Evaluation of flue gas desulfurization gypsum as a low-cost precipitant for phosphorus removal from anaerobic digestion effluent filtrate

Land application of anaerobic digestion(AD)effluent as a fertilizer is desirable for nutrient recycling,but often supplies excess phosphorus(P),which contributes to surface water eutrophication.Reducing the P content in AD effluent filtrate using calcium(Ca)treatment prior to land application is a potential strategy for improving effluent disposal and meeting the discharge standard.This study took flue gas desulphurization(FGD)gypsum,a by-product of coal-fired power plants,as a low-cost Ca source,and combined with traditional phosphorus removal agents to achieve high phosphorus removal efficiency with less chemical cost.As the results showed,FGD gypsum dosages of 20 mmol/L Ca(3.44 g/L)and 40 mmol/L Ca(6.89 g/L)removed up to 97.1%of soluble P(initially 102.8 mg/L)within 60-90 minutes.Combining FGD gypsum treatment with traditional chemical treatments using calcium hydroxide[Ca(OH)2]or ferric chloride(FeCl3)could achieve>99%P removal with reduced chemical costs.This study demonstrated that FGD gypsum is an efficient calcium-based precipitant for phosphorus removal,offering a cost-effective and sustainable approach to enhance wastewater treatment practices and meet discharge standards in wastewater management.

Biopesticide production using Bacillus thuringiensis kurstaki by valorization of starch industry wastewater and effluent from aerobic,anaerobic digestion

Introduction Unconventional alternatives such as aerobic and anaerobic effluent from starch industry contain essential nutrients for Btk active ingredient synthesis.Effluent from starch industry is rich in carbon and nitrogen and can replace expensive feedstock used during the fermentation process.Objectives The main objective of this study was to achieve a biopesticide formulation from starch industry wastewater(SIW)with high entomotoxicity(UI/ml)of larvae comparable to Foray 76B,which is a commercial biopesticide.Methods Bacillus thuringiensis var kurstaki HD1(Btk)strain was cultivated and sub-cultured to aerobic,anaerobic digested effluent and SIW.Pre-treatment was carried on these different substrates to enhance the residual carbon required for Btk growth and delta endotoxin synthesis.After 48 hours of fermentation,cells count and delta-endotoxin were determined.A biopesticide formulation containing fermented broth and adjuvants was fed to larvae to determine larvae mortality.Results Btk cell growth and sporulation profile in SIW media displayed a high total cell count and viable spores compared to btk growth in anaerobic or aerobic media after 48h fermentation.The maximum endotoxin concentration in the SIW medium was 435μg/mL,whereas,in anaerobic and aerobic effluent,the maximum concentrations were at 161μg/mL and 136μg/mL,respectively.When acidic treatment was performed at pH 2 for these substrates,entomotoxicity obtained from aerobic and anaerobic biopesticide formulations displayed significantly higher entomoxicity than the untreated ones.The entomotoxicity of SIW treated at pH 2 was equivalent to the standard Foray 76B which is 20,000 IU/μL.Conclusion Anaerobic and aerobic effluent did not contain enough total organic carbon to augment Btk growth and entomo-toxicity.Substrates pre-treated at pH 2 provided significant organic matter for Btk growth and resulted in larval mortality equivalent to the com ercial biopesticide Foray 76B.

Hybrid Donnan dialysiseelectrodialysis for efficient ammonia recovery from anaerobic digester effluent

Ammonia recovery from wastewater is crucial,yet technology of low carbon emission and high ammonia perm-selectivity against complex stream compositions is urgently needed.Herein,a membrane-based hybrid process of the Donnan dialysiseelectrodialysis process(DDeED)was proposed for sustainable and efficient ammonia recovery.In principle,DD removes the majority of ammonia in wastewater by exploring the concentration gradient of NH4 t and driven cation(Nat)across the cation exchange membrane,given industrial sodium salt as a driving chemical.An additional ED stage driven by solar energy realizes a further removal of ammonia,recovery of driven cation,and replenishment of OHtoward ammonia stripping.Our results demonstrated that the hybrid DDeED process achieved ammonia removal efficiency>95%,driving cation(Nat)recovery efficiency>87.1%for synthetic streams,and reduced the OH-loss by up to 78%compared to a standalone DD case.Ammonia fluxes of 98.2 gN m^(-2)d^(-1)with the real anaerobic digestion effluent were observed using only solar energy input at 3.8 kWh kgN^(-1).With verified mass transfer modeling,reasonably controlled operation,and beneficial recovery performance,the hybrid process can be a promising candidate for future nutrient recovery from wastewater in a rural,remote area.

Nutrients removal and biomass production from anaerobic digested effluent by microalgae: A review

This article summarizes the recent progress of nutrient removal from wastewater via microalgae.Removal of nitrogen and phosphorous compounds from wastewater are of great importance,while those compounds are suitable for growth of some microalgae species.Such a combination provides more opportunities for anaerobic digestion facilities,which are producing large amount of wastewater with high nitrogen and phosphorous contents.However,in order to optimize and maximize the performance and durability of the nutrient removal process,it is suggested that the basic principles about nitrogen and phosphorous migration should be investigated thoroughly,especially from the fundamentals of substance transfer mechanism between water environment and algal cells.

Biocrude oil production from Chlorella sp.cultivated in anaerobic digestate after UF membrane treatment

Algae cultivation in animal wastewater could recover nutrient resources,and harvest considerable amount of algae biomass for biofuel conversion.In this study,Chlorella sp.cultivated in ultrafiltration(UF)membrane treated anaerobic digestion effluent of chicken manure was converted into biocrude oil through hydrothermal liquefaction(HTL).The potential of biocrude production from grown Chlorella sp.was studied through changing the operational conditions of HTL,i.e.,holding temperature(HT,250℃-330℃),retention time(RT,0.5-1.5 h),and total solid(TS)(15 wt%-25 wt%)of the feedstock.The highest biocrude oil yield was 32.9%at 330℃,1.5 h and 20 wt%TS.The single factor experiments of HT also suggested that the biocrude oil yield decreased when the temperature was higher than 330℃.There were no significant differences of elemental contents in biocrude samples.The maximum higher heating values(HHV)of Chlorella sp.biocrude was 40.04 MJ/kg at HT of 330℃,RT of 1 h and TS of 15 wt%.This study suggests the great potential for energy recovery from Chlorella sp.cultivated in UF membrane treated anaerobic digestion effluent via HTL.