PURWONO, Purwono and Hadiyanto, Hadiyanto and Budihardjo, Mochamad Arief (2025) INNOVATION OF SPIRAL ELECTROCOAGULATION TO OPTIMIZE MICROALGAE HARVESTING AND HHO GAS PRODUCTION. Doctoral thesis, UNIVERSITAS DIPONEGORO.

	Text COVER.pdf Download (217kB)
	Text COVER LENGKAP.pdf Restricted to Repository staff only Download (1MB)
	Text CHAPTER I.pdf Download (306kB)
	Text CHAPTER II.pdf Download (758kB)
	Text CHAPTER III.pdf Restricted to Repository staff only Download (331kB)
	Text CHAPTER IV.pdf Restricted to Repository staff only Download (276kB)
	Text CHAPTER V.pdf Restricted to Repository staff only Download (382kB)
	Text CHAPTER VI.pdf Restricted to Repository staff only Download (257kB)
	Text CHAPTER VII.pdf Restricted to Repository staff only Download (507kB)
	Text CHAPTER VIII.pdf Restricted to Repository staff only Download (569kB)
	Text CHAPTER IX.pdf Restricted to Repository staff only Download (733kB)
	Text CHAPTER X.pdf Restricted to Repository staff only Download (273kB)
	Text CHAPTER XI.pdf Restricted to Repository staff only Download (35kB)
	Text REFERENCES.pdf Download (274kB)

Abstract

Microalgae play an essential role in overcoming the problems of wastewater, energy crises, and food crises. The difficulty of developing reliable and costeffective microalgae harvesting and mass production techniques hinders efforts to use microalgae for multiple purposes. The main challenges of microalgae harvesting are small cell size, low biomass concentration, and electrostatic repulsion between cells. However, it may still be necessary to educate consumers about the advantages of using microalgae for biodiesel. The aims of this study include a literature review of HHO gas, an analysis of the microalgae harvesting process using spiral electrocoagulation (SEC), HHO gas production, waste water quality, and Generation Z consumers' knowledge, awareness, acceptance, and willingness to pay for microalgae fuels. The method involves Scopus-based bibliometric analysis, laboratory experiments, and questionnaires. We harvested Chlorella sp and Dunaliella salina using SEC. We used Response Surface Methodology (RSM) to optimize the process efficiency. This study successfully identified 32 relevant documents relating to HHO gas production through electrolysis. The electrolyte's properties, concentration, and electrode spacing all have an impact on increasing HHO gas production. After charging an electrocoagulation spiral (SEC) with 15 V for 20 minutes, it successfully harvested Chlorella sp. with a 97.34% success rate. The concentration of dissolved hydrogen gas is a maximum of 1214 ppb at 30 minutes. Dunaliella salina harvesting in <5 minutes generates a maximum dissolved hydrogen gas concentration of 820 ppb at 18 V for 3 minutes. Scaling up the reactor to 1500 mL produced a dissolved hydrogen gas concentration of 1753 ppb and a total HHO gas volume of 1978 mL after a 30-minute harvest duration at 20 volts. Applying a voltage of 20 V for 5 minutes results in a harvesting efficiency of 74.6% for D. salina at low concentrations. The power consumption needed to harvest D. salina at a low concentration is 0.426517 kWh/kg of biomass. We successfully reduced the concentration of total ammonia nitrogen (TAN) in wastewater to 98.8% when applying electrocoagulation for 5 minutes. On the other hand, the harvesting efficiency of D. salina reached 93.72%. According to the Central Composite Design (CCD) design, the minimum COD concentration is 3.36 mg/L. The SEC successfully reduced the nutrients (nitrate and phosphate) in the wastewater by 97% within one minute at 20 volts. Overall, the concentration of nutrients produced after the harvesting process varies greatly depending on the variation in the SEC reactor's voltage, time, and slope. After 30 minutes of electrolysis, scale-up reactors of up to 1500 mL were able to harvest a maximum of 84.74% D-salina. The response surface methodology (RSM) found that 25 V, 4.17 min, and an angle of 68.39 degrees for the reactor were the best conditions for harvesting D. Salina, which resulted in an 85.77% harvesting efficiency. Based on social aspects, respondents support the development of microalgae as a biofuel source, are knowledgeable of the benefits of beneficial microalgae, and are willing to pay more for environmentally friendly fuels. Respondents stated the importance of environmental considerations in purchasing decisions.
Keywords: microalgae harvesting, electrocoagulation, Dunaliella salina, HHO, respondent knowledge

Actions (login required)

View Item