backfill slurry mixed with Ordinary Portland Cement (OPC) < backfill slurry mixed with FA1 < backfill slurry mixed with FA2. The higher the FA dosage, the greater the viscosity. The order of the UCS of backfill is: backfill with OPC > backfill with FA1 > backfill with FA2. The higher the FA dosage, the smaller the UCS. The UCS of all backfill samples increased with the increase of curing time (CT). The relations between the viscosity and UCS of backfill present the positively linear functions. It is feasible to use viscosity to predict the UCS of backfill, and the error between the UCS predicted value and the test value is mostly controlled within 10%. Ultimately, the findings of the experimental work will provide a scientific reference for the mine to design the strength of the backfill.

A Step towards Sustainable Self-Compacting Concrete by Using Partial Substitution of Wheat Straw Ash and Bentonite Clay Instead of Cement

Self-compacting concrete (SCC) is a special type of concrete that is highly flowable, nonsegregating and spread into place by its own weight, completely filling the formwork even in the presence of dense reinforcement and then encapsulating the rebar without the need for any additional compaction. This research was carried out to evaluate the effects of bentonite clay and wheat straw ash as a partial substitution for cement in SSC. Bentonite clay and wheat straw ash were added in proportion of 0%, 5.0%, 10%, 15%, and 20% of the weight of the cement. Fresh characteristics were evaluated based on its passing ability and flowability using slump flow, slump T50, L-box, and V-funnel tests. After 7 days, 14 days, and 28 days of curing, cylinders of standard size were cast and tested for compressive and split tensile strength. The test results indicate that bentonite clay and wheat straw ash decrease the passing ability and filling ability of SCC. Furthermore, the concrete specimens’ tests indicate that wheat straw ash and bentonite clay additions of up to 10% and 15% of the weight of the cement tend to improve the compressive and split tensile strength of hardened SCC. Response surface methodology (statistical models) is used to optimize the combined dosage of wheat straw ash and bentonite clay and is verified through experimental tests. It can also be suggested that bentonite and wheat straw ash are successfully neutralized in concrete instead of cement.

Strength and Durability Characteristics of Cement and Class F Fly Ash-Treated Black Cotton Soil

This paper analyses improvement of the strength and durability characteristics of black cotton (BC) soil treated with cement and Class F fly ash for pavements. The increase in cement dosage (3–14%) improved the UCS, but the specimens could not resist WD durability cycles. In order to improve, industrial by-product Class F fly ash was used in addition to the cement. Different combinations of cement (10, 12, and 14%) and fly ash (10, 15, 20, 25, and 30%) replacements were evaluated for strength and durability characteristics. The higher dosage of fly ash reduced the plasticity with uniform distribution of cement cluster formations, leading to higher UCS. The soil mixes with (cement + fly ash) stabilizer combinations (10 + 30), (12 + 30), (14 + 25), (14 + 30) were stable against WD test with soil loss < 14%. Mix with (14 + 25) stabilizer showed a maximum retained UCS of 3.6 MPa at 2.9% moisture content (MC) after 12 WD cycles. However, most of the mixes showed high resistance to the FT test. The retained UCS of FT tested specimens was more due to low variations in moisture content. Mix with (14 + 30) stabilizer showed a maximum retained UCS of 2.6 MPa at 23.3% MC after 12 FT cycles. The soil samples with high cement and fly ash contents, with 90 days curing, can exhibit significant strength and more resistance to WD and FT cycles with soil loss < 14%. After drying, severe damage to WD specimens was observed due to the drastic absorption of water during the wetting cycle. Durable samples showed good plunger penetration resistance with an expansion of < 2%. Scanning electron microscopy (SEM) images showed the formations of cemented interclusters. CSH formed resulted in strength improvement, as observed from XRD patterns. The 7 days cured WD specimens did not exhibit any volume expansion on soaking, thawing in water. A maximum volumetric shrinkage of 3.2% on drying and 1.91% on freezing was observed for stabilized soil. Hence, the stronger and durable stabilized soil mixes with high volume stability can be used for pavements.

Experimental study on the freezing resistance and microstructure of alkali-activated slag in the presence of rice husk ash

This study illustrates the significant influences of rice husk ash (RHA) addition on the mechanical properties, freezing resistance and microstructure of alkali-activated slag (AAS) material. The results indicate that the incorporation of rice husk ash enhanced the compressive strength, and reduced the mass loss percentage and compressive strength loss percentage during freeze-thaw cycles, improving the freezing resistance of hardened AAS pastes evidently. The primary reasons for this optimization are the synergistic functions from the potential filling effect of RHA particles and gels enrichment in nature and content of AAS samples. The former refined the capillary pores definitely and the later was responsible for the development of compressive strength. However, the excessive contents (more than 20%) of rice husk ash did make a side effect on the development of freezing resistance and microstructure of AAS samples, which was likely related to the structure of rice husk ash itself. The dosage of rice husk ash used in AAS should be within 20% when considering the achievement of better comprehensive properties.

An Investigation on Fresh and Hardened Properties of Concrete Blended with Rice Husk Ash as Cementitious Ingredient and Coal Bottom Ash as Sand Replacement Material

This research offered that the rice husk ash is served as replacement for cement ingredient such as 5%, 10% and 15% along with 10%, 20%, 30% and 40% of fine aggregates replaced with coal bottom ash in concrete. In this regard, total 180 concrete samples were prepared with mix proportion of 1:2:4 at 0.50 water/cement ratio and theses specimens were cured at 28 days. However, the main theme of this study is to perform the slump test, compressive strength, split tensile strength and water absorption of concrete including different proportions of rice husk ash as replacement for cement and fine aggregates replaced with coal bottom ash separate and combine. The outcome was detected that the workability and water absorption is dropped as the dosages of rice husk ash and coal bottom ash increases in concrete. Moreover, the compressive and split tensile strength is enhanced by 9.10% and 7.73% while the utilizing of 5% RHA along with 30% of fine aggregate replaced with coal bottom ash in concrete at 28 days consistently.

Study on Adsorption of Dye Wastewater by Modified Fly Ash

Used fly ash as raw material, it was modified by acid, alkali and high temperature to produce modified fly ash adsorbent, sulfuric acid modified fly ash adsorbent, sodium hydroxide modified fly ash adsorbent and high temperature modified fly ash adsorbent. In this paper, the effects of adsorbent dosage, adsorbent adsorption time, initial dye concentration, wastewater pH and temperature on dye adsorption were studied. The results showed that: the acid modified fly ash adsorbent had a good treatment effect on the dye; when the dosage of fly ash was 1.00 g, the adsorption time was 90 min, the pH of wastewater was 4, and the temperature was 45 °C, the decolorization rate of 60 mg/L methyl orange dye can reached more than 70%; when the dosage of fly ash was 0.20 g, the adsorption time was 60 min, the pH of wastewater was 3, and the temperature was 35 °C, the decolorization rate of 20 mg/L methyl orange dye can be achieved. The decolorization rate of Congo red can reached more than 80%.

Assessment of the Semi-Adiabatic Temperature Rise of Mass Concrete Containing Bagasse Ash

Previous studies show that pozzolan materials are a wise choice for retarding significant heat in mass concrete placements. This research aims at studying the early age thermal property of concrete containing bagasse ash under different ambient temperatures. Moreover, the compressive strength of concrete specimens with varying ratios of the mix is assessed. Semi-adiabatic temperature rise data of four different concrete mixtures (containing pure Portland cement, 6.5%, 13%, and 20% dosage of bagasse ash by volume) are determined. Concrete specimens of size 30cm*30cm*40cm were cast and insulated using Styrofoam. The temperature measurement is taken at three different locations for every 30 minutes of interval. The influence of ambient temperature on specimens' early age thermal response is studied using a temperature chamber capable of simulating 25.15°C, 35.54°C, and 43.77°C average ambient temperatures. The results indicated that bagasse ash could replace the cement up to an optimum replacement level of 10 percent even if an early age strength drop is observed. The experiment revealed that the bagasse ash in the concrete mixture shift the temperature rise-time profile, reduces the total heat of hydration, and decreases the thermal gradient in the specimens. The peak temperature gauge of all mixes elevated as the ambient temperature increased, but mixtures containing bagasse ash show a slower heat liberation rate relative to the control group. The study proves pozzolan reaction is slow, releasing heat over a long period and not taking place early. It has merit in a massive concrete placement where cooling can lead to cracking following a significant temperature rise.

Assessment of the Mechanical Properties of Bagasse Ash Concrete

Sugarcane bagasse ash is found abundantly in Ethiopia. Researchers in the area focus to sustainably use this pozzolan as a raw material for concrete production. This study aims to investigate the early and late age mechanical properties of Bagasse ash concrete. Concrete mixtures containing pure Portland cement, 6.5%, 13%, and 20% dosage of Bagasse ash by volume were proportioned. The compressive, tensile, flexural strength data at one, two, three, seven, twenty-eight days are determined. The experimental outcomes indicate that the tensile strength of bagasse ash concrete for 6.5% and 13% replacement ratio dropped by 6.98% and 22.5% compared to full cement concrete at three days of testing. As well, there is a reduction of third-day flexural strength by 5.96% and 13.1%. In advance, the 28th-day flexural strength increased by 6.38% and 17.02% for 6.5% and 13% replacement ratio. The compressive strength of bagasse ash concrete with 6.5% and 13% replacement ratios exceed the control group's 28th-day strength by 3.46% and 6.64% sequentially. Possibly, the ettringite formed as the base solution reacts with metallic oxides densifies the interfacial transition zone. Bagasse ash also contains inert unburned carbon particles that will fill the voids of hardened concrete. On the other hand, replacing cement with bagasse ash up to 20% reduces both the early and late age flexural strength and tensile strength development of concrete.

Numerical and experimental investigation of concrete with various dosages of fly ash

<abstract> The nonlinear behavior of reinforced fly ash concrete (RFAC) beams until the ultimate failure is highly a multifaceted phenomenon due to the contention of heterogeneous material properties and the cracking behavior of concrete. This paper represents an exploration of nonlinear finite element analysis of reinforced concrete beams with the inclusion of fly ash under flexural loading. Finite element modelling of RFAC beams is carried out using a distinct reinforcement modelling method. The capability of the model to capture the critical crack regions, loads and deflections for various loadings in RFAC beams has been evaluated. Comparison is made between experimental results and finite element modelling with respect to crack formation and the ultimate capacity for flexural loading and mid-span deflection. The achieved results in the present study indicate acceptable approximation with those in the previous investigations. </abstract>

Sono-assisted adsorption of acid violet 7 and basic violet 10 dyes from aqueous solutions: Evaluation of isotherm and kinetic parameters

In this study, the removal of acid violet 7 (AV7) and basic violet 10 (BV10) synthetic dyes was investigated using fly ash alone, ultrasound (40 kHz) alone, and combined ultrasound/fly ash with various experimental parameters such as fly ash dose, contact time, and initial concentration of dye. The adsorption capacity of the ultrasound/fly ash process increased from 5.10 to 7.43 mg g-1 for AV7, and increased from 5.16 to 7.51 mg g-1 for BV10 compared with using fly ash alone. The sono–assisted adsorption process was successful in improving the dye uptake capacity with cavitation bubbles and acoustic waves, and thus AV7 and BV10 were removed with a shorter contact time and lower fly ash dose. Obtained regeneration and reuse experiment results showed that the fly ash could be reused for four consecutive cycles of the sono–assisted adsorption process, while fly ash could be reused for two consecutive cycles of the adsorption process. The adsorption kinetics for AV7 and BV10 onto fly ash fitted Lagergren’s first–order adsorption kinetic model well. The Langmuir isotherm best described the adsorption with fly ash alone and ultrasound/fly ash process for AV7 and BV10.

MOC Cement-Based Composites with Silica Filler and Wood Chips Ash Admixture

As Portland cement and cement-based materials are the most widespread materials in construction industry, there is a concern to develop and search cement alternative materials with similar or better functional properties and a lower negative environmental impact. Magnesium oxychloride cement (MOC) is considered as low-energy and low-carbon binder possessing some advantageous properties superior to Portland cement. Therefore, lightweight MOC-based composites were designed and tested in the presented study. As filler, silica sand was used in composition of control composite mix. Later, it was partially replaced with wood chips ash coming from bioenergy production from biomass. The chemical composition and morphology of wood chips ash were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analyses. For the hardened composites, bulk density, specific density, and total open porosity were measured. Among mechanical parameters, flexural and mechanical strengths were tested. The thermal performance of composites was studied using a transient hot disk method and the assessed parameters were thermal conductivity and volumetric heat capacity. The use of fly ash led to the great decrease in porosity compared to the control materials with silica sand as only filler. The mechanical strength of all developed materials was high. Both the compressive strength and flexural strength decreased the dosage of wood chips ash in composite mix. However, the decrease in mechanical resistance was lower than the send replacement ratio. It clearly proved assumption of filler function of fly ash, whereas its assumed reactivity with MOC cement components was not proven. The heat transport was partially mitigated by wood chips use, similarly as heat storage. Based on the obtained data, the developed composites were considered as alternative low-carbon materials possessing interesting functional properties for construction practice. Moreover, the reuse of by-product from biomass bioenergy treatment can be considered as an environmentally friendly solution for production of sustainable advanced building materials.

Optimization of copper removal from wastewater by fly ash using central composite design of Response surface methodology

This study aimed to investigate the possibility of utilizing a locally available fly ash as a low-cost adsorbent material for the removal of copper from aqueous solution. Though copper is an essential element, it can be poisonous to human beings at higher concentrations. The removal efficiency of copper is studied under the different initial concentrations of copper (20–50 mg/L), pH (2–6), and fly ash dosage (20–80 g/L). A second-order polynomial model is proposed to study the interactive effects of the parameters. The result of the analysis of variance (ANOVA) confirms the quadratic model is very significant. The optimization of the process variables is carried out by using a full factorial rotatable Central Composite Design (CCD) in Response Surface Methodology (RSM) by Design-Expert Software (Version 6.0.8, State Ease, USA). The maximum removal of copper is achieved at an initial copper concentration of 43 mg/L, pH 6, and fly ash dosage 63 g/L. The value of the determination coefficient (R2) is found to be 0.9945. The value of Prob > F of the developed model is < 0.0001, indicating the applicability of the model. The fly ash has been analyzed by XRD, DTA, FTIR, and SEM/EDS techniques. The results of this study indicate that this fly ash can be used as a low-cost adsorbent to treat acidic wastewater generated from industries like electroplating, fertilizer, copper smelting, acid mine drainage, etc.

A Mineral By-Product from Gasification of Poultry Feathers for Removing Cd from Highly Contaminated Synthetic Wastewater

Ash from poultry feather gasification was investigated as an adsorbent for Cd removal from synthetic wastewater under a range of operational conditions: initial pH (2–8) and salinity (8–38 mS/cm) of wastewater, ash dosage (2.5–50 g/L), Cd concentration (25–800 mg/L) and contact time (5–720 min). The ash was highly alkaline and had low surface area and micropores averaging 1.12 nm in diameter. Chemical/mineralogical analysis revealed a high content of P2O5 (39.9 wt %) and CaO (35.5 wt %), and the presence of calcium phosphate, hydroxyapatite and calcium. It contained only trace amounts of heavy metals, BTEX, PAHs and PCBs, making it a safe mineral by-product. Cd adsorption was described best with Langmuir and pseudo-second order models. At pH 5, an ash dosage of 5 g/L, 40 min contact time and 100 mg Cd/L, 99% of Cd was removed from wastewater. The salinity did not affect Cd sorption. The maximum adsorption capacity of Cd was very high (126.6 mg/g). Surface precipitation was the main mechanism of Cd removal, possibly accompanied by ion exchange between Cd and Ca, coprecipitation of Cd with Ca-mineral components and Cd complexation with phosphate surface sites. Poultry ash effectively removes high concentrations of toxic Cd from wastewater.

Removal of TDS and TSS from Industrial Wastewater using Fly Ash

Fly ash is one of the most abundant waste materials; its major components make it a potential agent for the adsorption of pollutants contaminants in water and wastewaters. In this study, fly ash obtained from burning of mazut was dried and sieved into different fractions (600, 300, 150, 75µm). A pilot plant with an industrial discharge flow of 200L/hr was designed for reducing total Dissolved Solids (TDS), total suspended solids (TSS), conductivity and pH from industrial wastewater. The concentrations of (TDS), (TSS), conductivity and pH in industrial discharge flow had an average range of 80000, 750, 120000 mg/L and 13 respectively. The optimization of the treatment process using 5, 8, 12, 15 g/L fly ash dosage had succeeded in improving the removal efficiency of (TDS), (TSS), conductivity and pH to 90%, 92.3%, 90% and 93.5% respectively.

Effect of High Concentrations of Wood Ash on Soil Properties and Development of Young Norway Spruce (Picea abies (L.) Karst) and Scots Pine (Pinus sylvestris L.)

Wood ash recycling can be a reasonable method for energy producers to decrease waste problems. Using wood ash as a fertilizer or liming material could improve soil macro and micronutrient content in peat soils. Therefore, the effect of wood ash on Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.) juvenile growth and nutrient content in the soil after spreading wood ash in medium to high doses before and after planting seedlings was investigated in peat forests in the Eastern part of Latvia. The aim of the study was to evaluate the effect of high doses of wood ash on soil properties and the growth of planted Norway spruce and Scots pine seedlings up to 10 years after experiment establishment. Wood ash was applied a year before planting seedlings in doses of 5 and 10 t ha−1 and right after planting in concentrations of 5, 10, 15, and 20 t ha−1. Changes in macronutrient content (i.e., phosphorus [P], and potassium [K]) and tree height and diameter at breast height were measured at one and 10 years after establishing the experiment. Fertilization one year prior to planting the seedlings exhibited a positive response on tree height and diameter growth compared to fertilization after the seedlings were planted. Soil samples from fertilized plots one year after establishment contained more P and K in the soil than the control plots. Wood ash application of the highest doses did not reach the overdose limit, as the tree growth (height and diameter at breast height) results of fertilized plots were similar to those of the control fields; therefore, no significant negative effect on tree growth was discovered.

Long-term effects on soil-water chemistry of wood ash and nitrogen application in a conifer forest

Wood-ash application to forestland has been proposed as a means to compensate for increased nutrient removal when harvesting logging residue in addition to stems. A study-plot experiment was established on a mineral soil site in Sweden to investigate how this measure affects soil-water chemistry. In 1995, 10 treatments were applied. Here, we present results from 9 to 17 years after application for eight of the treatments: control; 3 × 103, 6 × 103, and 9 × 103 kg·ha−1 of self-hardened and crushed wood ash (WA); 150 kg N·ha−1 supplied as ammonium nitrate; 3 × 103 kg WA and 150 kg N·ha−1 applied simultaneously; 3 × 103 kg WA with 150 kg N·ha−1 applied 1 month before the ash; and 3 × 103 kg·ha−1 of pelleted ash. Soil-water samples were collected from a depth of 50 cm. Treatment effects (p &lt; 0.05) were detected in the electrical conductivity, pH, and concentrations of K+, Mg2+, Ca2+, Al, SO42−-S, and B. Elevation of K+ and SO42−-S concentrations tended to cease toward the end of the study period. Effects were generally more pronounced with increasing ash dosage. No difference was detected between the 150 kg N·ha−1 treatment and the control. Despite the high solubility of the ash, its effects on soil-water chemistry could still be detected 9–17 years after application.

Impact of material properties on characteristics of engineered cementitious composite

Abstract Engineered Cementitious Composite (ECC) is one of the high crack-resistive composites due to elimination of the coarse aggregates in the composition. The size of the coarse aggregates is responsible for crack propagation in the structural components. By avoiding this, the characteristics of the ECC mainly depends on the silica sand. This type of fine aggregate is also responsible for self-consolidation characteristics but due to less availability and more cost increases the necessity of alternatives. Indian Zone II fine aggregates are used as alternatives of silica sand in this experimental work. For this, four ECC mixtures were considered. F_1.0_SS and F_1.2_SS are the silica sand based mixtures at fly ash to cement dosage (f/c) of 1.0 and 1.2 repectively. F_1.0_RS and F_1.2_RS are the Indian zone II sand-based mixtures at f/c of 1.0, and 1.2 respectively. The flowability and self-consolidation characteristics of these mixtures were analyzed and specimens were cast to study the hardening and durability characteristics at 28 days curing period. All considered ECC mixtures were showed good self-consolidation characteristics. The mechanical characteristics of ECC are slightly changed from F_1.0_SS to F_1.0_RS and F_1.2_SS to F_1.2_RS.The ECC mixtures with Indian zone II sand showed the same mechanical characteristics compared to silica sand but higher fly ash dosage responsible for the decrease in strength. The durability characteristics also slightly impacted by Indian zone II sand. These results showed Indian zone II fine aggregates can use as an alternative for silica sand.

Growth Response of Red Spinach (Amaranthus Gangeticus) by Giving Cow Manure and Rice Husk Ash.

The increase in market demand red spinach (Amaranthus Gangeticus) makes the prospects very promising less than optimal for the growth of red spinach (Amaranthus Gangeticus) because soil fertility is low so that the provision of organic material can improve soil fertility through the improvement of the physical, chemical, and biological soil so that it can support the growth of red spinach. This study aims to determine the dose of manure, the dosage of rice husk ash as well as the interaction of dosage that is optimal for the growth and yield of red spinach.this research was conducted experimental farm of the faculty of science and technology with a height of 28 meters above sea level Labuhanbatu district in March to October 2020. Research design using group factorial consisting of two factors. The first factor, namely the granting of cow manure (L) with three levels, namely : L0 = 0 ton/ha (control) L1 = 2 ton/ha, equivalent to 200 g/m2 (the recommended dose), L2 = 4 ton/ha, equivalent to 400 g/m2, L3 = 6 ton/ha, equivalent to 600 g/m2. The second factor, rice husk ash (A) consists of 4 levels, namely : A0 = 0 ton/ha (control), A1 = 1 ton/ha equivalent to 50 g/m2 (the recommended dose), A2 = 1.5 tons/ha, equivalent to 75 g/m2.The Parameters measured were plant height (cm), number of leaves (strands), Weight per Plant Sample (g). The results showed that the administration of cow manure 4 ton/ha, equivalent to 400 g/m2 can increase plant height, leaf number, and weight per Plant of amaranth red. The provision of 1.5 tons/ha, equivalent to 75 g/m2 can increase plant height, the number of leaves plant red spinach (Amaranthus Gangeticus).Keywords: Rice Husk Ash, Red Spinach, Cow Manure, Plant Growth

Effect of fly ash addition on slurry dewatering by electro-osmosis combined with mechanical pressure

In this study, fly ash was used as an additive to increase the dewatering efficiency of an excavated soil slurry treated by electro-osmosis combined with mechanical pressure and thus effectively obtain a low-moisture treated slurry with wider applicability; the properties of the treated slurry were also studied. The results showed that, at a fly ash dosage of 5%, the drainage volume was 350 mL, which presented significantly better dewaterability properties than the unconditioned slurry, the water content of the anode and cathode layer after treated was 20.5% and 19.1%, the compressibility coefficient was 0.170 MPa−1 and 0.152 MPa−1, and the shear strength was 81.2 kPa and 85.1 kPa, respectively. And we also studied the physical properties of the treated slurry at different locations, the physical properties were also affected by the fly ash dosage. It was concluded that fly ash used in adequate concentrations can reduce the slurry water content, and fly ash also can improve the mechanical properties of excavated soil slurry after the mechanical dewatering combined with electro-osmosis.

Growth of palm oil seedlings at various doses of boiler ash and tofu wastewater

The objective of the study is to get the best dose of boiler ash and tofu wastewater to increase the growth of palm oil seedlings in the nurseries. The study used a completely randomized design in factorial with three replications. The first factor is the dose of boiler ash consisting of four levels, namely 0 g, 300 g, 350 g, 400 g, and 450 g per polybag. The second factor is the concentration of tofu wastewater, which consists of four levels, namely 0%, 60%, 80%, 100% per polybag. The results showed that the interaction between boiler ash and tofu wastewater had a significant effect on the growth of palm oil seedlings in the nurseries. Interaction between boiler ash doses 350-450 g per polybag with tofu wastewater concentration 80-100% per polybag can increase seedling height, shoot diameter, root volume, and dry weight of palm oil seedlings.