Removal of phosphorus from domestic wastewater using discontinuous aerobic anoxic reactor

The discharge of excessive amounts of phosphorus (P) from domestic wastewater treatment plant is of interest in this study because the abnormally high levels of P as one of the nutrient elements can lead to eutrophication for the receiving waters. Although many methods have been proposed for the removal of P matter from industrial and municipal wastewater, such as Phoredox, A2OTM and UCT-type, the use of alternating aerobic-anoxic (AAA) system must be verified. This study proposes the use of Discontinuous Aerobic-Anoxic Reactor (DAAR) to remove P from domestic wastewater at Taman Impian Emas, Skudai, Johor using the nitrification and denitrification type of activated sludge. The objectives of this study are: (1) to evaluate the efficiency of P removal from domestic wastewater by a single reactor under aerobic digestion (AD) condition, and (2) to assess the performance of AAA process of using the different cycles of nitrification-denitrification to remove P from domestic wastewater. The average efficiency of AD to remove P from domestic wastewater was 48%. The efficiencies of AAA system to remove P from domestic wastewater, on the other hand, were verified as follows: (1) at 6-h AD and 6-h anoxic time (AT), the efficiency was 0%, indicating that there was no removal of P during the AAA process, (2) at 5-h AD and 5-h AT, the average efficiency was 48%, (3) at 4-h AD and 4-h AT, the average efficiency was 82%, (4) at 3-h AD and 3-h AT, the average efficiency was 91%, and (5) at 2-h AD and 2-h AT, the average efficiency was 88%. Therefore, the AAA system has exhibited a better performance compared to AD. The results of the study also show that the best condition of AAA system had a period of 3-h AD and 3-h AT and reached 91% efficiency with an average treated effluent concentration of less than 1.0 mg P/L. High performance of the AAA process has been proven by using domestic wastewater from Taman Impian Emas, Skudai, Johor, giving new insights into environmental engineering practices

Removal of nitrogen pollutant from domestic wastewater

Water as a medium for waste transport would be easily contaminated by human activities. Many methods have been proposed to treat contaminated water to protect human health and biodiversity (Z. Daud et al., 2017). Due to upgrade the existing wastewater treatment plant facilities, the typically advanced technologies have been proposed to remove many types of pollutant, effectively (Tchobanoglous, Burton, & Stensel, 2004). The development of wastewater treatment plant needs to be considered leading economic indicators to have low operational and maintenance costs (Lewandowski, 2015; Shammas, Wang, & Wu, 2009). Aerobic digestion (AD) has been known since 1950 as biological wastewater treatment process to treat wastewater by removing the pollutants for instance colloids, organic compounds and suspended solids to avoid the excessive pollutants released into the receiving water (Shammas and Wang, 2007)

Phosphorus and eutrophication in water

Since early 1970, the presence of phosphorus (P) in domestic wastewater has attracted attention due to the awareness of its adverse impacts on the environment, specifically in receiving water such as a river. In the wastewater treatment system, P is a crucial nutrient for bacteria required to degrade and biologically stabilise the organic wastes (Hussain et al., 2001). P is a key nutrient that stimulates the growth of algae and other biological organisms (Mainstone and Parr, 2002). P appears exclusively as orthophosphate, condensed phosphates (polyphosphates), and organically bound phosphate. Condensed phosphates are utilised in cleaning products, and organic phosphates are elements of the body and food waste (Howard, 1985). According to Tjandraatmadja et al. (2010), household products can be a significant contributor to the P load in domestic wastewater. The release of high quantities of P from domestic wastewater treatment plants is of concern, as it is one of the key nutrients that have the potential to contribute to eutrophication in surface water, which can result in excessive growth of algae (Daniel et al., 1994)

The phytoremediation using water hyacinth and water lettuce : correlation between sugar content, biomass growth rate, and nutrients

Degradation of water quality due to the presence of pollutants in water is an emerging issue in many countries, including Malaysia. Phytoremediation is one of the environmentally friendly, cost-effective conventional technologies that are still used in modern times. However, the selection of plant species is the most important aspect for the application of phytoremediation in wastewater treatment. Nevertheless, there are species of floating aquatic macrophytes that are capable of coping with various pollutants present in wastewater. Among the various floating aquatic macrophyte species, water hyacinth (WH) and water lettuce (WL) have been described as effective phytoremediators in reducing water pollution through bioaccumulation in their body tissues. Hence, WH and WL were chosen in this study as it is easily found, propagated, and cultivated. This paper aims to determine the biosorption capacity of these species in eliminating various pollutants present in wastewater as well as to define the optimum harvesting time for each species. Although these floating aquatic macrophytes are considered the most problematic plants due to their uncontrollable growth in water bodies worldwide, their ability to remove pollutants from wastewater has created a sustainable approach for their use in phytoremediation. In this sense, the use of phytoremediation by implementing the invasive floating aquatic macrophytes can certainly support the sustainable management of wastewater treatment in the future. Based on the results, it was found that WH efficiently removed higher PO4 3-, NO3 - and NO2 - concentrations compared to WL from the wastewater. Both WH and WL showed the same trend of correlation between the growth rate and sugar content, where the sugar content increased when the plants reached the highest growth rate. The maximum nutrient uptake occurred in 14-17 days, proving that nutrient availability is critical for plant growth. This study concludes that the sugar content of WH and WL are increased with the biomass growth rate, and both plants species are competent in eradicating the nutrient pollution in wastewater. On top of that, this study infers that the maximum harvesting period for WH biomass is on day 18, while WL biomass is on day 21; based on the highest sugar content and biomass weight of each species

Mass transfer kinetics and mechanisms of phosphate adsorbed on waste mussel shell

An excessive amount of phosphate (PO4 3−) released from domestic wastewater treatment plant efuent (DWTPE) may trigger eutrophication of water causing a degradation of healthy aquatic eco�system. Even though the PO4 3− ions can be removed from aqueous solution with an adsorption technique using the low-cost adsorbent, the adsorption kinet�ics of PO4 3− removal must be understood. The bed depth service time (BDST), Thomas and modifed mass transfer factor (MMTF) models were used to investigate the adsorption kinetics of PO4 3− removed from DWTPE onto the waste mussel shell (WMS) applied to hybrid plug fow column reactor (HPFCR). Dynamic adsorption capacity of WMS described by the new modifed BDST model is shown to increase with increasing of the plug fow column (PFC) bed. The analysis of mass transfer behavior described using the Thomas model is able to predict the per�formance of HPFCR at certain depths of the PFC bed. The use of the MMTF models could be useful to describe the real diference between the behav�iors of flm mass transfer and porous difusion. The resistance of PO4 3− mass transfer depending on porous difusion has been verifed to provide a contri�bution in the development of advanced WMS adsor�bent for enhancing the HPFCR performance in the future

A two-stage batch system for phosphate removal from wastewater by iron-coated waste mussel shell to assess the optimum adsorbent dosage

High amounts of phosphate discharged in receiving water can lead to eutrophication. Once a water body is enriched with phosphate, it can prompt the growth of plants and cause algal blooms. The water body may also lose its important functions and cause adverse effects on the environment and human health. In this study, removal of phosphate from domestic wastewater treatment plant effluent was elucidated using iron-coated waste mussel shell. The phosphate adsorption by iron-coated waste mussel shell was examined with respect to initial phosphateconcentration (7 mg L–1), solution volume (0.2 L), adsorbent dosage (4–20 g), and contact time (1–5 day). The chemical composition of iron-coated waste mussel shell was analyzed using energy dispersive X-ray fluorescence spectrometer. The measurement of the specific surface area of iron-coated waste mussel shell was performed by multiple-point method according to the Brunauer, Emmett, and Teller theory. Several kinetic models (i.e., pseudo-first order and pseudo-second order) and isotherm models (i.e., Freundlich and Langmuir) were used to describe the adsorption behavior. The optimum removal efficiency of phosphate can reach at 95.7% after 120 h with the amount of iron-coated waste mussel shell used to run the experiment was 20 g and the treated effluent phosphate concentration of 0.3 mg L–1, was verified. Experimental data can be well described by pseudo-second order kinetic model (R2 > 0.99) and Freundlich isotherm model (R2 = 0.93), suggesting that chemisorption and multilayer adsorption occurred. Furthermore, a two-stage batch system was proposed to assess the optimum adsorbent dosage for phosphate removal. The two-stage system has contributed to reduce iron-coated waste mussel shell dosage by 56.94%, as compared to one-stage and thus reduced the operating cost of iron-coated waste mussel shell

Removal of phosphate from synthetic wastewater by using marsh clam (polymesoda expansa) shell as an adsorbent

Phosphate pollution is becoming a serious problem worldwide. It leads to increased algae growth, resulting in eutrophication, which affects the water bodies’ quality, the lives of aquatic organisms, and the daily routines of humankind. Previous research has proven effective chemical precipitation for phosphate removal, but the cost is high and may generate waste material. Thus, this study proposed the marsh clam (Polymesoda expansa) shell as an absorbent due to its abundant availability, low cost, and high absorption capacity of phosphorus. This study was conducted to investigate the removal efficiency of phosphate using raw marsh clamshells. In this study, the concentration of aqueous solution using KH2PO4 was fixed to 10 mg/L of PO4 3− as the initial concentration. The 2 g of mass absorbent (0.075mm, 0.15mm, 0.30 mm, 0.60 mm, 1.18 mm, 2.36 mm) mixed with 100mL of KH2PO4 solution in the conical flask in a certain time interval. The orbital shaker was used for mixing the KH2PO4 solution with the adsorbent. Moreover, HACH DR 6000 Spectrophotometer is then used to determine phosphate concentration for initial and final results. The results were verified using kinetic and isotherm models, where kinetic models used Pseudo First Order (PFO) and Pseudo Second Order (PSO). The isotherm model used the Freundlich and Langmuir models. The optimum performance of the batch experiment showed by the PSO model had the highest correlation coefficient (R2 = 0.9965) and the lowest Fe value of 0.086. This study showed that marsh clamshells could remove PO4 3− effectively for 1.18–2.36 mm size with the highest removal efficiency of 73%. The removal of phosphate from domestic wastewater can be an alternative wastewater treatment in tertiary treatment in the field of the wastewater treatment plant

Interpretation of isotherm models for adsorption of ammonium onto granular activated carbon

High amounts of ammonium (NH4+) discharged in receiving water can lead to eutrophication. The adsorption of NH4+ from synthetic solution onto granular activated carbon (GAC) was scrutinized with respect to initial solute concentration (10 mg L-1 ), solution volume (0.2 L), adsorbent dosage (4 – 20 g), and contact time. Experimental data can be well described by the pseudo-second-order kinetic model (R2 > 0.994) and Freundlich isotherm model (R2 = 0.936), suggesting that chemisorption and multilayer adsorption occurred. Furthermore, this study explored the feasibility of using the Freundlich isotherm model to estimate the removal efficiency or required amount of adsorbent. The result findings indicated that GAC has a good potential to adsorb NH4+ from water and thus giving new insights into environmental engineering practices

Phosphate removal from wastewater in batch system using waste mussel shell

High input of phosphate (PO43–) in rivers can lead to eutrophication, which jeopardizes aquatic life and human health. In this study, PO43– was removed from synthetic solution and domestic wastewater treatment plant effluent (DWTPE) by waste mussel shell (WMS). The PO4 3– adsorption by WMS was examined for the initial PO4 3– concentration (7 mg L-1), solution volume (0.2 L), adsorbent dosage (4, 8, 12, 16, and 20 g), and contact time (1-6 d). The batch experiment's optimum performance could reach approximately 75.1% for the removal of PO4 3– from synthetic solution and approximately 66.2% for the removal of PO43– from DWTPE after a contact time of 5 d. This work suggests that the WMS can remove PO43 from both synthetic solution and DWTPE. Future works are necessary to increase WMS's capacity to adsorb PO4 3– from waters, either by physical or chemical modification

Mass transfer kinetics of phosphate removal from sewage treatment plant effluent by waste mussel shell

Excessive amount of phosphate (PO43-) released from sewage treatment plant effluent (STPE) may trigger eutrophication of water causing degradation of aquatic ecosystem and human health. Even though the presence of PO43- ions in aqueous solution can be removed using adsorption techniques, detailed description of adsorption kinetics is still not fully understood. In this study, the isotherm and kinetic adsorption of PO43- from aqueous solution onto porous material were conducted in batch experiments. A typical design of the hybrid plug flow column reactor (HPFCR) was used to remove PO43- from STPE. The kinetic models (i.e., pseudo-first-order (PFO) and pseudo-second-order (PSO)) and the isotherm models (i.e., Freundlich and Langmuir) were used to determine the adsorption kinetics and isotherms of PO43- from STPE onto waste mussel shell (WMS) and iron-coated waste mussel shell (ICWMS) adsorbents. The empirical models of bed depth service time (BDST), Thomas, and modified mass transfer factor (MMTF) were used to describe the adsorption kinetic processes of PO43- of WMS and ICWMS applied in the HPFCR. The experimental data for the adsorption of PO43- onto both WMS and ICWMS adsorbents fitted very well with the PSO kinetic model and Freundlich isotherm model, respectively. The dynamic adsorption capacity of WMS and ICWMS described by the BDST model has shown to increase with increase in the plug flow column (PFC) depth. The hydrodynamic behavior of PO43- global mass transfer can be described using the Thomas models for predicting the PFC performance. Employing the MMTF models enabled differentiation between the behavior of film mass transfer and porous diffusion. The resistance of PO43- mass transfer is dependent on porous diffusion and this contributes to the development of advanced WMS and ICWMS adsorbents in enhancing the performance of the HPFCR system in the future