Solids Removal Research Articles

Influence of inoculum-to-substrate ratio on biogas enhancement during biochar-assisted co-digestion of food waste and sludge

ABSTRACT High accumulation of volatile fatty acids (VFAs) is one of the major concerns during mesophilic anaerobic co-digestion of food waste (FW) and sewage sludge (SS). Therefore, improving the stability of the anaerobic digestion process could surpass quick acidification while accelerating methanogenesis. In this study, the suitability of biochar-assisted co-digestion was evaluated at different inoculum and substrate ratios (I/S ratios: 0.1, 0.3, 0.6, and 0.9). The maximum methane yield of 256.85 mL/gVSadd was observed at an I/S ratio of 0.6. The results indicated fast volatile solid removal (∼ 47.17% to 73%) and a critical role of biochar addition in alleviating the underlying inhibitions. Substantial changes in the microbial community composition including Methanosata, Methanobrevibacter, and Methanosarcina were also observed which predominated and stabilised the methanogenesis process at higher I/S ratios. These results emphasised that the anaerobic co-digestion of FW/sludge is a promising approach, wherein the biochar amendment at different I/S ratios should be well maintained to avoid inhibitions from excess microbial VFA acidification of organic waste feedstocks.

Effect of Different Operational Conditions on the Treatment Performance of Milk Processing Wastewater (MPW) Using a Single Stage Flexible Fibre Biofilm Reactor (SS-FFBR)

The performance of a biofilm system, single-stage flexible fibre biofilm reactor (SS-FFBR) treating milk processing wastewater (MPW) is evaluated under various process and operational conditions. The system behavior is analyzed with different biological and physical parameters. Results show that the high COD removal efficiency of 95% is obtained at a low CODin concentration of 809 mg/L. However, the COD removal is slightly decreased to 91.7% once the CODin concentration incremented to nearly 4000 mg/L. The effect of organic loading rate (OLR) on the SS-FFBR performance is examined as total suspended solids removal efficiency, dissolved oxygen, and turbidity. The SS-FFBR showed considerable performance, so that 89.9% and 89.7% removal efficiencies in terms of COD and TSS removals, respectively, obtained at the highest OLR of 11.7 kg COD/m3d. TSS removal efficiency of 96.7% is obtained at a low OLR of 1.145 kg COD/m3d. A linear relationship between the OLR and COD removal rate was revealed. The COD removal rate was incremented from 1.08 to 10.68 kg COD/m3d as the OLR increased from 1.145 to 11.7 kg COD/m3d. Finally, the operating system is a promising technique recommended to treat various industrial wastewaters with high OLR.

Performance of sand filter with disc and screen filters in irrigation with rainbow trout fish effluent

AbstractDrip irrigation is the most suitable system for reusing effluents in agriculture, but emitter clogging is still its major drawback. Adequate filtration is needed to prevent emitter clogging, but little information is available about the performance of different filter types when using fish farm effluent. The purpose of this study was to evaluate the performance of three filtration treatments for rainbow trout effluent in drip irrigation systems: (1) sand filter (T1), (2) sand filter followed by a disc filter (T2) and (3) sand filter followed by a screen filter (T3). The treatments were tested with a constant discharge of 14.4 m3 h−1 at two working pressures of 300 and 150 kPa until reaching the backwashing threshold. For each filter, the following were computed: filtered volume per cross‐section until reaching the backwashing threshold (VB), filtered volume per cross‐section unit and head loss (V10), suspended solids removal efficiency (EF) and filter mass retention (q). T2 at 300 kPa had a significantly (p < 0.01) higher VB, whereas T1 and T3 only showed a VB of 53% and 45% at 300 kPa and 48% and 47% at 150 kPa, respectively, higher than that obtained by T2. The results suggest that using a combination of sand and disc filters at an operation pressure of 300 kPa is the best option when using rainbow trout effluent.

Coagulation-Flocculation Process of Nutrient-Rich Suspended Solids from Aquaculture Effluent Using Bioflocculant

Due to the growth and development of the aquaculture industry, appropriate wastewater treatment is needed to reduce uncontrolled pollution and environmental impacts. Therefore, this research uses green technology method, which is the coagulation-flocculation process to treat aquaculture wastewater. Natural flocculants have been the focus of research of many research due to the negative impact from using chemical flocculant. In this study, the potentiality of local plants of moringa leaves and seed (Moringa oleifera), banana pith (Musa), neem leave (Azadirachta indica) and Pandan leave (Pandanus amaryllifolius) as bioflocculant were studied. This study also focuses on nutrient recovery. The potential of sludge obtained through the coagulation-flocculation process as fertilizer was investigated in comparison with commercial fertilizer. Through this study, it is shown that Moringa oleifera seed recorded the highest rate of suspended solid removal from synthetic kaolin water at 36.7% and highest turbidity removal rate at 34.8%. Previous studies have shown that aquaculture sludge contains 1.27 % of nitrate, 0.32 % of phosphorus and 0.65 % of potassium. The characteristics of sludge produced through the process of coagulation-flocculation resembles organic fertilizer. This shows that treated aquaculture sludge has potential to be used as an organic fertilizer. With this, it can promote the use of sustainable green technology for effective aquaculture wastewater treatment.

The role of heat/powdered activated carbon/persulfate in membrane fouling control in a coupled aerobic granular sludge–membrane system for municipal wastewater reclamation

This study proposed and applied an innovative heat/powdered activated carbon (PAC)/persulfate (PS) pre-treatment system for the first time in an aerobic granular sludge–membrane system (AGSMS). We examined the effects of the heat/PAC/PS system on membrane fouling mitigation and contaminant removal and qualitatively evaluated the contribution of adsorption and oxidation to membrane fouling control. Compared to other pre-treatment systems, the heat/PAC/PS system could enhance the removal of pollutants, reduce fouling resistance, and delay the decline of permeation flux, resulting in low foulant content on the membrane surface and formation of a loose and porous cake layer. According to radical scavenging experiments, the excellent heat/PAC/PS system pre-treatment performance was attributed to the PAC adsorption capacity and non-radical oxidation pathway. Thermal synergy played a significant role in promoting adsorption and oxidation abilities. The extended Derjaguin–Landau–Verwey–Overbeek theory indicated that the high-energy barrier in the heat/PAC/PS system was an important factor in inhibiting the adhesion of foulants to the membrane surface. Furthermore, the correlation analysis suggested that membrane fouling control should focus on the removal of chemical oxygen demand and suspended solids. This study provides a new approach for membrane fouling mitigation through AGSMS in municipal wastewater treatment.

Syntrophic Butyrate-Oxidizing Consortium Mitigates Acetate Inhibition through a Shift from Acetoclastic to Hydrogenotrophic Methanogenesis and Alleviates VFA Stress in Thermophilic Anaerobic Digestion

In anaerobic digestion (AD), butyrate is degraded by syntrophic consortium, but can accumulate in highly loaded AD systems. The effect of butyrate on the AD process attracts much less attention than propionate or acetate. In this work, an enrichment culture of the thermophilic butyrate-oxidizing syntrophic consortium was obtained by gradually increasing the initial butyrate concentration from 20 to 170 mM. Surprisingly, even the highest butyrate concentration did not significantly inhibit the methanogenic community, and the stage of acetate degradation was the limiting overall rate of the process. At 170 mM butyrate, the bacterial community changed towards the dominance of syntrophic acetate-oxidizing (SAO) bacteria related to Syntrophaceticus (42.9%), Syntrophomonas (26.2%) and Firmicutes (26.2%), while the archaeal community experienced a sharp decrease in the abundance of Methanosarcina thermophila (from 86.0 to 25.0%) and increase in Methanothermobacter thermautotrophicus (from 3.2 to 53.1%) and Methanomassiliicoccus (from 3.2 to 21.9%). Thus, the shift from acetoclastic methanogenesis to SAO coupled to hydrogenotrophic methanogenesis occurred as an adaptive strategy to overcome high acetate (~200 mM) build-up. Bioaugmentation with the obtained enrichment culture was effective in mitigating the butyrate-dominated VFA build-up during the AD of readily biodegradable waste, increasing the methane production rate, methane yield and volatile solids removal by more than 3.5, 6.2 and 2.9 times, respectively. Our study revealed that the thermophilic butyrate-oxidizing consortia as bioaugmented culture could be the potential strategy to alleviate the high organic load and VFA stress of AD.

Restrictions in water treatment by conventional processes (coagulation, flocculation, and sand-filtration) following scenarios of dam failure

Dam failure events can result in a high suspended solids concentration in surface waters. To understand the impact of high suspended solids concentration on the treatment process of water treatment plants, this study investigated coagulation-flocculation stages using different coagulants (ferric chloride and a polymeric coagulant – CAT-FLOC 8799 Plus) and solids concentrations (2000–46,000 mg/L), and how they impacted on the mean diameter (d50), density (ρs), and settling velocity (vs) of the agglomerates formed. After the sedimentation process, the turbidity values varied between 201–26 NTU when FeCl3 was used as a coagulant, and 36–11 NTU when using the organic coagulant. The study reinforces the effect of particle diameter on sedimentation velocity, which is lower for cases involving smaller average diameters. Even so, solids removal was high regardless of the initial conditions and characteristics of the agglomerated particles, starting early in flocculators with removals >80 %. The results point to the need for frequent maintenance of these units to remove the sludge settled, which could compromise the operation of water treatment plants. In this sense, two alternatives were proposed as pre- and post-treatment. Under high total solids concentration (>20,000 mg/L), pre-treatment with thickeners becomes mandatory, and ultrafiltration comes as an additional barrier that will prevent high turbidity values in drinking water. In this study, the use of ultrafiltration membranes in partial or total replacement of sand filters showed stable performance (permeate flow: 130–136 L/m2h) with no tendency to fouling and guaranteeing a residual turbidity value <0.3 NTU. Future studies should prove the technical and operational feasibility of the strategies proposed, which until then showed promising results to guarantee the operation of water treatment plants in adverse scenarios.

Municipal wastewater treatment with corrugated PVC carrier anaerobic baffled reactor.

The anaerobic baffled reactor (ABR) is a promising solution for decentralized wastewater treatment due to its low operation cost as compared to the activated sludge process, but it requires comparatively higher hydraulic retention time (HRT). This ultimately increases land requirement, capital and construction cost of treatment plant. This study investigates performance of ABR using polyvinyl chloride (PVC) corrugated pipe as carrier media to improve biomass retention capacity and treatment performance of reactor with the aim to reduce HRT. Comparative performance of two ABRs with and without carrier media was analyzed under mesophilic conditions (35 ± 1 °C) for organics and total suspended solids (TSS) removal at HRTs of 24, 18, 12, 8, 6 and 4 h. Results showed that at HRTs of 24-08 h, the organics removal performance of the carrier anaerobic baffled reactor (CABR) was better than ABR and was in the range of 77-81% for CABR as compared to 64-70% for ABR. However, on further decrease in HRT to 6 h, CABR sustained the treatment with organics removal of 80%, while ABR performance reduced to 58%, creating a performance difference of 38%. Average total suspended solids (TSS) removal was in the range of 76-83% at all HRTs for both reactors. Therefore, this study identified CABR with PVC carrier media as an effective low-HRT reactor for organics and SS removal with less land area requirement.

Effects of Ozone Dose and Contact Time on Ozonation Process Performance for Treatment of High Rate Activated Sludge Process Effluent

ABSTRACT In recent years, there has been an increase in the interest on organic compounds originating from anthropogenic activities. The presence of these micropollutants in waterbodies can be detrimental for the aquatic organisms even at their trace concentrations. Removal of micropollutants from wastewater by conventional treatment methods is quite limited, thereby existing wastewater treatment plants are not capable of removing these micropollutants. This study investigated the removal of 27 micropollutants and conventional pollution parameters by ozonation of the effluent from a pilot-scale high-rate activated sludge system treating municipal wastewater. Different ozone dosages and contact times were tested during the study. Results revealed that 7 out of 27 micropollutants were detected in the effluent. Over 45% chemical oxygen demand (COD) removal and over 65% total suspended solids (TSS) removal were achieved by the ozonation process. Among the various ozone dosage and contact time combinations investigated in the study; 6 mg/L ozone dosage-20 min contact time, and 9 mg/L ozone dosage-10 min contact time alternatives resulted with the best treatment performance in terms of the removal of micropollutants, COD, TSS, and turbidity. A feasibility analysis was conducted to evaluate the best operational conditions from a techno-economic perspective and the results revealed that the unit cost for ozonation process ranged between 0.033 $/m3 and 0.043 $/m3. Additionally, considering the feasibility, 6 mg/L ozone dose – 20 min contact time combination was found as the optimum alternative. Based on the promising results obtained in this study, ozonation can be offered as a polishing step for the effluents of high-rate activated sludge systems for the improving of the effluent quality.

Effects of particle wettability and water moisture on separation efficiency and drop size distribution of particle-laden droplets in oil

Solid/oil separation is widely used in various industrial fields. Conventional methods can effectively separate solids with large particle sizes from oil media; however, removing fine solids using these methods remains challenging. Researchers have attempted to remove fine particles by applying wettability modification, interface capture, and sedimentation, but these methods have several disadvantages and exhibit low efficiency. The relationship between wettability, solid removal rate, and drop size distribution variation of particle-laden droplets remains unclear. Herein, we propose the application of a centrifugal field to enhance the water-based “forth flotation” and investigate its separation characteristics experimentally. Separation experiments under gravity and centrifugal conditions were performed, and the sedimentation of particle-laden droplets dispersed in oil was conducted. The effects of wettability and initial water moisture on separation efficiency were explored, and the solid/oil separation mechanism was analyzed. The variation in the drop size distribution under different conditions was evaluated, and a mathematical relation for predicting the initial average drop size of particle-laden droplets was fitted. In addition, the fitted mathematical expression can be utilized to predict the initial average drop size of particle-laden droplets.

CO2 Addition and Semicontinuous Feed Regime in Shaded HRAP—Pathogen Removal Performance

The influence of CO2 addition and feeding regime (continuous versus semicontinuous) on the removal of Pseudomonas aeruginosa, Clostridium perfringens, Staphylococcus, Enterococcus faecalis, and Escherichia coli (E. coli) from three shaded high-rate algal ponds (HRAPs) treating raw sewage (RS) was studied. The three HRAPs were operated at an analogous hydraulic retention time (HRT) for 5 days and with shading of 50%. The CO2 addition and feeding regime had no statistically significant influence on the removal of Pseudomonas aeruginosa, Clostridium perfringens, Staphylococcus sp., and Enterococcus faecalis, with 2.39–3.01, 2.07–2.31, 3.02–3.38, and 3.14–3.45 log units, respectively. However, the removal of E. coli decreased significantly with the feeding regime of 0.1 h d−1 and 2.23–3.29 log units. The productivity and the total suspended solids (TSS) removal efficiency were significantly improved with the semicontinuous feeding regime and CO2 addition. The highest productivity was obtained in the semicontinuous feeding regime, 5.93 g m2 d−1, while the TSS removal efficiency was similar between the semicontinuous feeding regime and CO2 addition (31–36%). The control of light intensity led to greater variability in the algal community, and was present in the three reactors, in different proportions, in the form of the microalgae Scenedesmus acutus, Scenedesmus obliquus, and Chlorella sp.

EVALUATION OF SETTLEABLE SOLIDS REMOVAL METHODS IN RECIRCULATING AQUACULTURE SYSTEM

EVALUATION OF SETTLEABLE SOLIDS REMOVAL METHODS IN RECIRCULATING AQUACULTURE SYSTEM

Comparative Study of Methane Production in a One-Stage vs. Two-Stage Anaerobic Digestion Process from Raw Tomato Plant Waste

An anaerobic digestion process performed in two stages has the advantages of the production of hydrogen in addition to methane, and of further degradation of the substrate over the conventional process. The effectiveness of the implementation of this system for the treatment of lignocellulosic waste has been demonstrated. In 2020, more than 180 million tons of organic waste were generated worldwide from tomato crop production, posing a serious environmental risk. In the present investigation, methane production was compared in a two-stage system versus one-stage system from non-pretreated tomato plant residues. For this, different temperature (37 and 55 °C) and initial pH (5.5 and 6.5) conditions were evaluated during hydrogenesis and a constant temperature (37 °C, without pH adjustment) during methanogenesis. At the same time, a one-stage treatment (37 °C, without pH adjustment) was run for comparison purposes. The two-stage treatment in which the highest production of hydrogen, 12.4 mL/g VS, and methane, 252.3 mL/g VS, was observed occurred under the conditions of pH 6.5 and at 37 °C. However, this energy production was statistically similar (p &lt; 0.5) to the one-stage treatment (365.4 mL CH4/g VS). Furthermore, there were also no significant differences in the removal of volatile solids between the different treatments.

The Material Flow and Stability Performance of the Anaerobic Digestion of Pig Manure after (Hyper)-Thermophilic Hydrolysis Is Introduced: A Comparison with a Single-Stage Process

Slow hydrolysis persistently affects the anaerobic digestion of animal manure. Thermophilic and hyper-thermophilic treatments introduced into a two-stage anaerobic process treating pig manure were investigated, with a single-stage mesophilic process as a control. The results from the 100-day experiment showed the thermophilic-mesophilic system had the highest removal efficiency of volatile solids at 60.8%, 18% higher than the single-stage process. The thermophilic and hyper-thermophilic hydrolysis reactors contributed 23.5% and 21.7% solubilization of chemical oxygen demand (COD), respectively. The hydrolysis efficiency achieved in the single process was 49.7%, which was lower than the hydrolysis in the two-stage processes. Approximately 60% of COD was distributed in the solid fraction in the first stage, and more than half of the particle COD continued to hydrolyze in the subsequent second stage. The mass balance of COD and volatile solids removal performance illustrated the advantages of the temperature-phased process. Comparatively, the three mesophilic reactors all had strong stability.

The The Effect of Velocity Gradient and Camp Number on Solids Removal using Bio-Coagulant from Corbula faba Hinds Shells

The TSS and TDS values of water are required to meet the standard. Like coagulation, the pretreatment process in water helps reduce solid content in water. The coagulant destabilizes water pollutants and helps flocs formation with the coagulation process. This paper studies the performance of chitosan bio-coagulant produced from Corbula faba Hinds shells. The velocity gradient and the Camp number of solids removal were also evaluated. The velocity and period of rapid mixing varied from 110 to 150 rpm, and the velocity gradient (G) was 181.2 to 288.5 s-1. The mixing period also ranged from 1 to 5 minutes. The highest TSS and TDS removal resulted in 140 rpm or 260.2 s-1 and 4 minutes of mixing. The residual TSS and TDS decreased with the increase of Camp Number until reaching a point and increased again afterward.

Combined organic coagulants and photocatalytic processes for winery wastewater treatment

Due to the consumers demand for quality wines, washing and disinfection operations are necessary in wine productions, leading to the generation of large volumes of winery wastewater (WW) with a high organic content which has the potential to cause irreversible environmental impacts. The aim and novelty of this work is the production of natural organic coagulants (NOCs) to be applied in coagulation-flocculation-decantation (CFD) process. To complement this treatment process, it is also aimed the performed a photo-Fenton process, combining hydrogen peroxide (H2O2) and potassium persulfate (KPS). The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) showed that NOCs are carbon-based materials with adsorption capacity. Under the best operational conditions, NOCs achieved a turbidity removal between 86.2 and 98.9%, a total suspended solids (TSS) removal ranging between 85.0 and 94.9% and a dissolved organic carbon (DOC) removal ranging between 14.1 and 44.9%. To degrade the DOC present in the WW, different advanced oxidation processes (AOPs) were tested. Results showed that KPS-photo-Fenton, under the best operational conditions [Fe2+] = 2.5 mM, [KPS] = 1.0 mM, pH = 3.0, radiation UV-C mercury lamp (254 nm), agitation 350 rpm, temperature 298 K, reaction time 240 min achieved a DOC removal of 91.2 and 96.8%, with a H2O2 consumption of 156.9 and 199.0 mM, respectively for red and white WW. With application of combined CFD-KPS-photo-Fenton process, it was observed an increase of DOC removal with lower H2O2 consumptions. The energy consumption of the photosystem was evaluated by application of electric energy per mass (EEM). The application of KPS-photo-Fenton process achieved an EEM of 0.308 and 0.0309 kWh/g/L DOC, with a cost of 2.05 and 2.59 €/g/L DOC respectively for red and white WW. The combination of CFD-KPS-photo-Fenton decreased significantly the costs of treatment and the treated wastewater achieved the Portuguese legal values for wastewater discharge. This work shows that NOCs are a promising technology that can be an alternative to traditional metal salts, the combination of sulfate radicals with hydroxyl radicals can achieve high DOC removal and the combination of CFD with KPS-photo-Fenton process can decrease the operational costs.

Investigation of the inlet layout effect on the solid waste removal in an octagonal aquaculture tank

The optimization of the inlet layout in aquaculture systems is essential to ensure minimal solid waste discharge into the environment and improve fish production efficiency. In the present study, laboratory experiments were carried out to investigate the effects of the jetting position d/a (where d is the distance from the pipe axis to the tank side and a is the side length of the tank wall) and the jetting angle θ (the acute angle between the jetting direction and the nearest tank wall) on the solid waste removal efficiency in single-inlet and dual-inlet octagonal Recirculating Aquaculture System (RAS) tanks. To this end, three jetting positions (d/a) of 1/50, 1/8, and 1/4 and ten jetting angles (θ) of 0° to 80° were considered in the experiments. The Particle Image Velocimetry (PIV) technique was applied to measure the flow characteristics in the tank and analyze the solid waste removal under different working conditions. Residual mass of the solid waste, time of complete removal of solid waste, average velocity (vavg), and uniformity coefficient of velocity distribution (DU50) were analyzed to evaluate the solid waste removal efficiency. The obtained results indicate that adjustments of the inlet layout significantly affect the solid waste removal efficiency. It was found that a single-inlet tank with a d/a of 1/8 and θ in the range 10° to 40° has a good solid wastes removal performance, and the optimal efficiency occurs at a jetting angle of 30°. Moreover, the optimal solid waste removal efficiency in a dual-inlet tank can be achieved with a d/a ratio of 1/8 and a θ of 20°. The performed analyses reveal that from the aspect of solid waste removal efficiency, a tank with a d/a ratio of 1/8 outperforms a tank with a d/a ratio of 1/4 or 1/50. The results of this article offer novel insights in the layout of octagonal RAS tanks and provide a guideline to improve self-cleaning features of aquaculture tanks.

Potential of bioretention plants in treating urban runoff polluted with greywater under tropical climate.

Bioretention systems are among the most popular stormwater best management practices (BMPs) for urban runoff treatment. Studies on plant performance using bioretention systems have been conducted, especially in developed countries with a temperate climate, such as the USA and Australia. However, these results might not be applicable in developing countries with tropical climates due to the different rainfall regimes and the strength of runoff pollutants. Thus, this study focuses on the performance of tropical plants in treating urban runoff polluted with greywater using a bioretention system. Ten different tropical plant species were triplicated and planted in 30 mesocosms with two control mesocosms without vegetation. One-way ANOVA was used to analyze the performance of plants, which were then ranked based on their performance in removing pollutants using the total score obtained for each water quality test. Results showed that vetiver topped the table with 86.4% of total nitrogen (TN) removal, 93.5% of total phosphorus (TP) removal, 89.8% of biological oxygen demand (BOD) removal, 90% of total suspended solids (TSS) removal, and 92.5% of chemical oxygen demand (COD) removal followed by blue porterweed, Hibiscus, golden trumpet, and tall sedge which can be recommended to be employed in future bioretention studies.

Optimizing the desalination rate in a photoelectrocatalytic desalination cell (PEDC) by altering operational conditions

Abstract Desalination of seawater is a promising response to solving the lack of drinkable water. The separation of cations and anions is carried out by inserting a desalination cell in the middle of a novel design of photoelectrocatalytic desalination cell (PEDC). Different parameters were evaluated and optimized for increasing the capability of system to desalt hypersaline water. Ultraviolet illumination (UV) was used as the driving force, exciting coated titanium nanotubes on the anode electrode, producing electron/hole pairs that degraded organic matter. Methylene blue degradation by UV irradiation was performed, owing to a high salt concentration level, and desalinated to produce electrical current. Performance of PEDCs was investigated by salt content, pH, and ion-exchange resin. The results indicated that higher total dissolved solid (TDS) removal occurred in acidic environments in anode chamber whereas the maximum produced electrical current occurred in alkaline environments in the cathode chamber. Also, the higher amount of salt content in the middle chamber resulted in the high TDS removal until the amount of electrical conductivity in the middle chamber reached 190 mS/cm. The TDS removal rates with and without using resins in the middle of the desalination cell after 10 days were 70.69% and 51.37%, respectively.

Impact of skin contact time, oak and tannin addition on the chemical composition, color stability and sensory profile of Merlot wines made from flash détente treatment

The ability to create differentiated red wine styles is key to meeting the diverse preferences of wine consumers. This study investigated the composition and style of Merlot wines made from flash détente (FD) treated must fermented with different levels of grape solids and skin contact time, and the potential for pre-fermentation addition of enotannin (0.4 g/L) or oak chips (4 g/L) to stabilize color. Off-skins fermentations, with or without addition of enotannin, gave wines with enhanced red fruit and confectionery characters (P = 0.0001), whereas addition of oak chips gave wines with prominent dark fruit, vanilla, toasty and allspice characters (P = 0.0001). However, additives did not improve wine color stability. Macerative fermentation of FD must enhanced dark fruit, body and astringency ratings (P = 0.0001), with FD wines exhibiting less intense green, savory and dusty notes (P = 0.0001). The study demonstrated solids removal had a greater influence on wine composition and style than skin contact time.